Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

Facile synthesis of graphene wool doped with oleylamine-capped silver nanoparticles (GW-αAgNPs) for water treatment applications

Facile synthesis of graphene wool doped with oleylamine-capped silver nanoparticles (GW-αAgNPs)... The facile synthesis of graphene wool doped with oleylamine-capped silver nanoparticles (GW-αAgNP) was achieved in this study. The effect of concentration, pH, temperature and natural organic matter (NOM) on the adsorption of a human carcinogen (benzo(a)pyrene, BaP) was evaluated using the doped graphene wool adsorbent. Furthermore, the antibacterial potential of GW-αAgNP against selected drug-resistant Gram-negative and Gram-positive bacteria strains was evaluated. Isotherm data revealed that adsorption of BaP by GW-αAgNP was best described by a multilayer adsorption mechanism predicted by Freundlich model with least ERRSQ < 0.79. The doping of graphene wool with hydrophobic AgNPs coated with functional moieties significantly increased the maximum adsorption capacity of GW-αAgNP over GW based on the q and q predicted by Langmuir and Sips models. π-π interactions contributed to sorbent-sorbate interaction, due to the max m presence of delocalized electrons. GW-αAgNP-BaP interaction is a spontaneous exothermic process (negative ΔH and ΔG) , with better removal efficiency in the absence of natural organic matter (NOM). While GW is more feasible with higher maximum adsorption capacity (q ) at elevated temperatures, GW-αAgNP adsorption capacity and efficiency is best at ambi- ent temperature, in the absence of natural organic matter (NOM), and preferable in terms of energy demands and process economics. GW-αAgNP significantly inhibited the growth of Gram-negative Pseudomonas aeruginosa and Gram-positive Bacillus subtilis strains, at 1000 mg/L dosage in preliminary tests, which provides the rationale for future evaluation of this hybrid material as a smart solution to chemical and microbiological water pollution. Keywords Adsorption · Antimicrobial property · Graphene wool composite · Silver nanoparticles · Water treatment Introduction environment and poses health risk due to its recalcitrance to biodegradation (Yerushalmi et al. 2006). The maximum Benzo(a)pyrene (BaP) is regarded as one of the most haz- acceptable concentration (MAC) of PAHs in surface water is ardous environmental pollutants exhibiting both genotoxic 0.01 µg/L; however, several reports suggest that BaP levels and carcinogenic toxicity in humans according to the Inter- detected in South Africa are higher than the MAC value, national Agency for Research on Cancer (IARC) (IARC thus posing a potential health risk (Adeniji et al. 2019). 2010; Hardonnière et al. 2016). BaP belongs to the group Furthermore, the adaptive resistance of several bacteria of ubiquitous emerging chemical pollutants (ECPs) known to antibiotics, such as chloramphenicol, penicillin, etc., has as polycyclic aromatic hydrocarbons (PAHs) (Adeola & led to the interesting discovery that silver nanoparticles can Forbes 2020; Munyeza et al. 2020). BaP is persistent in the inhibit microbial growth and may be lethal against drug- resistant bacteria (Anthony et  al. 2014; McBirney et  al. 2016; Huang et al. 2017). Advances in research into a hybrid * Patricia B. C. Forbes approach to environmental protection and remediation have patricia.forbes@up.ac.za brought about the need for the development of “smart” materials/composites with multifunctional capabilities for Department of Chemistry, Faculty of Natural and Agricultural Sciences, University of Pretoria, Lynnwood improved efficiency and process economics (Bezza and Road, Hatfield, Pretoria 0002, South Africa Chirwa 2016; Miren et al. 2018; Adeola & Forbes 2021b). Water Utilisation and Environmental Engineering Division, Several materials with antimicrobial properties have been Department of Chemical Engineering, University of Pretoria, developed for the removal of pollutants in aqueous matrices, Lynnwood Road, Hatfield, Pretoria 0002, South Africa Vol.:(0123456789) 1 3 172 Page 2 of 15 Applied Water Science (2021) 11:172 examples of such materials are polyanilineTi(IV)arseno- calcium chloride (CaCl ) were purchased from Associated phosphate (Bushra et al. 2014), iron and manganese coated Chemical Enterprises (ACE, Johannesburg, South Africa). silica gel (Ahmad et al. 2015), chitosan doped with silver 9–30  μm coarse quartz wool (Arcos Organics, New Jer- nanoparticles (Ishihara et al. 2015), nano-silver-supported sey, USA), argon, and hydrogen (99.999%, Afrox, South activated carbon (Eltugral et al. 2016), graphene foam/TiO Africa) were purchased for GW synthesis. Sterile syringe nanosheet hybrids (Wang et al. 2017), iron nanoparticles filters (33 mm diameter) with a 0.22 µm pore size contain- (Da’na et al. 2018), silk fiber doped with tannic acid (Zhang ing a hydrophilic polyethersulfone (PES) membrane were et al. 2019), antimicrobial polymer (Li et al. 2020) chitosan/ purchased from Merck (Darmstadt, Germany). The anti- nitrogen-doped graphene quantum dots (Amari et al. 2021), bacterial tests were carried out using model Gram-negative etc. The design of composites has reportedly enhanced phys- Pseudomonas aeruginosa CB1 and Gram-positive Bacil- icochemical properties of adsorbents such as specific sur - lus subtilis CN2 bacterial strains that had been previously face area, stability, conductivity, tensile strength, chemical isolated and deposited in the GenBank database under the robustness, charge mobility, flexibility, thin-film thickness, accession numbers KP793922 and KP7939228, respectively and provided a basis for the growing interest in the utiliza- (Bezza and Chirwa 2016). All the solutions were prepared tion of composites for water treatment applications (Adeola with de-ionized water (DI, 9.2 µS/cm ) obtained from a & Forbes 2021b). Milli-Q water purification system (Millipore, Bedford, MA, A comprehensive risk-based assessment of graphene- USA). based composites is currently unavailable; however, it is assumed that the composites may not pose a significant Facile synthesis of GW‑αAgNPs health risk based on their composition, but their lightweight nature may pose inhalation risks (Schinwald et al. 2012). Graphene wool was synthesized using the chemical vapor Thus, the physical structure of the graphene-based material deposition method on a quartz wool substrate whereby an and the fabrication method is critical. With respect to gra- optimized stream of argon, hydrogen, and methane gas was phene wool doped with oleylamine-capped silver nanoparti- temperature ramped to 1200  °C as previously described cles (GW-αAgNPs), the quartz wool substrate acts as a solid (Adeola & Forbes 2019, 2020; Schoonraad et  al. 2020). support, assisting with immobilization of the graphene and Lipopeptide-coated silver nanoparticles were synthesized in silver nanoparticles. Furthermore, unlike most composites phenyl ether with oleylamine and oleic acid as both reducing generated in the form of flakes and powder, GW-αAgNPs agents and capping agents (Liu et al. 2011; Sha et al. 2011; presents a wool-like form that may be more suitable as a Çınar et al. 2011). packing material for filters and other water polishing tools. The composite was prepared as follows: Briefly, GW The overall aim of this study was to synthesize a compos- (200 mg) and DI water (100 mL) were added into a sealed ite of graphene wool and silver nanoparticles (GW-αAgNPs) bottle (250 mL) and stirred gently for 1 h using a magnetic with antibacterial activity, for the removal of a human car- stirrer, before the addition of the dopant mixture. Ag nano- cinogen, namely benzo(a)pyrene, from polluted water. The particles (300 mg) dispersed in diphenyl ether (100 mL) influence of process variables such as pH, temperature, and were added into the GW solution and stirred for 12 h at room initial concentration of BaP on the sorption mechanism was temperature under argon, to ensure that AgNPs coordinated established for optimum efficiency of the composite. Fur - with graphene wool at the water/diphenyl ether interface. thermore, the antibacterial activity of the composite was The GW–αAgNP composite was rinsed with acetone and tested and is discussed briefly for potential dual application centrifuged at 6000 rpm for 10 min, three times consecu- toward water treatment. tively. The obtained GW–αAgNP composites were then washed with hexane to remove residual oleylamine. The final GW–αAgNP composite was freeze-dried for 48 h. The facile Experimental methods synthesis is illustrated in Scheme 1. Chemicals Characterization of the synthesized adsorbent Neat standard (98% purity) of benzo(a)pyrene (BaP) was The morphology of GW and GW-αAgNPs was examined purchased from Supelco (USA). Sodium azide (NaN ), silver by a combination of techniques including scanning elec- nitrate (AgNO , 99.9%), oleic acid (99%), oleylamine (99%), tron microscopy (SEM), with images obtained from a Zeiss phenyl ether (99%), and Tryptic Soybean Broth (TSB) were Ultra-Plus 55 field emission scanning electron microscope purchased from Sigma-Aldrich (Germany). Nitric acid (FE-SEM), operated at 2.0 kV (Zeiss, Germany). High-res- (HNO ), hydrochloric acid (HCl), sodium chloride (NaCl), olution transmission electron microscopy (TEM) images of sodium hydroxide (NaOH), ethanol (EtOH), hexane, and capped-AgNPs and GW-αAgNPs were taken using a JEOL 1 3 Applied Water Science (2021) 11:172 Page 3 of 15 172 Scheme 1 Illustration of the synthetic route to graphene wool-silver nanoparticles composite JEM 2100F (JOEL Ltd, Tokyo, Japan) operated at 200 kV with initial concentrations of the BaP solutions ranging from and equipped with an energy dispersive X-ray spectrom- 100 µg/L to 500 µg/L. The BaP desorption isotherm was eter (EDS) (OXFORD Link-ISIS-300 Zeiss, Germany). The examined by the addition of 5 mL fresh electrolyte with specific surface area (SSA) of GW was determined using equilibration for 24 h, after decanting the adsorption super- the modified Sears’ method (Sears 1956; Adeola & Forbes natant as previously described (Wang et al. 2008; Adeola 2019). FTIR spectra of GW, capped AgNPs and GW- & Forbes 2021a). Adsorption isotherms of BaP were also αAgNPs were obtained using a Bruker Alpha-T spectrometer performed at varying temperatures of 25, 35, and 45 °C (Bruker Optik GmbH, Ettlingen, Germany). Elemental anal- using a thermostated shaking water bath (Wisebath, Celsius ysis of natural organic matter (NOM) was examined using Scientific, South Africa) to determine adsorption thermody - inductively coupled plasma-optical emission spectrometry namics. The role of solution pH was evaluated by pH adjust- (ICP-OES, Spectro Arcos model, Thermo Fisher Scientific, ment with 0.1 M HCl (Merck, South Africa) or NaOH (ACE, South Africa). The conductivity of the background electro- South Africa) over the pH range from 2 to 12, to elucidate lyte was confirmed using an Orion Star A112 conductivity the pH effect on the removal of BaP from aqueous solution. benchtop meter (Thermo Scientific, South Africa), and pH was monitored using a 780-pH meter (Metrohm Herisau, Quantification Switzerland). After equilibration, centrifugation of the vials was per- Sorption isotherm experiments formed at 6000 rpm for 10 min to recover a clear superna- tant. BaP concentrations were analyzed in triplicate (n = 3) Batch adsorption experiments of BaP onto GW and by fluorescence spectroscopy (Horiba Jobin Yvon Fluoro- GW-αAgNPs were carried out in 40 mL PTFE screw cap max-4 spectrofluorometer). For all fluorescence measure- amber vials (Stargate Scientific, South Africa) at 25 ± 1 °C ments, the excitation and quantification emission wave- in a thermostated shaking water bath (Wisebath, Celsius lengths were at 330 and 464 nm, while the excitation and Scientific, South Africa). Background electrolyte (pH = 7.0) emission slit widths were set at 5 nm. The regression coef- contained 0.01  mol/L CaCl (ACE, South Africa) in DI ficient (R ) of the calibration curve was obtained from work- water with 200 mg/L of sodium azide (Sigma-Aldrich, Ger- ing solutions in the range of 100 µg/L to 500 µg/L of BaP many) as a biocide. The isotherm experiment was conducted and blanks were included for both calibration and sorption 1 3 172 Page 4 of 15 Applied Water Science (2021) 11:172 experiments. The equilibrium concentration (C , µg/L) was of 12.67 ± 3.9 nm were estimated via particle size analy- deduced from the calibration equation. The amount of solute sis using the ImageJ software (Fig. 1b and d). Qualitative adsorbed (q , µg/g) was extrapolated using a mass-balance analysis of GW-αAgNP using EDS confirmed the presence equation (Eq. 1) and removal ec ffi iency was estimated using and relative abundance of silver and carbon (Fig. 1c). FTIR Eq. 2: (Fig. 1e and f) revealed two prominent peaks associated with the sp hybridized C=C backbone of graphene and a broad (C − C )V 0 e 0 peak of Si–O-C of functionalized quartz wool (SiO ) coated q = (1) 2 S −1 with graphene at 775 and 1059  cm , respectively (Adeola −1 & Forbes 2020). Bands at 2921, 2856, 1631, 1450  cm where C (µg/L) is the initial concentration, C (µg/L) is the o e regions arising from C–H, C=O, C–N stretching vibrations equilibrium solute concentration, V is the initial volume (L) were observed in GW-αAgNP, respectively (Fig. 1e). Fig- and S is the mass (g) of the adsorbent. ure 1f revealed that several functional groups enhanced the (C − C ) stability of AgNPs and facilitated coordination with GW 0 e Removal efficiency(%) = × 100 (2) (Jyoti et al. 2016). The bands at 3325, 2921, 2856, 1743, −1 1631, 1450, 1377, 1240, 1043 and 460  cm correspond to N–H, C–H, C–C, C=O, C–N, C=N, and Ag–O stretching, Antibacterial test of GW‑ αAgNPs respectively, indicating the presence of oleylamine/oleic acid as the capping agent of silver nanoparticles (Mojahed et al. Sterilization of all glassware and media was carried out in an 2011; Prakash et al. 2013; Tran & Jeong 2015). autoclave at 121 °C for 15 min. A facile test was conducted of bacteria inhibition of GW-αAgNP against model Gram- Sorption isotherm experiments negative and Gram-positive bacteria strains (Pseudomonas aeruginosa CB1 and Bacillus subtilis CN2) previously iso- Adsorption isotherm models are used to investigate the lated in our laboratory (Bezza et al., 2020). The inocula of P. nature of sorbent-sorbate interactions of adsorption (Wang aeruginosa and B. subtilis were cultured overnight in Tryptic et  al. 2018; Zhang et al. 2019; Adeola & Forbes 2021a). Soybean Broth (TSB) under aerobic conditions at 37 °C. Linear regression and nonlinear isotherm models such as The inhibitory concentration of the composite against vis- Linear (Eq. 3), Freundlich (Eq. 4), Langmuir (Eq. 5), and ible growth of P. aeruginosa and B. subtilis after 24 h of Sips model (Eq. 6) were used to fit adsorption experimental incubation at 37 °C was investigated. Concentrations ranging data. The Error Sum of Squares (ERRSQ) (Eq. 7) was