Abstract
This study aims to compare the effect of silver nanoparticles (AgNPS), graphene oxide (GO), sulfobetaine methacrylate (SBMA), and novel graphene oxide-silver nanoparticle fucntionaziled polysulfobetaine methacrylate (GO-Ag@PSBMA) nanofillers on polyamide (PA) active layer thin film nanocomposite (TFC) forward osmosis (FO) membrane for desalination application. The chemical structure and morphology of the synthesized AgNPs, GO, SBMA (obtained from Sigma-Aldrich), and GO-Ag@PSBMA nanofillers were fully characterized by fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy, Zeta potential, Brunauer-Emmett-Teller (BET), thermos-gravimetric analysis (TGA), and scanning electron microscopy (SEM). Pristine polyamide thin film nanocomposite forward osmosis membranes, AgNPs-incorporated polyamide thin film nanocomposite forward osmosis membranes, GO- incorporated polyamide thin film nanocomposite forward osmosis membranes, SBMA- incorporated polyamide thin film nanocomposite forward osmosis membranes, and GO-Ag@PSBMA-incorporated polyamide thin film nanocomposite forward osmosis membranes were also studied by various characterization techniques including atomic force microscopy( AFM), contact angle (CA), and SEM. Surface SEM images results revealed that the nano-Ag-modified thin film composite membranes (TAg-1, TAg-2, and TAg-3) were composed of highly cross-linked separation layer with entire ridges and valleys, reduced surface roughness, and well-dispersed AgNPs particles. However, at higher concentrations of nano-Ag, AgNPs-modified thin film composite membranes (TAg-4, TAg-5, and TAg-6) exhibited quite high surface roughness compared to pristine thin film composite membrane. Additionally, upon membranes testing, AgNPs-modified thin film composite membranes showed slightly less water permeability and salt rejection capabilities compared with the pristine thin film composite membrane and yet demonstrated superior antifouling properties. Incorporating small amounts ranging from 0 to 1.5 wt.% of graphene oxide into the thin film composite membrane improved the water permeability, rejection, and fouling resistances. Results also indicated that the graphene oxide nanosheets were dispersed well in the polyamide (PA) layer and their addition to the membranes improved their overall performances. With an increasing concentration of graphene oxide from 0 to 1.5 wt.% in the MPD phase during the fabrication, the permeate flux at 1 bar increased from 30.35 to 64.78 L m-2 h-1, while rejections of NaCl, MgCl2 and Na2SO4 slightly decreased when graphene oxide
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concentrations of 1.0 and 1.5 wt% were embedded onto the polyamide active layer. According to the data in this chapter, the prepared SBMA-incorporated thin-film composite membranes presented an improved membrane permeability without compromising salt rejection. When the concentration of SBMA was increased to 1.5 wt%, the water flux increased from 30.35 L m-2 h-1 to 112.6 L m-2 h-1 while NaCl, MgCl2, and Na2SO4 salt rejection were maintained just above ~75 %. Lastly, the SBMA-modified thin film composite membrane's antifouling property was also enhanced, with the flux recovery ratio as high as 88.47 % compared to the pristine thin film composite membrane with a flux recovery ratio of 63.99 %. GO-Ag@PSBMA-incorporated polyamide thin film nanocomposite forward osmosis membranes exhibit higher water flux and reasonable rejection. The GO-Ag@PSBMA-incorporated polyamide thin film nanocomposite forward osmosis membranes also possessed decreased fouling propensity in forward osmosis test than that without embedded GO-Ag@PSBMA nanohybrid.