Surface modification of thin film composite forward osmosis membrane by silver-decorated graphene-oxide nanosheets

Abstract

Forward osmosis (FO), as an emerging technology for seawater desalination and wastewater reuse, has been attracting significant interest because of its energy efficiency. However, membrane fouling represents one of the major limitations for this technology, notably for thin film composite (TFC) polyamide (PA) membranes, which are prone to chlorine attack. In this study, silver nanoparticle (AgNPs)-decorated graphene oxide (GO) nanosheets (as an effective biocidal material) were covalently bonded to the PA surface to impart improved hydrophilicity and antibacterial properties to the membrane. AgNPs were synthesized in situ by the wet chemical reduction of silver nitrate onto the surface of GO nanosheets. The formation of the composite was verified by UV-vis spectroscopy, X-ray diffraction, and transmission electron microscopy techniques. The synthesized GO/Ag nanocomposites were then covalently bonded onto the TFC PA membrane surface using cysteamine through an amide forming condensation reaction.ATR-FTIR and XPS results confirmed the covalent bonding of the nanocomposite onto the TFC PA surface. Overall, the GO/Ag nanocomposite functionalized membranes exhibited super-hydrophilic properties (contact angles below 25°) and significant bacterial (E. coli) inactivation (over 95% in static bacterial inactivation tests) without adversely affecting the membrane transport properties. † Electronic supplementary information (ESI) available: FE-SEM and backscatter electron microscopy of (A) GO functionalized TFC and (B) GO/Ag nanocomposite functionalized TFC. Elements with high atomic numbers backscatter electrons more strongly than lighter elements with low atomic numbers and thus appear brighter on the image (Fig. S1). TEM images of (A) GO, (B) Ag NPs, and (C) GO/ Ag nanocomposite (Fig. S2). ATR-FTIR spectra of (A) a GO nanosheet and GO/Ag nanocomposite and (B) a control TFC and GO/Ag nanocomposite functionalized TFC membrane (Fig. S3). The zeta potential of the surface of the pristine and functionalized membranes as a function of solution pH. Measurements were taken at room temperature (23°C) in a solution of 1 mM KCl by adjusting pH with the dropwise addition of HCl and NaOH (Fig. S4). Surface roughness properties of pristine and GO/Ag functionalized TFC FO membranes (Table S1). XPS results for (A) pristine membrane and (B) cysteamine treated TFC FO membranes. Peaks at 198 eV for Cl2P and 162 for sulfur S2P are shown in (A) and (B), respectively (Fig. S5). Elemental composition of the membrane surface of pristine and functionalized membranes before and after sonication (Table S2). The physical stability of the silver NPs on the Ag NP decorated and GO/Ag functionalized membranes from XPS results. A 7 min bath sonication was applied to the membranes, and the percent of silver on the membrane surface was estimated (Fig. S6). SeeTo address the biofouling problem associated with thin film composite (TFC) forward osmosis (FO) membranes, we have developed novel surface coatings through covalent bonding of silver decorated grap...

Synthesis of Partially Reduced Graphene Oxide/Silver Nanocomposite and Its Inhibitive Action on Pathogenic Fungi Grown Under Ambient Conditions

“…The origin of the 226 nm absorption band belongs to the p-p* transitions of aromatic C=C bond.Whereas the 308 nm shoulder band corresponds to n-p*of C=O bond. [73] The spectrum of rGOÀAg in Figure 8b shows characteristics of both GO as well as Ag. It shows a strong plasma absorption band at 404 nm, which corresponds to Ag Nanoparticles and also shows peak for rGO at 262 nm, originating from p-p* transitions of aromatic C=C bond.…”

The Antibacterial Applications of Graphene and Its Derivatives

“…Compared with membranes containing AgNPs alone, the porous AgGO cellulose membranes provided more opportunities for bacteria to interact with AgNPs . GO‐Ag nanocomposites with the ability to inhibit bacterial growth were used to prevent the formation of biofilms on stainless steel surfaces or thin film composites …”

“…[ 122 ] GO-Ag nanocomposites with the ability to inhibit bacterial growth were used to prevent the formation of biofi lms on stainless steel surfaces or thin fi lm composites. [ 123,124 ] GO sheets with AgNPs have also been used in electrospun nanofi ber mats. GO-Ag was added to the surface of poly (lactide-co-glycolide) (PLGA)-chitosan electrospun mats through covalent bonding by cross-linking 1-ethyl-3-(3′dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) to obtain an antibacterial, scalable, and biodegradable coating material.…”

Novel thin film nanocomposite membranes incorporated with polyoxovanadate nanocluster for high water flux and antibacterial properties

“…It is noteworthy that high fouling tendency, low hydrophilicity and poor performance of FO membranes limited their industrial applications . Typically, most FO membranes have been fabricated using interfacial polymerization (IP) method to construct thin‐film composite (TFC) structures with a selective layer on the top surface of support . Therefore, rationally design of the membranes surface layer with appropriate materials and methods not only enhanced their separation performances but also considered as a promising solution for their limitations from industrial application point of view .…”