used from 0–1000 mg/L of GW-αAgNP were prepared in steri- to test all models used in this study. lized conical flasks containing 100 mL TSB. Thereafter each flask was inoculated with 10 µL of the cultured inoculum. q = K C (3) e d e Optical density measurements were taken after the incuba- tion period. Experiments were conducted in duplicate and q = K C (4) e F controls containing nutrient broth inoculated with inoculum without the inclusion of GW-αAgNPs. Bacteria concentra- q K C tion was estimated in relation to absorbance/optical den- max L e q = (5) sity at 600 nm (OD ) using a UV/Vis spectrophotometer 1 + K C L e (Shimadzu UV-1800, Labotec, South Africa) and corrected by subtracting the background absorbance of the control ms q K C m s (Anthony et al. 2014; Bezza et al. 2020). q = (6) e ms 1 + K .C Results and discussion (q − q ) (7) e,cal e, exp i=1 Adsorbent characterization where K (mg/g) (L/mg) ) and N (dimensionless) is the Freundlich constant and intensity parameter, an indicator The morphology of the synthesized composite was exam- of site energy heterogeneity; q (mg/g) and K (L/mg) max L ined using SEM and TEM (Fig. 1a and b). The high-resolu- are the Langmuir maximum adsorption capacity and Lang- tion images revealed a heterogeneous surface structure with muir constant associated with solute–surface interaction extensive coverage of GW with AgNPs. The oleylamine- energy, respectively; K (L/mg) and q (mg/g) are Sips s max capped AgNPs were analyzed with TEM prior to conjuga- isotherm model constants and maximum adsorption capac- tion with GW, and spherical particles with a mean diameter ity and ms is Sips isotherm exponent; q is the solid-phase 1 3 Applied Water Science (2021) 11:172 Page 5 of 15 172 Fig. 1 Characterization of GW-αAgNP composite, a SEM image of abundance of constituent element obtained from EDS site mapping), GW-αAgNP (2 µm scale) (inset: TEM image of GW (200 nm scale)), d Particle size distribution of capped AgNPs with estimated diame- b TEM image of oleylamine-capped AgNPs prior to doping experi- ter, e and f FTIR spectra of GW, GW-αAgNP and oleylamine-capped ment (50 nm scale), c EDS spectrum of GW-αAgNP (inset: Relative AgNP concentration (mg/g), C is the liquid phase equilibrium con- irreversibility of the sorption process was calculated for centration (mg/L), and K (L/g) is the sorption distribution doped graphene wool and pristine graphene wool (Table 1). coefficient (Ololade et al. 2018; Adeola & Forbes 2019). Isotherm data for GW-αAgNP adsorption of BaP was best The isotherm regression parameters for Freundlich, Lang- described by a multilayer adsorption mechanism predicted muir, Linear, and Sips model are presented in Table 1 and by the Freundlich model with least ERRSQ < 0.79, while Fig. 2. The hysteresis index (H) which is a measure of the BaP adsorption onto GW was best fitted to the Sips model Table 1 Sorption–desorption Sorption models Adsorption parameters Desorption parameters parameters for adsorption of BaP onto GW-αAgNP and GW GW-αAgNP GW GW-αAgNP GW (desorption hysteresis index K 1.12e3 0.60e2 K 0.55e2 0.21e2 (H) derived from Freundlich f (ads) f (des) isotherm model) Freundlich N 3.13 0.1 N 0.1 0.01 (ads) (des) SSE 0.78 2.50 H-index 31.3 10.0 Langmuir q (µg/g) 13.67e3 0.59e2 max K (L/µg) 2.01e-4 6.67e4 SSE 2.03 1.88 Linear K 2.75 0.93 SSE 1.58 2.45 Sips K 3.36 2.38 q (µg/g) 97.62 59.76 m 9.68 6.05 SSE 2.03 1.87 H: Sorption–desorption hysteresis index, H = N /N ads des 1 3 172 Page 6 of 15 Applied Water Science (2021) 11:172 Fig. 2 Adsorption isotherm model plots for the interaction between sorbate and sorbents a GW and BaP b doped GW-αAgNP and BaP. (Experi- mental conditions: C = 100–500 µg/L; dosage = 5 mg per 5 mL, mixing rate = 200 rpm, T = 25 ± 1 °C, contact time: 24 h) (Langmuir–Freundlich hybrid) with ERRSQ < 1.88, respec- sorbed BaP was three-fold higher in GW-αAgNP than pris- tively (Table 1). These findings are consistent with previ- tine GW, further confirming higher binding strength with ous results obtained from the adsorption of phenanthrene BaP. Pore deformation and alteration of the surface struc- and pyrene onto pristine graphene wool (Adeola & Forbes ture of sorbents via build-up in unrelaxed pore volume also 2019). The doping of graphene wool with hydrophobic cause hysteretic behavior in sorption processes (Nguyen AgNPs coated with organic functional moieties significantly et  al. 2004; Cornelissen et al. 2005). Therefore, the high increased the maximum adsorption capacity of GW-αAgNP hysteretic behavior of GW-αAgNP, which exemplifies better over GW based on the q & q predicted by Langmuir and retention of BaP against recontamination of treated water, max m Sips models, respectively (Table 1). BaP is a hydrophobic maybe due to entrapment of solutes by the collapse of the PAH with a high octanol–water partition coefficient logK GW- αAgNP composite structure due to the adsorption pro- ow of 6.13 (Adeola & Forbes 2020), and several reports suggest cess conditions and agitation. a strong affinity between PAHs and hydrophobic surfaces of adsorbents (Khan et al. 2007; Lamichhane et al. 2016; Comparison of adsorbents reported for benzo(a)pyrene Yakout & Daifullah 2013; Yuan et al. 2018). π-π interac- removal tions between the graphene wool composite and the aro- matic structure of BaP, due to the presence of delocalized Table 2 reveals that graphene wool (GW) and doped gra- electrons, also contributes to the adsorption process (Zhao phene wool (GW-αAgNP) competes favorably with other et al. 2011; Zhang et al. 2013; Yang et al. 2015; Adeola & adsorbents reported in the literature for the removal of Forbes 2019). benzo(a)pyrene from aqueous solutions, with efficiency Furthermore, oleylamine and oleic acid used as capping ˃94%. The maximum adsorption capacity deduced from agents as well as the linker between GW and AgNP are large the Langmuir isotherm model (q ) for GW is lower than max hydrophobic organic molecules that may have improved the some of the adsorbents, however, the adsorption capacity of surface hydrophobicity of the composite. Thus, this may in GW-αAgNPs is higher than activated carbon (AC), biochar turn enhance partitioning (mass transfer) of hydrophobic and granular activated carbon (GAC) for BaP adsorption BaP onto the surface of the composite, leading to enhanced based on available literature. The higher adsorption capacity adsorption capacity (K and q ). The doping of graphene of GW-αAgNP may be due to surface modification associ- d max with oleylamine-capped AgNPs accounts for the compara- ated with the doping experiment; creation of binding sites/ tively high surface and adsorption heterogeneity (N & m ) pores and enhanced hydrophobic sorbate-sorbent interac- index (Table  1). It is evident that adsorption–desorption tions. Oleylamine and oleic acid used as capping agents as interactions between sorbate and sorbents displayed a sig- well as the linker between GW and AgNP are large hydro- nificant degree of hysteresis, as calculated H-index values for phobic organic molecules that may have improved the sur- both sorbates were greater than 1 (N > > > N ) (Table 1) face hydrophobicity of the composite. ads des (Ololade et al. 2018; Adeola & Forbes 2021a). However, Several factors influence the choice of adsorbent for water irreversible entrapment and/or slow rate of desorption of treatment applications, these factors include efficiency, 1 3 Applied Water Science (2021) 11:172 Page 7 of 15 172 Table 2 Comparison of different materials used for removal of benzo(a)pyrene from aqueous solutions Adsorbent Dosage (g/L) Removal effi- Adsorption Reference ciency (%) capacity (mg/g) Wood ash 10.0 > 99 - Pérez-Gregorio et al. (2010) Activated carbon derived from coconut shells 0.5 88 - Amstaetter et al. (2012) Iron oxide nanoparticles (IONPs) 0.13 99 0.029 Hassan et al. (2018) Granular activated carbon (GAC) 50.0 - 2.176 Minkina et al. (2021) Biochar 50.0 - 5.881 Minkina et al. (2021) Activated carbon derived from plastic waste 0.8 85 6.494 IIyas et al. (2021) Graphene wool (GW) 1.0 94.8 0.590 This study GW-αAgNPs 1.0 98.7 13.670 This study non-toxicity, availability of material, flexibility, reusability, etc. (Adeola et al. 2021). However, the wool-like form and porosity of GW-αAgNP, in addition to the potential antibac- terial activity (discussed in Sect. 3.6), are advantages to the use of GW-αAgNP as a packing material for water treatment applications. Eec ff t of initial pH on BaP adsorption The mineral, organic and biotic composition of surface waters depends on the source and geographic location, which in turn affects the water pH and influences the adsorp- tion of chemical pollutants (Kulthanan et al. 2013). Solution pH affects the net charge of the adsorbent and adsorbate, and the alterations are more impactful in compounds and materials with protonated moieties (–OH, –COOH, –NH Fig. 3 Effect of pH on BaP adsorption onto GW-αAgNP (Experi- group, etc.) because they tend to form deprotonated groups/ mental conditions: C = 300  µg/L; dosage = 5  mg per 5  mL, mixing complexes under variable pH conditions (Ahmed & Gas- rate = 200  rpm, T = 25 ± 1  °C, contact time: 24  h). Error bars ± rela- tive standard deviation (RSD), n = 3 ser 2012). In principle, at pH < point of zero charge (PZC), the surface of the adsorbent is positively charged and at pH > PZC, sorbents become negatively charged (Liikanen et  al. 2006; Ololade et al. 2018). The results obtained in Influence of NOM on sorbent‑sorbate interaction this study revealed that the optimum adsorption of BaP by GW-αAgNP occurred under basic pH conditions. This is in Natural organic matter (NOM) is a complex matrix of contrast to GW adsorption of PAHs that was slightly favored organic materials which are present in aquatic environ- under acidic pH (Adeola & Forbes 2019). ments, including drinking water, due to the interconnectiv- Figure 3 reveals that the adsorption is favored to the right ity between the hydrologic cycle, biosphere, and geosphere side of the pH scale due to the nature of the oleylamine- within the ecosystem (Sillanpää et al. 2018). The compo- capped AgNP-GW complex, the surface modification, and sition of NOM is influenced by biogeochemical processes the abundance of hydroxide ions in basic pH that potentially that have occurred within the environment (Myneni 2019). facilitates hydrogen bonding as discussed in Sect. 3.2. Fur- In this study, NOM was isolated from stream sediment col- thermore, excess hydroxide ions at pH > 7 could potentially lected from the University of Pretoria sports campus, South lead to the formation of silver hydroxide, which is hydro- Africa (latitude E28° 14′ 46′′ and longitude S25° 45′ 10′′) phobic and thus enhances the more hydrophobic interac- using established procedures (Ran et  al. 2007; Ololade tions with BaP, which often governs the adsorption and et  al. 2018; Adeola & Forbes 2021a). The mineral phase partitioning of hydrophobic organic compounds (HOC) in was removed from bulk samples via treatment with 1 N HCl water (Vasileva et al. 2009; Apul et al. 2013; Bai et al. 2017; for 45 min at ambient temperature, followed by three con- Adeola & Forbes 2020, 2021b). secutive treatments with 1 N HCl and 10% HN O for 12 h 1 3 172 Page 8 of 15 Applied Water Science (2021) 11:172 experiment (Adeola & Forbes 2021a; Ersan et al. 2016). Fig- ure 5 suggests that significant competitive interactions took place between the NOM, BaP molecules, and the adsorbent leading to the comparative decline in removal efficiency, Freundlich adsorption capacity (K ), partition coefficient (K ), and maximum adsorption capacity (q ). NOM has d max been reported to cause fouling of membranes, and reten- tion of hydrophobic compounds and metals in solution, thus limiting the efficiency of conventional water treatment plants (Mehta et al. 2017; Kurwadkar et al. 2019; Adeola & Forbes 2021b). Essentially, NOM often alters the solution’s chemis- try such as pH, ionic strength, and the presence of leachable trace and heavy metals (Fig. 4), providing a plausible expla- nation for the inhibitory role of NOM (Ersan et al. 2016; Lamichhane et al. 2016; Adeola & Forbes 2021a). Fig. 4 Physicochemical properties and morphology of NOM isolate. Elemental composition was determined using ICP-OES. a Optical Eec ff t of temperature and thermodynamic studies image and b SEM image of NOM (200 nm) Several physicochemical and biological processes are (Gelinas et al. 2001). The residue was washed each time with influenced by temperature. Therefore, the role of tempera - DI water, centrifuged at 6000 rpm for 10 min, decanted, and ture on the adsorption of BaP by pristine GW and doped freeze-dried at − 4 C for 24 h prior to use. Morphological GW-αAgNP was studied at 35, 45, and 55 °C, respectively. and basic characterization of the NOM was carried out as The adsorption data were fit to a linear and Sips isotherm presented in Fig. 4 (see Adeola and Forbes 2021b for more models (Eq. 3 and 6), and it was observed that the maxi- details). The NOM isolate had an irregular, spherical grain mum adsorption capacity (q ) significantly reduced for structure with heterogeneous and porous surface morphol- GW-αAgNP with an increase in temperature, while the ogy (Fig. 4). reverse was observed for GW (Table 3, Fig. 6). The free The effect of NOM on the adsorption of BaP by energy change (ΔG˚), enthalpy (ΔH˚) and entropy (ΔS˚) GW-αAgNP was evaluated using a preloading batch were calculated using the Van’t Hoff plot and equations Fig. 5 Influence of NOM on the removal efficiency and adsorption capacity of benzo(a) pyrene by GW-αAgNP. (Experimental conditions: C = 100—500 µg/L; o (BaP) sorbent dosage = 1 g/L, NOM dosage = 1 g/L, mixing rate = 200 rpm, T = 25 ± 1 °C, contact time: 24 h) Table 3 Thermodynamic parameters for adsorption of BaP onto graphene wool and doped graphene wool Temp. (K) GW GW-αAgNP ΔG˚ (J/mol) ΔH˚ (kJ/mol) ΔS˚ (kJ/mol.K) *q (µg/g) ΔG˚ (J/mol) ΔH˚ (kJ/mol) ΔS˚ (kJ/mol.K) *q (µg/g) m m 298 50.02 59.75 −2507.55 97.62 308 −2560.71 94.42 0.32 63.09 −1636.57 −24.04 −0.07 84.14 318 −6296.06 66.36 −1065.57 76.88 q : maximum adsorption capacity derived from Sips model 1 3 Applied Water Science (2021) 11:172 Page 9 of 15 172 Table 3 revealed positive values of adsorption enthalpy ◦ ◦ ( ΔH ) and entropy (ΔS ), and a negative value of ΔG for GW-BaP interaction, which indicates a spontaneous endo- thermic process as the temperature increased (Ahmed & Gasser 2012). This result is in agreement with a previous study on the adsorption of phenanthrene and pyrene by GW (Adeola & Forbes 2019). In contrast, GW-αAgNP-BaP inter- action is a spontaneous exothermic process (negative ΔH and ΔG), with a reduction in system chaos (negative ΔS ) and adsorption capacity as the temperature is increased. While GW is more efficient at elevated temperatures, doping GW with oleylamine-capped AgNPs improved the adsorp- tion capacity and ensured optimum removal efficiency at ambient temperature, which is better in terms of energy eco- nomics and industrial application. Fig. 6 Van’t Hoff equation for BaP adsorption onto GW and Antibacterial activity of GW‑αAgNP GW-αAgNP from aqueous solution Silver nanoparticles and composites have attracted scientific (eqs. 8 and 9) (Fig. 6), in order to elucidate the thermody- attention due to the continuous upsurge of drug-resistant namic nature of adsorption of BaP as a function of temper- bacteria (Bezza et al. 2020; Cobos et al. 2020). Bacterial ature (Yakout & Daifullah 2013; Adeola & Forbes 2019). strains are classified as Gram-positive (G + ve) or Gram- negative (G-ve) based on film assemblage with layers of ◦ ◦ ΔS ΔH lnK = − (8) peptidoglycan (PG) (Proft and Baker 2009). G − ve microbes R RT have a thin PG (1–5 nm) between the cytoplasmic film and external layer, while G + ve microbes have a thicker PG ◦ ◦ ◦ ΔG =ΔH − TΔS (9) layer (~ 30 nm) without an external film (Kim et al. 2007). The mechanism of action of silver-containing materials is where ΔG is the change in the Gibbs free energy (cal/mol); described in Fig. 7. Silver damages the cytoplasmic mem- ΔH is the change in enthalpy (cal/mol), and ΔS is the change brane of microbes, creates oxidative stress with the cells, in entropy (kJ/mol.K), R = gas constant (8.314 J/mol.K), damages DNA, denatures cell proteins and has a lethal T = thermodynamic temperature (K) and K is adsorption effect on microorganisms, including drug-resistant bacteria capacity determined from the linear isotherm model. (Ahmad et al. 2020). Fig. 7 A plausible mechanism for the antimicrobial action of silver nanoparticles. (Repro- duced with permission from Ahmad et al. Copyright 2020, Elsevier) 1 3 172 Page 10 of 15 Applied Water Science (2021) 11:172 Several studies have established the antibacterial action contamination in aqueous media has gained vast attention of AgNPs and composites, with different minimum inhibi- (Liu et al. 2011; Loan Khanh et al. 2019; Bezza et al. 2020). tory concentrations against some drug-resistant microbes The antibacterial activity of GW-αAgNPs and pristine (Table  4). The minimum inhibitory concentration (MIC) AgNPs was tested against the Gram-negative Pseudomonas is regarded as the lowest concentration of an antimicrobial aeruginosa CB1 and Gram-positive Bacillus subtilis CN2 agent that inhibits the growth of microbes, recorded in mg/L strains by the standard micro-dilution method. Earlier or μg/mL (Cobos et al. 2020). The literature suggests that reports suggest that P. aeruginosa and B. subtilis strains are AgNPs and bimetallic nanocomposites (such as Au–Ag, capable of adaptive resistance to antibiotics such as penicil- Fe-Ag) are more effective against microorganisms based on lin and tetracycline (Araya et al. 2019; Pang et al. 2019). MIC values; however, the potential adverse effects of AgNPs Figure 8 reveals a dose-dependent reduction in the concen- on human health have been a major concern, hence research tration of Gram-negative Pseudomonas aeruginosa CB1 into stabilizing AgNPs using capping agents and entrap- and Gram-positive Bacillus subtilis CN2 strains after 24 h ment within a bulky substrate to limit its release potential/ incubation period as a decrease in turbidity was recorded Table 4 A brief summary of silver-containing composites and microorganisms inhibited along with their minimum inhibitory concentrations (MIC) as reported in the literature (mg/L) Composite Microbes Minimum inhibitory References concentration (mg/L) AgNPs/starch/sodium alginate/lemon- Escherichia coli Not reported Maizura et al. (2007) grass oil a a b Sodium Alginate/AgNPs Staphylococcus aureus, 80, 40 Mohammed Fayaz et al. (2009) Escherichia coli a a b c d Silver nanocomposites Staphylococcus aureus, 250, 62.5, 125, 2000 Egger et al. (2009) Escherichia coli, Candida albicans, Aspergillus niger a a b c Bimetallic Au@Ag core–shell nanopar- Escherichia coli, 1.56, 1.88, 2.5 Banerjee et al. (2011) ticles Pseudomonas aeruginosa, Enterococcus faecalis AgNP-Bovin serum albumin (BSA) Staphylococcus aureus, 469.2 Espinosa-Cristóbal et al. (2015) Escherichia coli, Enterococcus faecalis Polycaprolactone-silver composites Escherichia coli, Staphylococcus aureus, 12.5 Pazos-Ortiz et al. (2017) (PCL-AgNPs) Pseudomonas aeruginosa a b a b c Ag-microfibrillated cellulose biocom- Escherichia coli, Staphylococcus 125, 1500, 125 Garza-Cervantes et al. (2020) posite aureus, Pseudomonas aeruginosa Chitosan-AgNP Staphylococcus aureus 32.98 Quintero-Quiroz et al. (2020) a a,b c d Ag–Fe bimetallic nanoparticles Staphylococcus aureus, 125, 62.5, 31.23 Padilla-Cruz et al. (2021) Escherichia coli, Candida albicans, Pseudomonas aeruginosa Graphene oxide-AgNP Staphylococcus aureus, Not reported Jaworski et al. (2018) b b,d a,c Escherichia coli, 64, 32 Cobos et al. (2020) Candida albicans, Pseudomonas aeruginosa AgNP Staphylococcus aureus, < 8.0 Gurunathan (2019); Loo et al. Escherichia coli, 10–12 (2018) c abc d Candida albicans, 125, 62.5 Dong et al. (2019); Vazquez- Pseudomonas aeruginosa Muñoz et al. (2019) Padilla-Cruz et al. (2021) Gelatin-stabilized AgNPs and curcumin Staphylococcus aureus, Pseudomonas 125 Loan Khanh et al. (2019) aeruginosa Lipopetide-capped AgNP Pseudomonas aeruginosa, 15.63 Bezza et al. (2020) Bacillus subtillis Graphene wool doped with oleylamine- Pseudomonas aeruginosa, 1000 This study capped AgNPs Bacillus subtillis 1 3 Applied Water Science (2021) 11:172 Page 11 of 15 172 Fig. 8 Visible antibacterial activity of composites a 500 and determined spectrophotometrically at an optical density of 600  nm 1000  mg/L of GW-αAgNP in 100  mL TSB nutrient medium inocu- (OD ), n = 2. (100  mL TSB nutrient medium inoculated with P. 600nm lated with P. aeruginosa (left) and B. subtilis (right) b 1000 mg/L of aeruginosa and B. subtilis without GW or GW-αAgNP were included GW in 100 mL TSB nutrient medium inoculated with P. aeruginosa as controls) and B. subtilis c Variation in concentration of respective bacteria spectrophotometrically at an optical density of 600 nm. The adsorptive properties of GW-αAgNP suggest that the mate- decline in turbidity is a function of bacteriostatic/bacteri- rial may be suitable for the fabrication of adsorbent layer(s) cidal activity of the composite, relative to control experi- in water filtration or purification devices. ments. The reduction is most significant at 1000  mg/L (GW-αAgNP) and was more visible in doped GW than pristine GW. Factors such as particle size, stabilizing agent, Conclusion composition of culture media and bacteria type, inoculum size, and leachability of silver ions from the composite, play Facile synthesis of GW doped with oleylamine-capped a critical role in determining the MIC values. Optical density AgNPs was achieved in this study. The effect of concen- measurement is the most common technique for determining tration, pH, and temperature on the adsorption of benzo(a) bacteria concentration and efficacy of antibacterial agents pyrene, a human carcinogen, was evaluated using the doped (McBirney et al. 2016; Huang et al. 2017). The agar disk graphene wool. Isotherm data suggest that GW-αAgNP-BaP diffusion test is another method often used for nanoparti- interaction is a spontaneous exothermic process (negative cles that are dispersible in water to form a uniform solu- ΔH and ΔG), characterized by a decline in system chaos tion, however, due to the macroscopic and fibrous nature (negative ΔS ) and adsorption capacity as temperature of GW, it was impossible to obtain a uniform dispersion of increases. This study suggests that the adsorption capac- the material in the solution. When such experiments were ity of GW improved and will be more efficient at ambient attempted, the release and mobility of silver ions from the temperature ( ΔG and q ), when doped with AgNPs as a max macrostructure through the semi-solid agar were signifi - result of improved surface hydrophobicity and heterogene- cantly limited, thus constricting the inhibition zone to the ity, leading to the creation of more binding sites for BaP to site of deposition on the plate (Fig. 9), a similar finding was adhere to. Results revealed a high degree of desorption hys- reported for large-sized AgNPs (Xiu et al. 2012; Bezza et al. teresis and irreversible sorption, suggesting a strong binding 2020). However, the texture, fibrous nature, antibacterial and strength between the doped GW and pollutant, thus limiting 1 3 172 Page 12 of 15 Applied Water Science (2021) 11:172 Fig. 9 Agar disk diffusion test a Before incubation- 100 mg of GW-αAgNP was placed on agar disk with growth medium and Bacillus subtilis culture spread over uniformly, b After 24 h incubation- visible growth of the bacteria around GW-αAgNP with inhibition zone limited to the site of deposition Open Access This article is licensed under a Creative Commons Attri- the ease of recontamination. Results also show that the pres- bution 4.0 International License, which permits use, sharing, adapta- ence of NOM in the aqueous matrix is undesirable for the tion, distribution and reproduction in any medium or format, as long application of the synthesized adsorbent due to competitive as you give appropriate credit to the original author(s) and the source, adsorption. Several studies have established the cytoplas- provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are mic toxicity and antimicrobial properties of silver-contain- included in the article's Creative Commons licence, unless indicated ing nanomaterials and in this study, preliminary results also otherwise in a credit line to the material. If material is not included in revealed that there was a dose-dependent reduction in the the article's Creative Commons licence and your intended use is not concentration of Gram-negative Pseudomonas aeruginosa permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a CB1 and Gram-positive Bacillus subtilis CN2 strains tested copy of this licence, visit http://cr eativ ecommons. or g/licen ses/ b y/4.0/ . in the presence of GW-αAgNP. Furthermore, unlike most composites that are generated in the form of flakes or powder, GW-αAgNP provides a wool-like form that may be more suitable as a packing mate- References rial for filters and other water polishing tools due to its light- Adeniji AO, Okoh OO, Okoh AI (2019) Levels of Polycyclic aromatic weight and porous nature. The synthesis of graphene wool is hydrocarbons in the water and sediment of buffalo river estuary, facile and eco-friendly without extensive use of chemicals. south africa and their health risk assessment. Arch Environ Con- Therefore, under appropriate operating conditions, the gra- tam Toxicol 76(4):657–669 phene-based composite can potentially be utilized as a water Adeola AO, Forbes PBC (2019) Optimization of the sorption of selected polycyclic aromatic hydrocarbons by regenerable gra- polishing tool for the removal of emerging organic chemical phene wool. Water Sci Technol 80:1931–1943 pollutants. With further studies and suitable fabrication, this Adeola AO, Forbes PBC (2020) Assessment of reusable graphene hybrid material has the potential to serve as a smart solution wool adsorbent for the simultaneous removal of selected 2–6 to chemical and microbial pollution in water. ringed polycyclic aromatic hydrocarbons from aqueous solu- tion. Environ Technol. https://doi. or g/10. 1080/ 09593 330. 2020. 18240 24 Acknowledgements Authors acknowledge the assistance provided by Adeola AO, Forbes PBC (2021a) Influence of natural organic matter Dr F. A. Bezza during the antibacterial testing of the composite, the fractions on PAH sorption by stream sediments and a synthetic University of Pretoria Commonwealth Doctoral Scholarship funding graphene wool adsorbent. Environ Technol Innov 21:101202 (AA) and the Rand Water Professorial Chair program (PF and EC) for Adeola AO, Forbes PBC (2021b) Advances in water treatment tech- providing funding for the research. nologies for removal of polycyclic aromatic hydrocarbons: existing concepts, emerging trends, and future prospects. Water Funding This study is supported by University of Pretoria Common- Environ Res 93:343–395 wealth Doctoral Scholarship funding (AA) and the Rand Water Profes- Ahmad HB, Yasmin GE, Arain SA, Bhatti IA, Hussain M (2015) sorial Chair program (PF and EC). Synthesis of some novel adsorbents for antimicrobial activity and removal of arsenic from drinking water. Korean J Chem Declarations Eng 32:661–666 Ahmad SA, Sachi Das S, Khatoon A, Tahir Ansari M, Afzal M, Saquib Hasnain M, Kumar Nayak A (2020) Bactericidal activity Conflict of interest The authors declare that there is no conflict of in- of silver nanoparticles: a mechanistic review. Mater Sci Energy terest. Technologies 3:756–769 Ahmed IM, Gasser MS (2012) Adsorption study of anionic reac- Ethical approval This article does not contain any studies with human tive dye from aqueous solution to Mg-Fe-CO layered double participants or animals performed by any of the authors. hydroxide (LDH). Appl Surf Sci 259:650–656 1 3 Applied Water Science (2021) 11:172 Page 13 of 15 172 Amari A, Elboughdiri N, Ghernaout D, Lajimi RH, Alshahrani AM, Ersan G, Kaya Y, Apul OG, Karanfil T (2016) Adsorption of organic Tahoon MA, Rebah FB (2021) Multifunctional crosslinked contaminants by graphene nanosheets, carbon nanotubes and chitosan/nitrogen-doped graphene quantum dot for wastewater granular activated carbons under natural organic matter preload- treatment. Ain Shams Eng J. https://doi. or g/10. 1016/j. asej. 2021. ing conditions. Sci Total Environ 565:811–817 02. 024 Espinosa-Cristóbal LF, Martínez-Castañón GA, Loyola-Rodríguez JP, Amstaetter K, Eek E, Cornelissen G (2012) Sorption of PAHs and Niño-Martínez N, Ruiz F, Zavala-Alonso NV, Lara RH, Reyes- PCBs to activated carbon: coal versus biomass-based quality. López SY (2015) Bovine serum albumin and chitosan coated sil- Chemosphere 87:573–578 ver nanoparticles and its antimicrobial activity against oral and Anthony KJP, Murugan M, Gurunathan S (2014) Biosynthesis of nonoral bacteria. J Nanomater, 420853 silver nanoparticles from the culture supernatant of Bacillus Fayaz AM, Balaji K, Girilal M, Kalaichelvan PT, Venkatesan R (2009) marisflavi and their potential antibacterial activity. J Ind Eng Mycobased synthesis of silver nanoparticles and their incorpora- Chem 20:1505–1510 tion into sodium alginate films for vegetable and fruit preserva- Apul OG, Wang Q, Zhou Y, Karanfil T (2013) Adsorption of aromatic tion. J Agric Food Chem 57:6246–6252 organic contaminants by graphene nanosheets: comparison with Garza-Cervantes JA, Mendiola-Garza G, de Melo EM, Dugmore TIJ, carbon nanotubes and activated carbon. Water Res 47:1648–1654 Matharu AS, Morones-Ramirez JR (2020) Antimicrobial activity Araya G, Benites J, Reyes JS, Marcoleta AE, Valderrama JA, Lagos of a silver-microfibrillated cellulose biocomposite against suscep- R, Monasterio O (2019) Inhibition of Escherichia coli and tible and resistant bacteria. Sci Rep 10:7281 Bacillus subtilis FtsZ Polymerization and Bacillus subtilis Gelinas Y, Prentice KM, Baldock JA, Hedges J (2001) An improved Growth by Dihydroxynaphtyl Aryl Ketones. Front Microbiol thermal oxidation method for the quantification of soot/graphite 10:1225. https:// doi. org/ 10. 3389/ fmicb. 2019. 01225 carbon in sediments and soils. Environ Sci Technol 21:3519–3525 Bai H, Zhou J, Zhang H, Tang G (2017) Enhanced adsorbability and Gurunathan S (2019) Rapid biological synthesis of silver nanoparti- photocatalytic activity of TiO -graphene composite for polycy- cles and their enhanced antibacterial effects against Escherichia clic aromatic hydrocarbons removal in aqueous phase. Colloids fergusonii and Streptococcus mutans. Arab J Chem 12:168–180 Surf, B 150:68–77 Hardonnière K, Saunier E, Lemarié A, Fernier M, Gallais I, Héliès- Banerjee M, Sharma S, Chattopadhyay A, Ghosh SS (2011) Enhanced Toussaint C, Mograbi B, Antonio S, Bénit P, Rustin P, Janin M, antibacterial activity of bimetallic gold-silver core-shell nanopar- Habarou F, Ottolenghi C, Lavault M-T, Benelli C, Sergent O, Huc ticles at low silver concentration. Nanoscale 3:5120–5125 L, Bortoli S, Lagadic-Gossmann D (2016) The environmental car- Bezza FA, Chirwa EMN (2016) Biosurfactant-enhanced bioremedia- cinogen benzo[a]pyrene induces a Warburg-like metabolic repro- tion of aged polycyclic aromatic hydrocarbons (PAHs) in creosote gramming dependent on NHE1 and associated with cell survival. contaminated soil. Chemosphere 144:635–644 Sci Rep 6:30776 Bezza FA, Tichapondwa SM, Chirwa EMN (2020) Synthesis of bio- Hassan SSM, Abdel-Shafy HI, Mansour MSM (2018) Removal of pyr- surfactant capped silver nanoparticles characterization and their ene and benzo(a)pyrene micropollutant from water via adsorption potential application for bactericidal purposes. J Hazard Mater by green synthesized iron oxide nanoparticles. advances in Natu- 393:122319 ral Sciences. Nanosci Nanotechnol 9(1):015006 Bushra R, Shahadat M, Ahmad A, Nabi SA, Umar K, Oves M, Raeissi Huang W, Wang J-Q, Song H-Y, Zhang Q, Liu G-F (2017) Chemi- AS, Muneer M (2014) Synthesis, characterization, antimicrobial cal analysis and in vitro antimicrobial effects and mechanism of activity and applications of polyanilineTi(IV)arsenophosphate action of Trachyspermum copticum essential oil against Escheri- adsorbent for the analysis of organic and inorganic pollutants. J chia coli. Asian Pac J Trop Med 10:663–669 Hazard Mater 264:481–489 IARC, International Agency for Research on Cancer, (2010) IARC Çınar S, Gündüz G, Mavis B, Çolak U (2011) Synthesis of silver nano- Monographs on the Evaluation of Carcinogenic Risks to Humans. particles by Oleylamine-Oleic acid reduction and its use in mak- (Lyon: World Health Organization) 92, 1–853 ing nanocable by coaxial electrospinning. J Nanosci Nanotechnol Ilyas M, Ahmad W, Khan H (2021) Utilization of activated carbon 11:3669–3679 derived from waste plastic for decontamination of polycyclic Cobos M, De-La-Pinta I, Quindós G, Fernández MJ, Fernández MD aromatic hydrocarbons laden wastewater. Water Sci Technol (2020) Graphene oxide-silver nanoparticle nanohybrids: synthe- 84:609–631 sis, characterization, and antimicrobial properties. Nanomaterials Ishihara M, Nguyen VQ, Mori Y, Nakamura S, Hattori H (2015) 10(2):376 Adsorption of silver nanoparticles onto different surface structures Cornelissen G, Gustafsson Ö, Bucheli TD, Jonker MTO, Koelmans of chitin/chitosan and correlations with antimicrobial activities. AA, van Noort PCM (2005) Extensive sorption of organic com- Int J Mol Sci 16:13973–13988 pounds to black carbon, coal, and kerogen in sediments and soils: Jaworski S, Wierzbicki M, Sawosz E, Jung A, Gielerak G, Biernat J, mechanisms and consequences for distribution, bioaccumulation, Jaremek H, Łojkowski W, Woźniak B, Wojnarowicz J, Stobiński and biodegradation. Environ Sci Technol 39:6881–6895 L, Małolepszy A, Mazurkiewicz-Pawlicka M, Łojkowski M, Dana E, Taha A, Afkar E (2018) Green synthesis of iron nanoparticles Kurantowicz N, Chwalibog A (2018) Graphene oxide-based nano- by acacia nilotica pods extract and its catalytic, adsorption, and composites decorated with silver nanoparticles as an antibacterial antibacterial activities. Appl Sci 8:1922 agent. Nanoscale Res Lett 13:116 Dong Y, Zhu H, Shen Y, Zhang W, Zhang L (2019) Antibacterial activ- Jyoti K, Baunthiyal M, Singh A (2016) Characterization of silver nano- ity of silver nanoparticles of different particle size against Vibrio particles synthesized using Urtica dioica Linn. leaves and their Natriegens. PLOS ONE, 14, e0222322 synergistic effects with antibiotics. J Rad Res Appl Sci 9:217–227 Egger S, Lehmann RP, Height MJ, Loessner MJ, Schuppler M (2009) Khan E, Khaodhir S, Rotwiron P (2007) Polycyclic aromatic hydrocar- Antimicrobial properties of a novel silver-silica nanocomposite bon removal from water by natural fiber sorption. Water Environ material. Appl Environ Microbiol 75:2973 Res 79:901–911 Eltugral N, Simsir H, Karagoz S (2016) Preparation of nano-silver- Kim JS, Kuk E, Yu KN, Kim J-H, Park SJ, Lee HJ, Kim SH, Park YK, supported activated carbon using different ligands. Res Chem Park YH, Hwang C-Y, Kim Y-K, Lee Y-S, Jeong DH, Cho M-H Intermed 42:1663–1676 (2007) Antimicrobial effects of silver nanoparticles. Nanomed Nanotechnol Biol Med 3:95–101 1 3 172 Page 14 of 15 Applied Water Science (2021) 11:172 Kulthanan K, Nuchkull P, Varothai S (2013) The pH of water from matter towards adsorption and desorption of phenol and its chlo- various sources: an overview for recommendation for patients rinated derivatives. J Environ Chem Eng 6:3485–3494 with atopic dermatitis. Asia Pac Allergy 3:155–160 Padilla-Cruz AL, Garza-Cervantes JA, Vasto-Anzaldo XG, García- Kurwadkar S, Hoang TV, Malwade K, Kanel SR, Harper WF, Struck- Rivas G, León-Buitimea A, Morones-Ramírez JR (2021) Syn- hoff G (2019) Application of carbon nanotubes for removal of thesis and design of Ag–Fe bimetallic nanoparticles as antimicro- emerging contaminants of concern in engineered water and waste- bial synergistic combination therapies against clinically relevant water treatment systems. Nanotechnol Environ Eng 4(1):1–16 pathogens. Sci Rep 11:5351 Lamichhane S, Bal Krishna KC, Sarukkalige R (2016) Polycyclic Pang Z, Raudonis R, Glick BR, Lin T-J, Cheng Z (2019) Antibiotic aromatic hydrocarbons (PAHs) removal by sorption: A review. resistance in Pseudomonas aeruginosa: mechanisms and alterna- Chemosphere 148:336–353 tive therapeutic strategies. Biotechnol Adv 37:177–192 Li H, He N, Cheng C, Dong H, Wen J, Wang X (2020) Antimicrobial Pazos-Ortiz E, Roque-Ruiz JH, Hinojos-Márquez EA, López-Esparza polymer contained adsorbent a promising candidate with remark- J, Donohué-Cornejo A, Cuevas-González JC, Espinosa-Cristóbal able anti-biofouling ability and durability for enhanced uranium LF, Reyes-López SY (2017) Dose-dependent antimicrobial activ- extraction from seawater. Chem Eng J 388:124273 ity of silver nanoparticles on polycaprolactone fibers against Liikanen R, Yli-Kuivila J, Tenhunen J, Laukkanen R (2006) Cost and gram-positive and gram-negative bacteria. J Nanomater. https:// environmental impact of nanofiltration in treating chemically pre-doi. org/ 10. 1155/ 2017/ 47523 14 treated surface water. Desalination 201:58–70 Pérez-Gregorio MR, García-Falcón MS, Martínez-Carballo E, Simal- Liu L, Liu J, Wang Y, Yan X, Sun DD (2011) Facile synthesis of Gándara J (2010) Removal of polycyclic aromatic hydrocar- monodispersed silver nanoparticles on graphene oxide sheets with bons from organic solvents by ashes wastes. J Hazard Mater enhanced antibacterial activity. New J Chem 35:1418–1423 178:273–281 Loan Khanh L, Thanh Truc N, Tan Dat N, Thi Phuong NN, van Toi V, Prakash P, Gnanaprakasam P, Emmanuel R, Arokiyaraj S, Saravanan M Thi Thu HN, Ngoc Quyen T, Thi Thanh LT, Thi Hiep N (2019) (2013) Green synthesis of silver nanoparticles from leaf extract of Gelatin-capped composites of silver nanoparticles and curcumin: Mimusops elengi, Linn. for enhanced antibacterial activity against characterization, antibacterial and antioxidant study. Sci Technol multi drug resistant clinical isolates. Colloids Surf B 108:255–259 Adv Mater 20:276–290 Proft T, Baker EN (2009) Pili in Gram-negative and Gram-positive Loo YY, Rukayadi Y, Nor-Khaizura M-A-R, Kuan CH, Chieng BW, bacteria—structure, assembly and their role in disease. Cell Mol Nishibuchi M, Radu S (2018) In vitro antimicrobial activity of Life Sci 66:613. https:// doi. org/ 10. 1007/ s00018- 008- 8477-4 green synthesized silver nanoparticles against selected gram- Quintero-Quiroz C, Botero LE, Zárate-Triviño D, Acevedo-Yepes N, negative foodborne pathogens. Front Microbiol. https:// doi. org/ Escobar JS, Pérez VZ, Cruz Riano LJ (2020) Synthesis and char- 10. 3389/ fmicb. 2018. 01555 acterization of a silver nanoparticle-containing polymer compos- Maizura M, Fazilah A, Norziah MH, Karim AA (2007) Antibacterial ite with antimicrobial abilities for application in prosthetic and activity and mechanical properties of partially hydrolyzed sago orthotic devices. Biomater Res 24:13 starch-alginate edible film containing lemongrass oil. J Food Sci Ran Y, Sun K, Ma X, Wang GH, Grathwohl P, Zeng EY (2007) Effect 72:C324–C330 of condensed organic matters on solvent extraction and aqueous McBirney SE, Trinh K, Wong-Beringer A, Armani AM (2016) Wave- leaching of PAHs based in soils and sediments. J Environ Poll length-normalized spectroscopic analysis of Staphylococcus 43:111–123 aureus and Pseudomonas aeruginosa growth rates. Biomed Opt Schinwald A, Murphy FA, Jones A, MacNee W, Donaldson K (2012) Express 7:4034–4042 Graphene-based nanoplatelets: a new risk to the respiratory sys- Mehta R, Saha NK, Bhattacharya A (2017) Pretreatment of agriculture tem as a consequence of their unusual aerodynamic properties. e fi ld water for improving membrane u fl x during pesticide removal. ACS Nano 6:736–746 Appl Water Sci 7:3281–3290 Schoonraad G, Madito MJ, Manyala N, Forbes PBC (2020) Syn- Minkina T, Vasilyeva G, Popileshko Y, Bauer T, Sushkova S, thesis and optimisation of a novel graphene wool material by Fedorenko A, Antonenko E, Pinskii D, Mazarji M, Ferreira atmospheric pressure chemical vapour deposition. J Mater Sci CSS (2021) Sorption of benzo[a]pyrene by Chernozem and 55:545–564 carbonaceous sorbents: comparison of kinetics and interaction Sears GW (1956) Determination of specific surface area of colloidal sil- mechanisms. Environ Geochem Health. https:// doi. org/ 10. 1007/ ica by titration with sodium hydroxide. Anal Chem 28:1981–1983 s10653- 021- 00945-8 Sha L, Guanying C, Paras NP, Mark TS (2011) Synthesis of Monodis- Miren J, Aurora M-B, Ulrich K, Tomas G-A (2018) Smart and multi- perse Au, Ag, and AuAg alloy nanoparticleswith tunable size and functional materials and their possible application in façade sys- surface plasmon resonance frequency. Chem Mater 23:4098–4101 tems. J Facade Des Eng 6:19–33 Sillanpää M, Ncibi MC, Matilainen A (2018) Advanced oxidation Mojahed F, Dehghanpour S, Alizadeh M, Mahmoudi A (2011) Wet processes for the removal of natural organic matter from drink- chemical synthesis of oleylamine-capped silver nanoparticles by a ing water sources: a comprehensive review. J Environ Manage fast and facile reproducible method. Synth React Inorg, Met-Org, 208:56–76 Nano-Met Chem 41:664–670 Tran M-H, Jeong HK (2015) Synthesis and characterization of silver Munyeza CF, Osano AM, Maghanga JK, Forbes PBC (2020) Polycyclic nanoparticles doped reduced graphene oxide. Chem Phys Lett aromatic hydrocarbon gaseous emissions from household cooking 630:80–85 devices: a kenyan case study. Environ Toxicol Chem 39:538–547 Vasileva SY, Olenin AY, Romanovskaya GI, Krutyakov YA, Pogonin Myneni SCB (2019) Chemistry of natural organic matter—the next VI, Korotkov AS, Zuev BK (2009) Adsorption preconcentration step: commentary on a humic substances debate. J Environ Qual of pyrene by silver nanoparticles and its determination in aqueous 48:233–235 solutions. J Anal Chem 64:1214–1220 Nguyen TH, Sabbah I, Ball WP (2004) Sorption nonlinearity for Vazquez-Muñoz R, Meza-Villezcas A, Fournier PGJ, Soria-Castro E, organic contaminants with diesel soot: method development and Juarez-Moreno K, Gallego-Hernández AL, Bogdanchikova N, isotherm interpretation. Environ Sci Technol 38:3595–3603 Vazquez-Duhalt R, Huerta-Saquero A (2019) Enhancement of Ololade IA, Adeola AO, Oladoja NA, Ololade OO, Nwaolisa SU, antibiotics antimicrobial activity due to the silver nanoparticles Alabi AB, Ogungbe IV (2018) In-situ modification of soil organic impact on the cell membrane. PLOS ONE, 14, e0224904 1 3 Applied Water Science (2021) 11:172 Page 15 of 15 172 Wang L, Niu J, Yang Z, Shen Z, Wang J (2008) Effects of carbonate and simultaneous ozonation and biotreatment. Water Environ Res and organic matter on sorption and desorption behavior of polycy- 78:2286–2292 clic aromatic hydrocarbons in the sediments from Yangtze River. Yuan P, Li X, Wang W, Liu H, Yan Y, Yang H, Yue Y, Bao X (2018) J Hazard Mater 154:811–817 Tailored design of differently modified mesoporous materials to Wang W, Wang Z, Liu J, Zhang Z, Sun L (2017) Single-step one-pot deeply understand the adsorption mechanism for polycyclic aro- synthesis of graphene foam/TiO2 nanosheet hybrids for effective matic hydrocarbons. Langmuir 34:15708–15718 water treatment. Sci Rep 7:43755 Zhang C, Wu L, Cai D, Zhang C, Wang N, Zhang J, Wu Z (2013) Wang S, Li X, Liu Y, Zhang C, Tan X, Zeng G, Song B, Jiang L Adsorption of polycyclic aromatic hydrocarbons (fluoranthene (2018) Nitrogen-containing amino compounds functionalized and anthracenemethanol) by functional graphene oxide and graphene oxide: Synthesis, characterization and application for removal by ph and temperature-sensitive coagulation. ACS Appl the removal of pollutants from wastewater: a review. J Hazard Mater Interf 5:4783–4790 Mater 342:177–191 Zhang W, Yang Z-Y, Cheng X-W, Tang R-C, Qiao Y-F (2019) Adsorp- Xiu ZM, Zhang QB, Puppala HL, Colvin VL, Alvarez PJ (2012) Negli- tion, antibacterial and antioxidant properties of tannic acid on silk gible particle-specific antibacterial activity of silver nanoparticles. fiber. Polymers 11(6):970 Nano Lett 12:4271–4275 Zhao G, Jiang L, He Y, Li J, Dong H, Wang X, Hu W (2011) Sul- Yakout SM, Daifullah AAM (2013) Removal of selected polycyclic fonated graphene for persistent aromatic pollutant management. aromatic hydrocarbons from aqueous solution onto various adsor- Adv Mater 23:3959–3963 bent materials. Desalin Water Treat 51:6711–6718 Yang K, Chen B, Zhu L (2015) Graphene-coated materials using silica Publisher's Note Springer Nature remains neutral with regard to particles as a framework for highly efficient removal of aromatic jurisdictional claims in published maps and institutional affiliations. pollutants in water. Sci Rep 5:11641 Yerushalmi L, Nefil S, Hausler R, Guiot SR (2006) Removal of pyr - ene and benzo(a)Pyrene from contaminated water by sequential 1 3 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Applied Water Science Springer Journals

Facile synthesis of graphene wool doped with oleylamine-capped silver nanoparticles (GW-αAgNPs) for water treatment applications

Download PDF
15 pages

Loading next page...
 
/lp/springer-journals/facile-synthesis-of-graphene-wool-doped-with-oleylamine-capped-silver-CzcmO1JKfZ

References (90)

Publisher
Springer Journals
Copyright
Copyright © The Author(s) 2021
ISSN
2190-5487
eISSN
2190-5495
DOI
10.1007/s13201-021-01493-3
Publisher site
See Article on Publisher Site

Abstract

The facile synthesis of graphene wool doped with oleylamine-capped silver nanoparticles (GW-αAgNP) was achieved in this study. The effect of concentration, pH, temperature and natural organic matter (NOM) on the adsorption of a human carcinogen (benzo(a)pyrene, BaP) was evaluated using the doped graphene wool adsorbent. Furthermore, the antibacterial potential of GW-αAgNP against selected drug-resistant Gram-negative and Gram-positive bacteria strains was evaluated. Isotherm data revealed that adsorption of BaP by GW-αAgNP was best described by a multilayer adsorption mechanism predicted by Freundlich model with least ERRSQ < 0.79. The doping of graphene wool with hydrophobic AgNPs coated with functional moieties significantly increased the maximum adsorption capacity of GW-αAgNP over GW based on the q and q predicted by Langmuir and Sips models. π-π interactions contributed to sorbent-sorbate interaction, due to the max m presence of delocalized electrons. GW-αAgNP-BaP interaction is a spontaneous exothermic process (negative ΔH and ΔG) , with better removal efficiency in the absence of natural organic matter (NOM). While GW is more feasible with higher maximum adsorption capacity (q ) at elevated temperatures, GW-αAgNP adsorption capacity and efficiency is best at ambi- ent temperature, in the absence of natural organic matter (NOM), and preferable in terms of energy demands and process economics. GW-αAgNP significantly inhibited the growth of Gram-negative Pseudomonas aeruginosa and Gram-positive Bacillus subtilis strains, at 1000 mg/L dosage in preliminary tests, which provides the rationale for future evaluation of this hybrid material as a smart solution to chemical and microbiological water pollution. Keywords Adsorption · Antimicrobial property · Graphene wool composite · Silver nanoparticles · Water treatment Introduction environment and poses health risk due to its recalcitrance to biodegradation (Yerushalmi et al. 2006). The maximum Benzo(a)pyrene (BaP) is regarded as one of the most haz- acceptable concentration (MAC) of PAHs in surface water is ardous environmental pollutants exhibiting both genotoxic 0.01 µg/L; however, several reports suggest that BaP levels and carcinogenic toxicity in humans according to the Inter- detected in South Africa are higher than the MAC value, national Agency for Research on Cancer (IARC) (IARC thus posing a potential health risk (Adeniji et al. 2019). 2010; Hardonnière et al. 2016). BaP belongs to the group Furthermore, the adaptive resistance of several bacteria of ubiquitous emerging chemical pollutants (ECPs) known to antibiotics, such as chloramphenicol, penicillin, etc., has as polycyclic aromatic hydrocarbons (PAHs) (Adeola & led to the interesting discovery that silver nanoparticles can Forbes 2020; Munyeza et al. 2020). BaP is persistent in the inhibit microbial growth and may be lethal against drug- resistant bacteria (Anthony et  al. 2014; McBirney et  al. 2016; Huang et al. 2017). Advances in research into a hybrid * Patricia B. C. Forbes approach to environmental protection and remediation have patricia.forbes@up.ac.za brought about the need for the development of “smart” materials/composites with multifunctional capabilities for Department of Chemistry, Faculty of Natural and Agricultural Sciences, University of Pretoria, Lynnwood improved efficiency and process economics (Bezza and Road, Hatfield, Pretoria 0002, South Africa Chirwa 2016; Miren et al. 2018; Adeola & Forbes 2021b). Water Utilisation and Environmental Engineering Division, Several materials with antimicrobial properties have been Department of Chemical Engineering, University of Pretoria, developed for the removal of pollutants in aqueous matrices, Lynnwood Road, Hatfield, Pretoria 0002, South Africa Vol.:(0123456789) 1 3 172 Page 2 of 15 Applied Water Science (2021) 11:172 examples of such materials are polyanilineTi(IV)arseno- calcium chloride (CaCl ) were purchased from Associated phosphate (Bushra et al. 2014), iron and manganese coated Chemical Enterprises (ACE, Johannesburg, South Africa). silica gel (Ahmad et al. 2015), chitosan doped with silver 9–30  μm coarse quartz wool (Arcos Organics, New Jer- nanoparticles (Ishihara et al. 2015), nano-silver-supported sey, USA), argon, and hydrogen (99.999%, Afrox, South activated carbon (Eltugral et al. 2016), graphene foam/TiO Africa) were purchased for GW synthesis. Sterile syringe nanosheet hybrids (Wang et al. 2017), iron nanoparticles filters (33 mm diameter) with a 0.22 µm pore size contain- (Da’na et al. 2018), silk fiber doped with tannic acid (Zhang ing a hydrophilic polyethersulfone (PES) membrane were et al. 2019), antimicrobial polymer (Li et al. 2020) chitosan/ purchased from Merck (Darmstadt, Germany). The anti- nitrogen-doped graphene quantum dots (Amari et al. 2021), bacterial tests were carried out using model Gram-negative etc. The design of composites has reportedly enhanced phys- Pseudomonas aeruginosa CB1 and Gram-positive Bacil- icochemical properties of adsorbents such as specific sur - lus subtilis CN2 bacterial strains that had been previously face area, stability, conductivity, tensile strength, chemical isolated and deposited in the GenBank database under the robustness, charge mobility, flexibility, thin-film thickness, accession numbers KP793922 and KP7939228, respectively and provided a basis for the growing interest in the utiliza- (Bezza and Chirwa 2016). All the solutions were prepared tion of composites for water treatment applications (Adeola with de-ionized water (DI, 9.2 µS/cm ) obtained from a & Forbes 2021b). Milli-Q water purification system (Millipore, Bedford, MA, A comprehensive risk-based assessment of graphene- USA). based composites is currently unavailable; however, it is assumed that the composites may not pose a significant Facile synthesis of GW‑αAgNPs health risk based on their composition, but their lightweight nature may pose inhalation risks (Schinwald et al. 2012). Graphene wool was synthesized using the chemical vapor Thus, the physical structure of the graphene-based material deposition method on a quartz wool substrate whereby an and the fabrication method is critical. With respect to gra- optimized stream of argon, hydrogen, and methane gas was phene wool doped with oleylamine-capped silver nanoparti- temperature ramped to 1200  °C as previously described cles (GW-αAgNPs), the quartz wool substrate acts as a solid (Adeola & Forbes 2019, 2020; Schoonraad et  al. 2020). support, assisting with immobilization of the graphene and Lipopeptide-coated silver nanoparticles were synthesized in silver nanoparticles. Furthermore, unlike most composites phenyl ether with oleylamine and oleic acid as both reducing generated in the form of flakes and powder, GW-αAgNPs agents and capping agents (Liu et al. 2011; Sha et al. 2011; presents a wool-like form that may be more suitable as a Çınar et al. 2011). packing material for filters and other water polishing tools. The composite was prepared as follows: Briefly, GW The overall aim of this study was to synthesize a compos- (200 mg) and DI water (100 mL) were added into a sealed ite of graphene wool and silver nanoparticles (GW-αAgNPs) bottle (250 mL) and stirred gently for 1 h using a magnetic with antibacterial activity, for the removal of a human car- stirrer, before the addition of the dopant mixture. Ag nano- cinogen, namely benzo(a)pyrene, from polluted water. The particles (300 mg) dispersed in diphenyl ether (100 mL) influence of process variables such as pH, temperature, and were added into the GW solution and stirred for 12 h at room initial concentration of BaP on the sorption mechanism was temperature under argon, to ensure that AgNPs coordinated established for optimum efficiency of the composite. Fur - with graphene wool at the water/diphenyl ether interface. thermore, the antibacterial activity of the composite was The GW–αAgNP composite was rinsed with acetone and tested and is discussed briefly for potential dual application centrifuged at 6000 rpm for 10 min, three times consecu- toward water treatment. tively. The obtained GW–αAgNP composites were then washed with hexane to remove residual oleylamine. The final GW–αAgNP composite was freeze-dried for 48 h. The facile Experimental methods synthesis is illustrated in Scheme 1. Chemicals Characterization of the synthesized adsorbent Neat standard (98% purity) of benzo(a)pyrene (BaP) was The morphology of GW and GW-αAgNPs was examined purchased from Supelco (USA). Sodium azide (NaN ), silver by a combination of techniques including scanning elec- nitrate (AgNO , 99.9%), oleic acid (99%), oleylamine (99%), tron microscopy (SEM), with images obtained from a Zeiss phenyl ether (99%), and Tryptic Soybean Broth (TSB) were Ultra-Plus 55 field emission scanning electron microscope purchased from Sigma-Aldrich (Germany). Nitric acid (FE-SEM), operated at 2.0 kV (Zeiss, Germany). High-res- (HNO ), hydrochloric acid (HCl), sodium chloride (NaCl), olution transmission electron microscopy (TEM) images of sodium hydroxide (NaOH), ethanol (EtOH), hexane, and capped-AgNPs and GW-αAgNPs were taken using a JEOL 1 3 Applied Water Science (2021) 11:172 Page 3 of 15 172 Scheme 1 Illustration of the synthetic route to graphene wool-silver nanoparticles composite JEM 2100F (JOEL Ltd, Tokyo, Japan) operated at 200 kV with initial concentrations of the BaP solutions ranging from and equipped with an energy dispersive X-ray spectrom- 100 µg/L to 500 µg/L. The BaP desorption isotherm was eter (EDS) (OXFORD Link-ISIS-300 Zeiss, Germany). The examined by the addition of 5 mL fresh electrolyte with specific surface area (SSA) of GW was determined using equilibration for 24 h, after decanting the adsorption super- the modified Sears’ method (Sears 1956; Adeola & Forbes natant as previously described (Wang et al. 2008; Adeola 2019). FTIR spectra of GW, capped AgNPs and GW- & Forbes 2021a). Adsorption isotherms of BaP were also αAgNPs were obtained using a Bruker Alpha-T spectrometer performed at varying temperatures of 25, 35, and 45 °C (Bruker Optik GmbH, Ettlingen, Germany). Elemental anal- using a thermostated shaking water bath (Wisebath, Celsius ysis of natural organic matter (NOM) was examined using Scientific, South Africa) to determine adsorption thermody - inductively coupled plasma-optical emission spectrometry namics. The role of solution pH was evaluated by pH adjust- (ICP-OES, Spectro Arcos model, Thermo Fisher Scientific, ment with 0.1 M HCl (Merck, South Africa) or NaOH (ACE, South Africa). The conductivity of the background electro- South Africa) over the pH range from 2 to 12, to elucidate lyte was confirmed using an Orion Star A112 conductivity the pH effect on the removal of BaP from aqueous solution. benchtop meter (Thermo Scientific, South Africa), and pH was monitored using a 780-pH meter (Metrohm Herisau, Quantification Switzerland). After equilibration, centrifugation of the vials was per- Sorption isotherm experiments formed at 6000 rpm for 10 min to recover a clear superna- tant. BaP concentrations were analyzed in triplicate (n = 3) Batch adsorption experiments of BaP onto GW and by fluorescence spectroscopy (Horiba Jobin Yvon Fluoro- GW-αAgNPs were carried out in 40 mL PTFE screw cap max-4 spectrofluorometer). For all fluorescence measure- amber vials (Stargate Scientific, South Africa) at 25 ± 1 °C ments, the excitation and quantification emission wave- in a thermostated shaking water bath (Wisebath, Celsius lengths were at 330 and 464 nm, while the excitation and Scientific, South Africa). Background electrolyte (pH = 7.0) emission slit widths were set at 5 nm. The regression coef- contained 0.01  mol/L CaCl (ACE, South Africa) in DI ficient (R ) of the calibration curve was obtained from work- water with 200 mg/L of sodium azide (Sigma-Aldrich, Ger- ing solutions in the range of 100 µg/L to 500 µg/L of BaP many) as a biocide. The isotherm experiment was conducted and blanks were included for both calibration and sorption 1 3 172 Page 4 of 15 Applied Water Science (2021) 11:172 experiments. The equilibrium concentration (C , µg/L) was of 12.67 ± 3.9 nm were estimated via particle size analy- deduced from the calibration equation. The amount of solute sis using the ImageJ software (Fig. 1b and d). Qualitative adsorbed (q , µg/g) was extrapolated using a mass-balance analysis of GW-αAgNP using EDS confirmed the presence equation (Eq. 1) and removal ec ffi iency was estimated using and relative abundance of silver and carbon (Fig. 1c). FTIR Eq. 2: (Fig. 1e and f) revealed two prominent peaks associated with the sp hybridized C=C backbone of graphene and a broad (C − C )V 0 e 0 peak of Si–O-C of functionalized quartz wool (SiO ) coated q = (1) 2 S −1 with graphene at 775 and 1059  cm , respectively (Adeola −1 & Forbes 2020). Bands at 2921, 2856, 1631, 1450  cm where C (µg/L) is the initial concentration, C (µg/L) is the o e regions arising from C–H, C=O, C–N stretching vibrations equilibrium solute concentration, V is the initial volume (L) were observed in GW-αAgNP, respectively (Fig. 1e). Fig- and S is the mass (g) of the adsorbent. ure 1f revealed that several functional groups enhanced the (C − C ) stability of AgNPs and facilitated coordination with GW 0 e Removal efficiency(%) = × 100 (2) (Jyoti et al. 2016). The bands at 3325, 2921, 2856, 1743, −1 1631, 1450, 1377, 1240, 1043 and 460  cm correspond to N–H, C–H, C–C, C=O, C–N, C=N, and Ag–O stretching, Antibacterial test of GW‑ αAgNPs respectively, indicating the presence of oleylamine/oleic acid as the capping agent of silver nanoparticles (Mojahed et al. Sterilization of all glassware and media was carried out in an 2011; Prakash et al. 2013; Tran & Jeong 2015). autoclave at 121 °C for 15 min. A facile test was conducted of bacteria inhibition of GW-αAgNP against model Gram- Sorption isotherm experiments negative and Gram-positive bacteria strains (Pseudomonas aeruginosa CB1 and Bacillus subtilis CN2) previously iso- Adsorption isotherm models are used to investigate the lated in our laboratory (Bezza et al., 2020). The inocula of P. nature of sorbent-sorbate interactions of adsorption (Wang aeruginosa and B. subtilis were cultured overnight in Tryptic et  al. 2018; Zhang et al. 2019; Adeola & Forbes 2021a). Soybean Broth (TSB) under aerobic conditions at 37 °C. Linear regression and nonlinear isotherm models such as The inhibitory concentration of the composite against vis- Linear (Eq. 3), Freundlich (Eq. 4), Langmuir (Eq. 5), and ible growth of P. aeruginosa and B. subtilis after 24 h of Sips model (Eq. 6) were used to fit adsorption experimental incubation at 37 °C was investigated. Concentrations ranging data. The Error Sum of Squares (ERRSQ) (Eq. 7) was used from 0–1000 mg/L of GW-αAgNP were prepared in steri- to test all models used in this study. lized conical flasks containing 100 mL TSB. Thereafter each flask was inoculated with 10 µL of the cultured inoculum. q = K C (3) e d e Optical density measurements were taken after the incuba- tion period. Experiments were conducted in duplicate and q = K C (4) e F controls containing nutrient broth inoculated with inoculum without the inclusion of GW-αAgNPs. Bacteria concentra- q K C tion was estimated in relation to absorbance/optical den- max L e q = (5) sity at 600 nm (OD ) using a UV/Vis spectrophotometer 1 + K C L e (Shimadzu UV-1800, Labotec, South Africa) and corrected by subtracting the background absorbance of the control ms q K C m s (Anthony et al. 2014; Bezza et al. 2020). q = (6) e ms 1 + K .C Results and discussion (q − q ) (7) e,cal e, exp i=1 Adsorbent characterization where K (mg/g) (L/mg) ) and N (dimensionless) is the Freundlich constant and intensity parameter, an indicator The morphology of the synthesized composite was exam- of site energy heterogeneity; q (mg/g) and K (L/mg) max L ined using SEM and TEM (Fig. 1a and b). The high-resolu- are the Langmuir maximum adsorption capacity and Lang- tion images revealed a heterogeneous surface structure with muir constant associated with solute–surface interaction extensive coverage of GW with AgNPs. The oleylamine- energy, respectively; K (L/mg) and q (mg/g) are Sips s max capped AgNPs were analyzed with TEM prior to conjuga- isotherm model constants and maximum adsorption capac- tion with GW, and spherical particles with a mean diameter ity and ms is Sips isotherm exponent; q is the solid-phase 1 3 Applied Water Science (2021) 11:172 Page 5 of 15 172 Fig. 1 Characterization of GW-αAgNP composite, a SEM image of abundance of constituent element obtained from EDS site mapping), GW-αAgNP (2 µm scale) (inset: TEM image of GW (200 nm scale)), d Particle size distribution of capped AgNPs with estimated diame- b TEM image of oleylamine-capped AgNPs prior to doping experi- ter, e and f FTIR spectra of GW, GW-αAgNP and oleylamine-capped ment (50 nm scale), c EDS spectrum of GW-αAgNP (inset: Relative AgNP concentration (mg/g), C is the liquid phase equilibrium con- irreversibility of the sorption process was calculated for centration (mg/L), and K (L/g) is the sorption distribution doped graphene wool and pristine graphene wool (Table 1). coefficient (Ololade et al. 2018; Adeola & Forbes 2019). Isotherm data for GW-αAgNP adsorption of BaP was best The isotherm regression parameters for Freundlich, Lang- described by a multilayer adsorption mechanism predicted muir, Linear, and Sips model are presented in Table 1 and by the Freundlich model with least ERRSQ < 0.79, while Fig. 2. The hysteresis index (H) which is a measure of the BaP adsorption onto GW was best fitted to the Sips model Table 1 Sorption–desorption Sorption models Adsorption parameters Desorption parameters parameters for adsorption of BaP onto GW-αAgNP and GW GW-αAgNP GW GW-αAgNP GW (desorption hysteresis index K 1.12e3 0.60e2 K 0.55e2 0.21e2 (H) derived from Freundlich f (ads) f (des) isotherm model) Freundlich N 3.13 0.1 N 0.1 0.01 (ads) (des) SSE 0.78 2.50 H-index 31.3 10.0 Langmuir q (µg/g) 13.67e3 0.59e2 max K (L/µg) 2.01e-4 6.67e4 SSE 2.03 1.88 Linear K 2.75 0.93 SSE 1.58 2.45 Sips K 3.36 2.38 q (µg/g) 97.62 59.76 m 9.68 6.05 SSE 2.03 1.87 H: Sorption–desorption hysteresis index, H = N /N ads des 1 3 172 Page 6 of 15 Applied Water Science (2021) 11:172 Fig. 2 Adsorption isotherm model plots for the interaction between sorbate and sorbents a GW and BaP b doped GW-αAgNP and BaP. (Experi- mental conditions: C = 100–500 µg/L; dosage = 5 mg per 5 mL, mixing rate = 200 rpm, T = 25 ± 1 °C, contact time: 24 h) (Langmuir–Freundlich hybrid) with ERRSQ < 1.88, respec- sorbed BaP was three-fold higher in GW-αAgNP than pris- tively (Table 1). These findings are consistent with previ- tine GW, further confirming higher binding strength with ous results obtained from the adsorption of phenanthrene BaP. Pore deformation and alteration of the surface struc- and pyrene onto pristine graphene wool (Adeola & Forbes ture of sorbents via build-up in unrelaxed pore volume also 2019). The doping of graphene wool with hydrophobic cause hysteretic behavior in sorption processes (Nguyen AgNPs coated with organic functional moieties significantly et  al. 2004; Cornelissen et al. 2005). Therefore, the high increased the maximum adsorption capacity of GW-αAgNP hysteretic behavior of GW-αAgNP, which exemplifies better over GW based on the q & q predicted by Langmuir and retention of BaP against recontamination of treated water, max m Sips models, respectively (Table 1). BaP is a hydrophobic maybe due to entrapment of solutes by the collapse of the PAH with a high octanol–water partition coefficient logK GW- αAgNP composite structure due to the adsorption pro- ow of 6.13 (Adeola & Forbes 2020), and several reports suggest cess conditions and agitation. a strong affinity between PAHs and hydrophobic surfaces of adsorbents (Khan et al. 2007; Lamichhane et al. 2016; Comparison of adsorbents reported for benzo(a)pyrene Yakout & Daifullah 2013; Yuan et al. 2018). π-π interac- removal tions between the graphene wool composite and the aro- matic structure of BaP, due to the presence of delocalized Table 2 reveals that graphene wool (GW) and doped gra- electrons, also contributes to the adsorption process (Zhao phene wool (GW-αAgNP) competes favorably with other et al. 2011; Zhang et al. 2013; Yang et al. 2015; Adeola & adsorbents reported in the literature for the removal of Forbes 2019). benzo(a)pyrene from aqueous solutions, with efficiency Furthermore, oleylamine and oleic acid used as capping ˃94%. The maximum adsorption capacity deduced from agents as well as the linker between GW and AgNP are large the Langmuir isotherm model (q ) for GW is lower than max hydrophobic organic molecules that may have improved the some of the adsorbents, however, the adsorption capacity of surface hydrophobicity of the composite. Thus, this may in GW-αAgNPs is higher than activated carbon (AC), biochar turn enhance partitioning (mass transfer) of hydrophobic and granular activated carbon (GAC) for BaP adsorption BaP onto the surface of the composite, leading to enhanced based on available literature. The higher adsorption capacity adsorption capacity (K and q ). The doping of graphene of GW-αAgNP may be due to surface modification associ- d max with oleylamine-capped AgNPs accounts for the compara- ated with the doping experiment; creation of binding sites/ tively high surface and adsorption heterogeneity (N & m ) pores and enhanced hydrophobic sorbate-sorbent interac- index (Table  1). It is evident that adsorption–desorption tions. Oleylamine and oleic acid used as capping agents as interactions between sorbate and sorbents displayed a sig- well as the linker between GW and AgNP are large hydro- nificant degree of hysteresis, as calculated H-index values for phobic organic molecules that may have improved the sur- both sorbates were greater than 1 (N > > > N ) (Table 1) face hydrophobicity of the composite. ads des (Ololade et al. 2018; Adeola & Forbes 2021a). However, Several factors influence the choice of adsorbent for water irreversible entrapment and/or slow rate of desorption of treatment applications, these factors include efficiency, 1 3 Applied Water Science (2021) 11:172 Page 7 of 15 172 Table 2 Comparison of different materials used for removal of benzo(a)pyrene from aqueous solutions Adsorbent Dosage (g/L) Removal effi- Adsorption Reference ciency (%) capacity (mg/g) Wood ash 10.0 > 99 - Pérez-Gregorio et al. (2010) Activated carbon derived from coconut shells 0.5 88 - Amstaetter et al. (2012) Iron oxide nanoparticles (IONPs) 0.13 99 0.029 Hassan et al. (2018) Granular activated carbon (GAC) 50.0 - 2.176 Minkina et al. (2021) Biochar 50.0 - 5.881 Minkina et al. (2021) Activated carbon derived from plastic waste 0.8 85 6.494 IIyas et al. (2021) Graphene wool (GW) 1.0 94.8 0.590 This study GW-αAgNPs 1.0 98.7 13.670 This study non-toxicity, availability of material, flexibility, reusability, etc. (Adeola et al. 2021). However, the wool-like form and porosity of GW-αAgNP, in addition to the potential antibac- terial activity (discussed in Sect. 3.6), are advantages to the use of GW-αAgNP as a packing material for water treatment applications. Eec ff t of initial pH on BaP adsorption The mineral, organic and biotic composition of surface waters depends on the source and geographic location, which in turn affects the water pH and influences the adsorp- tion of chemical pollutants (Kulthanan et al. 2013). Solution pH affects the net charge of the adsorbent and adsorbate, and the alterations are more impactful in compounds and materials with protonated moieties (–OH, –COOH, –NH Fig. 3 Effect of pH on BaP adsorption onto GW-αAgNP (Experi- group, etc.) because they tend to form deprotonated groups/ mental conditions: C = 300  µg/L; dosage = 5  mg per 5  mL, mixing complexes under variable pH conditions (Ahmed & Gas- rate = 200  rpm, T = 25 ± 1  °C, contact time: 24  h). Error bars ± rela- tive standard deviation (RSD), n = 3 ser 2012). In principle, at pH < point of zero charge (PZC), the surface of the adsorbent is positively charged and at pH > PZC, sorbents become negatively charged (Liikanen et  al. 2006; Ololade et al. 2018). The results obtained in Influence of NOM on sorbent‑sorbate interaction this study revealed that the optimum adsorption of BaP by GW-αAgNP occurred under basic pH conditions. This is in Natural organic matter (NOM) is a complex matrix of contrast to GW adsorption of PAHs that was slightly favored organic materials which are present in aquatic environ- under acidic pH (Adeola & Forbes 2019). ments, including drinking water, due to the interconnectiv- Figure 3 reveals that the adsorption is favored to the right ity between the hydrologic cycle, biosphere, and geosphere side of the pH scale due to the nature of the oleylamine- within the ecosystem (Sillanpää et al. 2018). The compo- capped AgNP-GW complex, the surface modification, and sition of NOM is influenced by biogeochemical processes the abundance of hydroxide ions in basic pH that potentially that have occurred within the environment (Myneni 2019). facilitates hydrogen bonding as discussed in Sect. 3.2. Fur- In this study, NOM was isolated from stream sediment col- thermore, excess hydroxide ions at pH > 7 could potentially lected from the University of Pretoria sports campus, South lead to the formation of silver hydroxide, which is hydro- Africa (latitude E28° 14′ 46′′ and longitude S25° 45′ 10′′) phobic and thus enhances the more hydrophobic interac- using established procedures (Ran et  al. 2007; Ololade tions with BaP, which often governs the adsorption and et  al. 2018; Adeola & Forbes 2021a). The mineral phase partitioning of hydrophobic organic compounds (HOC) in was removed from bulk samples via treatment with 1 N HCl water (Vasileva et al. 2009; Apul et al. 2013; Bai et al. 2017; for 45 min at ambient temperature, followed by three con- Adeola & Forbes 2020, 2021b). secutive treatments with 1 N HCl and 10% HN O for 12 h 1 3 172 Page 8 of 15 Applied Water Science (2021) 11:172 experiment (Adeola & Forbes 2021a; Ersan et al. 2016). Fig- ure 5 suggests that significant competitive interactions took place between the NOM, BaP molecules, and the adsorbent leading to the comparative decline in removal efficiency, Freundlich adsorption capacity (K ), partition coefficient (K ), and maximum adsorption capacity (q ). NOM has d max been reported to cause fouling of membranes, and reten- tion of hydrophobic compounds and metals in solution, thus limiting the efficiency of conventional water treatment plants (Mehta et al. 2017; Kurwadkar et al. 2019; Adeola & Forbes 2021b). Essentially, NOM often alters the solution’s chemis- try such as pH, ionic strength, and the presence of leachable trace and heavy metals (Fig. 4), providing a plausible expla- nation for the inhibitory role of NOM (Ersan et al. 2016; Lamichhane et al. 2016; Adeola & Forbes 2021a). Fig. 4 Physicochemical properties and morphology of NOM isolate. Elemental composition was determined using ICP-OES. a Optical Eec ff t of temperature and thermodynamic studies image and b SEM image of NOM (200 nm) Several physicochemical and biological processes are (Gelinas et al. 2001). The residue was washed each time with influenced by temperature. Therefore, the role of tempera - DI water, centrifuged at 6000 rpm for 10 min, decanted, and ture on the adsorption of BaP by pristine GW and doped freeze-dried at − 4 C for 24 h prior to use. Morphological GW-αAgNP was studied at 35, 45, and 55 °C, respectively. and basic characterization of the NOM was carried out as The adsorption data were fit to a linear and Sips isotherm presented in Fig. 4 (see Adeola and Forbes 2021b for more models (Eq. 3 and 6), and it was observed that the maxi- details). The NOM isolate had an irregular, spherical grain mum adsorption capacity (q ) significantly reduced for structure with heterogeneous and porous surface morphol- GW-αAgNP with an increase in temperature, while the ogy (Fig. 4). reverse was observed for GW (Table 3, Fig. 6). The free The effect of NOM on the adsorption of BaP by energy change (ΔG˚), enthalpy (ΔH˚) and entropy (ΔS˚) GW-αAgNP was evaluated using a preloading batch were calculated using the Van’t Hoff plot and equations Fig. 5 Influence of NOM on the removal efficiency and adsorption capacity of benzo(a) pyrene by GW-αAgNP. (Experimental conditions: C = 100—500 µg/L; o (BaP) sorbent dosage = 1 g/L, NOM dosage = 1 g/L, mixing rate = 200 rpm, T = 25 ± 1 °C, contact time: 24 h) Table 3 Thermodynamic parameters for adsorption of BaP onto graphene wool and doped graphene wool Temp. (K) GW GW-αAgNP ΔG˚ (J/mol) ΔH˚ (kJ/mol) ΔS˚ (kJ/mol.K) *q (µg/g) ΔG˚ (J/mol) ΔH˚ (kJ/mol) ΔS˚ (kJ/mol.K) *q (µg/g) m m 298 50.02 59.75 −2507.55 97.62 308 −2560.71 94.42 0.32 63.09 −1636.57 −24.04 −0.07 84.14 318 −6296.06 66.36 −1065.57 76.88 q : maximum adsorption capacity derived from Sips model 1 3 Applied Water Science (2021) 11:172 Page 9 of 15 172 Table 3 revealed positive values of adsorption enthalpy ◦ ◦ ( ΔH ) and entropy (ΔS ), and a negative value of ΔG for GW-BaP interaction, which indicates a spontaneous endo- thermic process as the temperature increased (Ahmed & Gasser 2012). This result is in agreement with a previous study on the adsorption of phenanthrene and pyrene by GW (Adeola & Forbes 2019). In contrast, GW-αAgNP-BaP inter- action is a spontaneous exothermic process (negative ΔH and ΔG), with a reduction in system chaos (negative ΔS ) and adsorption capacity as the temperature is increased. While GW is more efficient at elevated temperatures, doping GW with oleylamine-capped AgNPs improved the adsorp- tion capacity and ensured optimum removal efficiency at ambient temperature, which is better in terms of energy eco- nomics and industrial application. Fig. 6 Van’t Hoff equation for BaP adsorption onto GW and Antibacterial activity of GW‑αAgNP GW-αAgNP from aqueous solution Silver nanoparticles and composites have attracted scientific (eqs. 8 and 9) (Fig. 6), in order to elucidate the thermody- attention due to the continuous upsurge of drug-resistant namic nature of adsorption of BaP as a function of temper- bacteria (Bezza et al. 2020; Cobos et al. 2020). Bacterial ature (Yakout & Daifullah 2013; Adeola & Forbes 2019). strains are classified as Gram-positive (G + ve) or Gram- negative (G-ve) based on film assemblage with layers of ◦ ◦ ΔS ΔH lnK = − (8) peptidoglycan (PG) (Proft and Baker 2009). G − ve microbes R RT have a thin PG (1–5 nm) between the cytoplasmic film and external layer, while G + ve microbes have a thicker PG ◦ ◦ ◦ ΔG =ΔH − TΔS (9) layer (~ 30 nm) without an external film (Kim et al. 2007). The mechanism of action of silver-containing materials is where ΔG is the change in the Gibbs free energy (cal/mol); described in Fig. 7. Silver damages the cytoplasmic mem- ΔH is the change in enthalpy (cal/mol), and ΔS is the change brane of microbes, creates oxidative stress with the cells, in entropy (kJ/mol.K), R = gas constant (8.314 J/mol.K), damages DNA, denatures cell proteins and has a lethal T = thermodynamic temperature (K) and K is adsorption effect on microorganisms, including drug-resistant bacteria capacity determined from the linear isotherm model. (Ahmad et al. 2020). Fig. 7 A plausible mechanism for the antimicrobial action of silver nanoparticles. (Repro- duced with permission from Ahmad et al. Copyright 2020, Elsevier) 1 3 172 Page 10 of 15 Applied Water Science (2021) 11:172 Several studies have established the antibacterial action contamination in aqueous media has gained vast attention of AgNPs and composites, with different minimum inhibi- (Liu et al. 2011; Loan Khanh et al. 2019; Bezza et al. 2020). tory concentrations against some drug-resistant microbes The antibacterial activity of GW-αAgNPs and pristine (Table  4). The minimum inhibitory concentration (MIC) AgNPs was tested against the Gram-negative Pseudomonas is regarded as the lowest concentration of an antimicrobial aeruginosa CB1 and Gram-positive Bacillus subtilis CN2 agent that inhibits the growth of microbes, recorded in mg/L strains by the standard micro-dilution method. Earlier or μg/mL (Cobos et al. 2020). The literature suggests that reports suggest that P. aeruginosa and B. subtilis strains are AgNPs and bimetallic nanocomposites (such as Au–Ag, capable of adaptive resistance to antibiotics such as penicil- Fe-Ag) are more effective against microorganisms based on lin and tetracycline (Araya et al. 2019; Pang et al. 2019). MIC values; however, the potential adverse effects of AgNPs Figure 8 reveals a dose-dependent reduction in the concen- on human health have been a major concern, hence research tration of Gram-negative Pseudomonas aeruginosa CB1 into stabilizing AgNPs using capping agents and entrap- and Gram-positive Bacillus subtilis CN2 strains after 24 h ment within a bulky substrate to limit its release potential/ incubation period as a decrease in turbidity was recorded Table 4 A brief summary of silver-containing composites and microorganisms inhibited along with their minimum inhibitory concentrations (MIC) as reported in the literature (mg/L) Composite Microbes Minimum inhibitory References concentration (mg/L) AgNPs/starch/sodium alginate/lemon- Escherichia coli Not reported Maizura et al. (2007) grass oil a a b Sodium Alginate/AgNPs Staphylococcus aureus, 80, 40 Mohammed Fayaz et al. (2009) Escherichia coli a a b c d Silver nanocomposites Staphylococcus aureus, 250, 62.5, 125, 2000 Egger et al. (2009) Escherichia coli, Candida albicans, Aspergillus niger a a b c Bimetallic Au@Ag core–shell nanopar- Escherichia coli, 1.56, 1.88, 2.5 Banerjee et al. (2011) ticles Pseudomonas aeruginosa, Enterococcus faecalis AgNP-Bovin serum albumin (BSA) Staphylococcus aureus, 469.2 Espinosa-Cristóbal et al. (2015) Escherichia coli, Enterococcus faecalis Polycaprolactone-silver composites Escherichia coli, Staphylococcus aureus, 12.5 Pazos-Ortiz et al. (2017) (PCL-AgNPs) Pseudomonas aeruginosa a b a b c Ag-microfibrillated cellulose biocom- Escherichia coli, Staphylococcus 125, 1500, 125 Garza-Cervantes et al. (2020) posite aureus, Pseudomonas aeruginosa Chitosan-AgNP Staphylococcus aureus 32.98 Quintero-Quiroz et al. (2020) a a,b c d Ag–Fe bimetallic nanoparticles Staphylococcus aureus, 125, 62.5, 31.23 Padilla-Cruz et al. (2021) Escherichia coli, Candida albicans, Pseudomonas aeruginosa Graphene oxide-AgNP Staphylococcus aureus, Not reported Jaworski et al. (2018) b b,d a,c Escherichia coli, 64, 32 Cobos et al. (2020) Candida albicans, Pseudomonas aeruginosa AgNP Staphylococcus aureus, < 8.0 Gurunathan (2019); Loo et al. Escherichia coli, 10–12 (2018) c abc d Candida albicans, 125, 62.5 Dong et al. (2019); Vazquez- Pseudomonas aeruginosa Muñoz et al. (2019) Padilla-Cruz et al. (2021) Gelatin-stabilized AgNPs and curcumin Staphylococcus aureus, Pseudomonas 125 Loan Khanh et al. (2019) aeruginosa Lipopetide-capped AgNP Pseudomonas aeruginosa, 15.63 Bezza et al. (2020) Bacillus subtillis Graphene wool doped with oleylamine- Pseudomonas aeruginosa, 1000 This study capped AgNPs Bacillus subtillis 1 3 Applied Water Science (2021) 11:172 Page 11 of 15 172 Fig. 8 Visible antibacterial activity of composites a 500 and determined spectrophotometrically at an optical density of 600  nm 1000  mg/L of GW-αAgNP in 100  mL TSB nutrient medium inocu- (OD ), n = 2. (100  mL TSB nutrient medium inoculated with P. 600nm lated with P. aeruginosa (left) and B. subtilis (right) b 1000 mg/L of aeruginosa and B. subtilis without GW or GW-αAgNP were included GW in 100 mL TSB nutrient medium inoculated with P. aeruginosa as controls) and B. subtilis c Variation in concentration of respective bacteria spectrophotometrically at an optical density of 600 nm. The adsorptive properties of GW-αAgNP suggest that the mate- decline in turbidity is a function of bacteriostatic/bacteri- rial may be suitable for the fabrication of adsorbent layer(s) cidal activity of the composite, relative to control experi- in water filtration or purification devices. ments. The reduction is most significant at 1000  mg/L (GW-αAgNP) and was more visible in doped GW than pristine GW. Factors such as particle size, stabilizing agent, Conclusion composition of culture media and bacteria type, inoculum size, and leachability of silver ions from the composite, play Facile synthesis of GW doped with oleylamine-capped a critical role in determining the MIC values. Optical density AgNPs was achieved in this study. The effect of concen- measurement is the most common technique for determining tration, pH, and temperature on the adsorption of benzo(a) bacteria concentration and efficacy of antibacterial agents pyrene, a human carcinogen, was evaluated using the doped (McBirney et al. 2016; Huang et al. 2017). The agar disk graphene wool. Isotherm data suggest that GW-αAgNP-BaP diffusion test is another method often used for nanoparti- interaction is a spontaneous exothermic process (negative cles that are dispersible in water to form a uniform solu- ΔH and ΔG), characterized by a decline in system chaos tion, however, due to the macroscopic and fibrous nature (negative ΔS ) and adsorption capacity as temperature of GW, it was impossible to obtain a uniform dispersion of increases. This study suggests that the adsorption capac- the material in the solution. When such experiments were ity of GW improved and will be more efficient at ambient attempted, the release and mobility of silver ions from the temperature ( ΔG and q ), when doped with AgNPs as a max macrostructure through the semi-solid agar were signifi - result of improved surface hydrophobicity and heterogene- cantly limited, thus constricting the inhibition zone to the ity, leading to the creation of more binding sites for BaP to site of deposition on the plate (Fig. 9), a similar finding was adhere to. Results revealed a high degree of desorption hys- reported for large-sized AgNPs (Xiu et al. 2012; Bezza et al. teresis and irreversible sorption, suggesting a strong binding 2020). However, the texture, fibrous nature, antibacterial and strength between the doped GW and pollutant, thus limiting 1 3 172 Page 12 of 15 Applied Water Science (2021) 11:172 Fig. 9 Agar disk diffusion test a Before incubation- 100 mg of GW-αAgNP was placed on agar disk with growth medium and Bacillus subtilis culture spread over uniformly, b After 24 h incubation- visible growth of the bacteria around GW-αAgNP with inhibition zone limited to the site of deposition Open Access This article is licensed under a Creative Commons Attri- the ease of recontamination. Results also show that the pres- bution 4.0 International License, which permits use, sharing, adapta- ence of NOM in the aqueous matrix is undesirable for the tion, distribution and reproduction in any medium or format, as long application of the synthesized adsorbent due to competitive as you give appropriate credit to the original author(s) and the source, adsorption. Several studies have established the cytoplas- provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are mic toxicity and antimicrobial properties of silver-contain- included in the article's Creative Commons licence, unless indicated ing nanomaterials and in this study, preliminary results also otherwise in a credit line to the material. If material is not included in revealed that there was a dose-dependent reduction in the the article's Creative Commons licence and your intended use is not concentration of Gram-negative Pseudomonas aeruginosa permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a CB1 and Gram-positive Bacillus subtilis CN2 strains tested copy of this licence, visit http://cr eativ ecommons. or g/licen ses/ b y/4.0/ . in the presence of GW-αAgNP. Furthermore, unlike most composites that are generated in the form of flakes or powder, GW-αAgNP provides a wool-like form that may be more suitable as a packing mate- References rial for filters and other water polishing tools due to its light- Adeniji AO, Okoh OO, Okoh AI (2019) Levels of Polycyclic aromatic weight and porous nature. The synthesis of graphene wool is hydrocarbons in the water and sediment of buffalo river estuary, facile and eco-friendly without extensive use of chemicals. south africa and their health risk assessment. Arch Environ Con- Therefore, under appropriate operating conditions, the gra- tam Toxicol 76(4):657–669 phene-based composite can potentially be utilized as a water Adeola AO, Forbes PBC (2019) Optimization of the sorption of selected polycyclic aromatic hydrocarbons by regenerable gra- polishing tool for the removal of emerging organic chemical phene wool. Water Sci Technol 80:1931–1943 pollutants. With further studies and suitable fabrication, this Adeola AO, Forbes PBC (2020) Assessment of reusable graphene hybrid material has the potential to serve as a smart solution wool adsorbent for the simultaneous removal of selected 2–6 to chemical and microbial pollution in water. ringed polycyclic aromatic hydrocarbons from aqueous solu- tion. Environ Technol. https://doi. or g/10. 1080/ 09593 330. 2020. 18240 24 Acknowledgements Authors acknowledge the assistance provided by Adeola AO, Forbes PBC (2021a) Influence of natural organic matter Dr F. A. Bezza during the antibacterial testing of the composite, the fractions on PAH sorption by stream sediments and a synthetic University of Pretoria Commonwealth Doctoral Scholarship funding graphene wool adsorbent. Environ Technol Innov 21:101202 (AA) and the Rand Water Professorial Chair program (PF and EC) for Adeola AO, Forbes PBC (2021b) Advances in water treatment tech- providing funding for the research. nologies for removal of polycyclic aromatic hydrocarbons: existing concepts, emerging trends, and future prospects. Water Funding This study is supported by University of Pretoria Common- Environ Res 93:343–395 wealth Doctoral Scholarship funding (AA) and the Rand Water Profes- Ahmad HB, Yasmin GE, Arain SA, Bhatti IA, Hussain M (2015) sorial Chair program (PF and EC). Synthesis of some novel adsorbents for antimicrobial activity and removal of arsenic from drinking water. Korean J Chem Declarations Eng 32:661–666 Ahmad SA, Sachi Das S, Khatoon A, Tahir Ansari M, Afzal M, Saquib Hasnain M, Kumar Nayak A (2020) Bactericidal activity Conflict of interest The authors declare that there is no conflict of in- of silver nanoparticles: a mechanistic review. Mater Sci Energy terest. Technologies 3:756–769 Ahmed IM, Gasser MS (2012) Adsorption study of anionic reac- Ethical approval This article does not contain any studies with human tive dye from aqueous solution to Mg-Fe-CO layered double participants or animals performed by any of the authors. hydroxide (LDH). Appl Surf Sci 259:650–656 1 3 Applied Water Science (2021) 11:172 Page 13 of 15 172 Amari A, Elboughdiri N, Ghernaout D, Lajimi RH, Alshahrani AM, Ersan G, Kaya Y, Apul OG, Karanfil T (2016) Adsorption of organic Tahoon MA, Rebah FB (2021) Multifunctional crosslinked contaminants by graphene nanosheets, carbon nanotubes and chitosan/nitrogen-doped graphene quantum dot for wastewater granular activated carbons under natural organic matter preload- treatment. Ain Shams Eng J. https://doi. or g/10. 1016/j. asej. 2021. ing conditions. Sci Total Environ 565:811–817 02. 024 Espinosa-Cristóbal LF, Martínez-Castañón GA, Loyola-Rodríguez JP, Amstaetter K, Eek E, Cornelissen G (2012) Sorption of PAHs and Niño-Martínez N, Ruiz F, Zavala-Alonso NV, Lara RH, Reyes- PCBs to activated carbon: coal versus biomass-based quality. López SY (2015) Bovine serum albumin and chitosan coated sil- Chemosphere 87:573–578 ver nanoparticles and its antimicrobial activity against oral and Anthony KJP, Murugan M, Gurunathan S (2014) Biosynthesis of nonoral bacteria. J Nanomater, 420853 silver nanoparticles from the culture supernatant of Bacillus Fayaz AM, Balaji K, Girilal M, Kalaichelvan PT, Venkatesan R (2009) marisflavi and their potential antibacterial activity. J Ind Eng Mycobased synthesis of silver nanoparticles and their incorpora- Chem 20:1505–1510 tion into sodium alginate films for vegetable and fruit preserva- Apul OG, Wang Q, Zhou Y, Karanfil T (2013) Adsorption of aromatic tion. J Agric Food Chem 57:6246–6252 organic contaminants by graphene nanosheets: comparison with Garza-Cervantes JA, Mendiola-Garza G, de Melo EM, Dugmore TIJ, carbon nanotubes and activated carbon. Water Res 47:1648–1654 Matharu AS, Morones-Ramirez JR (2020) Antimicrobial activity Araya G, Benites J, Reyes JS, Marcoleta AE, Valderrama JA, Lagos of a silver-microfibrillated cellulose biocomposite against suscep- R, Monasterio O (2019) Inhibition of Escherichia coli and tible and resistant bacteria. Sci Rep 10:7281 Bacillus subtilis FtsZ Polymerization and Bacillus subtilis Gelinas Y, Prentice KM, Baldock JA, Hedges J (2001) An improved Growth by Dihydroxynaphtyl Aryl Ketones. Front Microbiol thermal oxidation method for the quantification of soot/graphite 10:1225. https:// doi. org/ 10. 3389/ fmicb. 2019. 01225 carbon in sediments and soils. Environ Sci Technol 21:3519–3525 Bai H, Zhou J, Zhang H, Tang G (2017) Enhanced adsorbability and Gurunathan S (2019) Rapid biological synthesis of silver nanoparti- photocatalytic activity of TiO -graphene composite for polycy- cles and their enhanced antibacterial effects against Escherichia clic aromatic hydrocarbons removal in aqueous phase. Colloids fergusonii and Streptococcus mutans. Arab J Chem 12:168–180 Surf, B 150:68–77 Hardonnière K, Saunier E, Lemarié A, Fernier M, Gallais I, Héliès- Banerjee M, Sharma S, Chattopadhyay A, Ghosh SS (2011) Enhanced Toussaint C, Mograbi B, Antonio S, Bénit P, Rustin P, Janin M, antibacterial activity of bimetallic gold-silver core-shell nanopar- Habarou F, Ottolenghi C, Lavault M-T, Benelli C, Sergent O, Huc ticles at low silver concentration. Nanoscale 3:5120–5125 L, Bortoli S, Lagadic-Gossmann D (2016) The environmental car- Bezza FA, Chirwa EMN (2016) Biosurfactant-enhanced bioremedia- cinogen benzo[a]pyrene induces a Warburg-like metabolic repro- tion of aged polycyclic aromatic hydrocarbons (PAHs) in creosote gramming dependent on NHE1 and associated with cell survival. contaminated soil. Chemosphere 144:635–644 Sci Rep 6:30776 Bezza FA, Tichapondwa SM, Chirwa EMN (2020) Synthesis of bio- Hassan SSM, Abdel-Shafy HI, Mansour MSM (2018) Removal of pyr- surfactant capped silver nanoparticles characterization and their ene and benzo(a)pyrene micropollutant from water via adsorption potential application for bactericidal purposes. J Hazard Mater by green synthesized iron oxide nanoparticles. advances in Natu- 393:122319 ral Sciences. Nanosci Nanotechnol 9(1):015006 Bushra R, Shahadat M, Ahmad A, Nabi SA, Umar K, Oves M, Raeissi Huang W, Wang J-Q, Song H-Y, Zhang Q, Liu G-F (2017) Chemi- AS, Muneer M (2014) Synthesis, characterization, antimicrobial cal analysis and in vitro antimicrobial effects and mechanism of activity and applications of polyanilineTi(IV)arsenophosphate action of Trachyspermum copticum essential oil against Escheri- adsorbent for the analysis of organic and inorganic pollutants. J chia coli. Asian Pac J Trop Med 10:663–669 Hazard Mater 264:481–489 IARC, International Agency for Research on Cancer, (2010) IARC Çınar S, Gündüz G, Mavis B, Çolak U (2011) Synthesis of silver nano- Monographs on the Evaluation of Carcinogenic Risks to Humans. particles by Oleylamine-Oleic acid reduction and its use in mak- (Lyon: World Health Organization) 92, 1–853 ing nanocable by coaxial electrospinning. J Nanosci Nanotechnol Ilyas M, Ahmad W, Khan H (2021) Utilization of activated carbon 11:3669–3679 derived from waste plastic for decontamination of polycyclic Cobos M, De-La-Pinta I, Quindós G, Fernández MJ, Fernández MD aromatic hydrocarbons laden wastewater. Water Sci Technol (2020) Graphene oxide-silver nanoparticle nanohybrids: synthe- 84:609–631 sis, characterization, and antimicrobial properties. Nanomaterials Ishihara M, Nguyen VQ, Mori Y, Nakamura S, Hattori H (2015) 10(2):376 Adsorption of silver nanoparticles onto different surface structures Cornelissen G, Gustafsson Ö, Bucheli TD, Jonker MTO, Koelmans of chitin/chitosan and correlations with antimicrobial activities. AA, van Noort PCM (2005) Extensive sorption of organic com- Int J Mol Sci 16:13973–13988 pounds to black carbon, coal, and kerogen in sediments and soils: Jaworski S, Wierzbicki M, Sawosz E, Jung A, Gielerak G, Biernat J, mechanisms and consequences for distribution, bioaccumulation, Jaremek H, Łojkowski W, Woźniak B, Wojnarowicz J, Stobiński and biodegradation. Environ Sci Technol 39:6881–6895 L, Małolepszy A, Mazurkiewicz-Pawlicka M, Łojkowski M, Dana E, Taha A, Afkar E (2018) Green synthesis of iron nanoparticles Kurantowicz N, Chwalibog A (2018) Graphene oxide-based nano- by acacia nilotica pods extract and its catalytic, adsorption, and composites decorated with silver nanoparticles as an antibacterial antibacterial activities. Appl Sci 8:1922 agent. Nanoscale Res Lett 13:116 Dong Y, Zhu H, Shen Y, Zhang W, Zhang L (2019) Antibacterial activ- Jyoti K, Baunthiyal M, Singh A (2016) Characterization of silver nano- ity of silver nanoparticles of different particle size against Vibrio particles synthesized using Urtica dioica Linn. leaves and their Natriegens. PLOS ONE, 14, e0222322 synergistic effects with antibiotics. J Rad Res Appl Sci 9:217–227 Egger S, Lehmann RP, Height MJ, Loessner MJ, Schuppler M (2009) Khan E, Khaodhir S, Rotwiron P (2007) Polycyclic aromatic hydrocar- Antimicrobial properties of a novel silver-silica nanocomposite bon removal from water by natural fiber sorption. Water Environ material. Appl Environ Microbiol 75:2973 Res 79:901–911 Eltugral N, Simsir H, Karagoz S (2016) Preparation of nano-silver- Kim JS, Kuk E, Yu KN, Kim J-H, Park SJ, Lee HJ, Kim SH, Park YK, supported activated carbon using different ligands. Res Chem Park YH, Hwang C-Y, Kim Y-K, Lee Y-S, Jeong DH, Cho M-H Intermed 42:1663–1676 (2007) Antimicrobial effects of silver nanoparticles. Nanomed Nanotechnol Biol Med 3:95–101 1 3 172 Page 14 of 15 Applied Water Science (2021) 11:172 Kulthanan K, Nuchkull P, Varothai S (2013) The pH of water from matter towards adsorption and desorption of phenol and its chlo- various sources: an overview for recommendation for patients rinated derivatives. J Environ Chem Eng 6:3485–3494 with atopic dermatitis. Asia Pac Allergy 3:155–160 Padilla-Cruz AL, Garza-Cervantes JA, Vasto-Anzaldo XG, García- Kurwadkar S, Hoang TV, Malwade K, Kanel SR, Harper WF, Struck- Rivas G, León-Buitimea A, Morones-Ramírez JR (2021) Syn- hoff G (2019) Application of carbon nanotubes for removal of thesis and design of Ag–Fe bimetallic nanoparticles as antimicro- emerging contaminants of concern in engineered water and waste- bial synergistic combination therapies against clinically relevant water treatment systems. Nanotechnol Environ Eng 4(1):1–16 pathogens. Sci Rep 11:5351 Lamichhane S, Bal Krishna KC, Sarukkalige R (2016) Polycyclic Pang Z, Raudonis R, Glick BR, Lin T-J, Cheng Z (2019) Antibiotic aromatic hydrocarbons (PAHs) removal by sorption: A review. resistance in Pseudomonas aeruginosa: mechanisms and alterna- Chemosphere 148:336–353 tive therapeutic strategies. Biotechnol Adv 37:177–192 Li H, He N, Cheng C, Dong H, Wen J, Wang X (2020) Antimicrobial Pazos-Ortiz E, Roque-Ruiz JH, Hinojos-Márquez EA, López-Esparza polymer contained adsorbent a promising candidate with remark- J, Donohué-Cornejo A, Cuevas-González JC, Espinosa-Cristóbal able anti-biofouling ability and durability for enhanced uranium LF, Reyes-López SY (2017) Dose-dependent antimicrobial activ- extraction from seawater. Chem Eng J 388:124273 ity of silver nanoparticles on polycaprolactone fibers against Liikanen R, Yli-Kuivila J, Tenhunen J, Laukkanen R (2006) Cost and gram-positive and gram-negative bacteria. J Nanomater. https:// environmental impact of nanofiltration in treating chemically pre-doi. org/ 10. 1155/ 2017/ 47523 14 treated surface water. Desalination 201:58–70 Pérez-Gregorio MR, García-Falcón MS, Martínez-Carballo E, Simal- Liu L, Liu J, Wang Y, Yan X, Sun DD (2011) Facile synthesis of Gándara J (2010) Removal of polycyclic aromatic hydrocar- monodispersed silver nanoparticles on graphene oxide sheets with bons from organic solvents by ashes wastes. J Hazard Mater enhanced antibacterial activity. New J Chem 35:1418–1423 178:273–281 Loan Khanh L, Thanh Truc N, Tan Dat N, Thi Phuong NN, van Toi V, Prakash P, Gnanaprakasam P, Emmanuel R, Arokiyaraj S, Saravanan M Thi Thu HN, Ngoc Quyen T, Thi Thanh LT, Thi Hiep N (2019) (2013) Green synthesis of silver nanoparticles from leaf extract of Gelatin-capped composites of silver nanoparticles and curcumin: Mimusops elengi, Linn. for enhanced antibacterial activity against characterization, antibacterial and antioxidant study. Sci Technol multi drug resistant clinical isolates. Colloids Surf B 108:255–259 Adv Mater 20:276–290 Proft T, Baker EN (2009) Pili in Gram-negative and Gram-positive Loo YY, Rukayadi Y, Nor-Khaizura M-A-R, Kuan CH, Chieng BW, bacteria—structure, assembly and their role in disease. Cell Mol Nishibuchi M, Radu S (2018) In vitro antimicrobial activity of Life Sci 66:613. https:// doi. org/ 10. 1007/ s00018- 008- 8477-4 green synthesized silver nanoparticles against selected gram- Quintero-Quiroz C, Botero LE, Zárate-Triviño D, Acevedo-Yepes N, negative foodborne pathogens. Front Microbiol. https:// doi. org/ Escobar JS, Pérez VZ, Cruz Riano LJ (2020) Synthesis and char- 10. 3389/ fmicb. 2018. 01555 acterization of a silver nanoparticle-containing polymer compos- Maizura M, Fazilah A, Norziah MH, Karim AA (2007) Antibacterial ite with antimicrobial abilities for application in prosthetic and activity and mechanical properties of partially hydrolyzed sago orthotic devices. Biomater Res 24:13 starch-alginate edible film containing lemongrass oil. J Food Sci Ran Y, Sun K, Ma X, Wang GH, Grathwohl P, Zeng EY (2007) Effect 72:C324–C330 of condensed organic matters on solvent extraction and aqueous McBirney SE, Trinh K, Wong-Beringer A, Armani AM (2016) Wave- leaching of PAHs based in soils and sediments. J Environ Poll length-normalized spectroscopic analysis of Staphylococcus 43:111–123 aureus and Pseudomonas aeruginosa growth rates. Biomed Opt Schinwald A, Murphy FA, Jones A, MacNee W, Donaldson K (2012) Express 7:4034–4042 Graphene-based nanoplatelets: a new risk to the respiratory sys- Mehta R, Saha NK, Bhattacharya A (2017) Pretreatment of agriculture tem as a consequence of their unusual aerodynamic properties. e fi ld water for improving membrane u fl x during pesticide removal. ACS Nano 6:736–746 Appl Water Sci 7:3281–3290 Schoonraad G, Madito MJ, Manyala N, Forbes PBC (2020) Syn- Minkina T, Vasilyeva G, Popileshko Y, Bauer T, Sushkova S, thesis and optimisation of a novel graphene wool material by Fedorenko A, Antonenko E, Pinskii D, Mazarji M, Ferreira atmospheric pressure chemical vapour deposition. J Mater Sci CSS (2021) Sorption of benzo[a]pyrene by Chernozem and 55:545–564 carbonaceous sorbents: comparison of kinetics and interaction Sears GW (1956) Determination of specific surface area of colloidal sil- mechanisms. Environ Geochem Health. https:// doi. org/ 10. 1007/ ica by titration with sodium hydroxide. Anal Chem 28:1981–1983 s10653- 021- 00945-8 Sha L, Guanying C, Paras NP, Mark TS (2011) Synthesis of Monodis- Miren J, Aurora M-B, Ulrich K, Tomas G-A (2018) Smart and multi- perse Au, Ag, and AuAg alloy nanoparticleswith tunable size and functional materials and their possible application in façade sys- surface plasmon resonance frequency. Chem Mater 23:4098–4101 tems. J Facade Des Eng 6:19–33 Sillanpää M, Ncibi MC, Matilainen A (2018) Advanced oxidation Mojahed F, Dehghanpour S, Alizadeh M, Mahmoudi A (2011) Wet processes for the removal of natural organic matter from drink- chemical synthesis of oleylamine-capped silver nanoparticles by a ing water sources: a comprehensive review. J Environ Manage fast and facile reproducible method. Synth React Inorg, Met-Org, 208:56–76 Nano-Met Chem 41:664–670 Tran M-H, Jeong HK (2015) Synthesis and characterization of silver Munyeza CF, Osano AM, Maghanga JK, Forbes PBC (2020) Polycyclic nanoparticles doped reduced graphene oxide. Chem Phys Lett aromatic hydrocarbon gaseous emissions from household cooking 630:80–85 devices: a kenyan case study. Environ Toxicol Chem 39:538–547 Vasileva SY, Olenin AY, Romanovskaya GI, Krutyakov YA, Pogonin Myneni SCB (2019) Chemistry of natural organic matter—the next VI, Korotkov AS, Zuev BK (2009) Adsorption preconcentration step: commentary on a humic substances debate. J Environ Qual of pyrene by silver nanoparticles and its determination in aqueous 48:233–235 solutions. J Anal Chem 64:1214–1220 Nguyen TH, Sabbah I, Ball WP (2004) Sorption nonlinearity for Vazquez-Muñoz R, Meza-Villezcas A, Fournier PGJ, Soria-Castro E, organic contaminants with diesel soot: method development and Juarez-Moreno K, Gallego-Hernández AL, Bogdanchikova N, isotherm interpretation. Environ Sci Technol 38:3595–3603 Vazquez-Duhalt R, Huerta-Saquero A (2019) Enhancement of Ololade IA, Adeola AO, Oladoja NA, Ololade OO, Nwaolisa SU, antibiotics antimicrobial activity due to the silver nanoparticles Alabi AB, Ogungbe IV (2018) In-situ modification of soil organic impact on the cell membrane. PLOS ONE, 14, e0224904 1 3 Applied Water Science (2021) 11:172 Page 15 of 15 172 Wang L, Niu J, Yang Z, Shen Z, Wang J (2008) Effects of carbonate and simultaneous ozonation and biotreatment. Water Environ Res and organic matter on sorption and desorption behavior of polycy- 78:2286–2292 clic aromatic hydrocarbons in the sediments from Yangtze River. Yuan P, Li X, Wang W, Liu H, Yan Y, Yang H, Yue Y, Bao X (2018) J Hazard Mater 154:811–817 Tailored design of differently modified mesoporous materials to Wang W, Wang Z, Liu J, Zhang Z, Sun L (2017) Single-step one-pot deeply understand the adsorption mechanism for polycyclic aro- synthesis of graphene foam/TiO2 nanosheet hybrids for effective matic hydrocarbons. Langmuir 34:15708–15718 water treatment. Sci Rep 7:43755 Zhang C, Wu L, Cai D, Zhang C, Wang N, Zhang J, Wu Z (2013) Wang S, Li X, Liu Y, Zhang C, Tan X, Zeng G, Song B, Jiang L Adsorption of polycyclic aromatic hydrocarbons (fluoranthene (2018) Nitrogen-containing amino compounds functionalized and anthracenemethanol) by functional graphene oxide and graphene oxide: Synthesis, characterization and application for removal by ph and temperature-sensitive coagulation. ACS Appl the removal of pollutants from wastewater: a review. J Hazard Mater Interf 5:4783–4790 Mater 342:177–191 Zhang W, Yang Z-Y, Cheng X-W, Tang R-C, Qiao Y-F (2019) Adsorp- Xiu ZM, Zhang QB, Puppala HL, Colvin VL, Alvarez PJ (2012) Negli- tion, antibacterial and antioxidant properties of tannic acid on silk gible particle-specific antibacterial activity of silver nanoparticles. fiber. Polymers 11(6):970 Nano Lett 12:4271–4275 Zhao G, Jiang L, He Y, Li J, Dong H, Wang X, Hu W (2011) Sul- Yakout SM, Daifullah AAM (2013) Removal of selected polycyclic fonated graphene for persistent aromatic pollutant management. aromatic hydrocarbons from aqueous solution onto various adsor- Adv Mater 23:3959–3963 bent materials. Desalin Water Treat 51:6711–6718 Yang K, Chen B, Zhu L (2015) Graphene-coated materials using silica Publisher's Note Springer Nature remains neutral with regard to particles as a framework for highly efficient removal of aromatic jurisdictional claims in published maps and institutional affiliations. pollutants in water. Sci Rep 5:11641 Yerushalmi L, Nefil S, Hausler R, Guiot SR (2006) Removal of pyr - ene and benzo(a)Pyrene from contaminated water by sequential 1 3

Journal

Applied Water Science – Springer Journals

Published: Nov 1, 2021

Keywords: Adsorption; Antimicrobial property; Graphene wool composite; Silver nanoparticles; Water treatment

There are no references for this article.