In the study, the Ag–SiO 2 –APTES nanocomposite was synthesized via the self-assembly method to prepare Ag–SiO 2 and subsequently used 3-aminopropyltriethoxysilane (APTES) to functionalize its surface. The as-prepared Ag–SiO 2 –APTES nanocomposite was embedded into poly(vinylidene fluoride) (PVDF) membrane by the co-blending way to fabricate the Ag–SiO 2 –APTES membrane. The Ag–SiO 2 –APTES nanocomposites were characterized by X-ray diffraction (XRD). These membrane materials were characterized by field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM) and FT-IR spectra. The performance of membrane was investigated simultaneously for removing the organic dye methylene blue (MB), Rhodamine B, Direct Red 28 and anti-microbial ability. The experimental results demonstrated that the Ag–SiO 2 –APTES modified membrane were presented to be more hydrophilic with a contact angle 55.6 ∘ , whereas the pristine PVDF membrane was 81.8 ∘ . The dye rejection ratios were also improved after adding Ag–SiO 2 –APTES, which reached 86.8% for MB, 87% Rhodamine B, 88% for Direct Red 28, besides, the removal rate of MB was about 98.7% at pH = 11. More importantly, the Ag–SiO 2 –APTES membranes exhibited excellent antifouling properties for treating MB solution and could reach 85% of flux recovery ratio after four cyclic experiment. Finally, via inhibition zone method of antimicrobial test Ag–SiO 2 –APTES membrane exhibited the antimicrobial activity against Escherichia coli ( E. coli ) excellently. The novel antifouling and antibacterial Ag–SiO 2 –APTES membrane has a potential for dye wastewater treatment and water purity.
The superior hydrophilicity of graphene oxide (GO) makes it a promising candidate for improving the permeability and antifouling performance of membranes used for feed water pretreatment in desalination systems . However, the uncontrollable assembly structures of GO laminates on membrane surface restrict the full exertion of its hydrophilicity. In this study, a layer-by-layer self-assembled GO-based nanocomposite membrane with adjustable interlayer spacing and assembly layers was facilely fabricated by alternately depositing GO and (3-Aminopropyl) triethoxyilane modified silicon dioxide (SiO 2 @APTES) on membrane surface via electrostatic interaction. The fully exerted hydrophilicity of GO and well-maintained membrane pore structures facilitated the adsorption and penetration of water molecules, meanwhile, the hydration layer and electronegativity of GO effectively inhibited the adhesion of foulant. Thus, monolayer GO/SiO 2 @APTES/GO endowed P-(G/S/G) 1 membrane with more than 10-fold water flux (560.2 L m −2 h −1 ) than pure PVDF membrane (55.4 L m −2 h −1 ) without sacrificing selectivity ; and the antifouling performance was improved by nearly 50%. Moreover, the nanocomposite membrane presented robust structural stability after physicochemical cleaning. Overall, the nanocomposite membrane affords a novel facile way to fully exert the hydrophilicity of GO to improve permeability and antifouling performance, and is expected to provide an important guarantee for efficient operation of desalination system.
Yali Bai,Zhenhuan Li,Bowen Cheng,Maliang Zhang,Kunmei Su
U–TiO2 is successfully coated with SiO2 and subsequently well modified by APTES, and the core–shell structure exists on TiO2@SiO2 and TiO2@SiO2/APTES, which greatly reduces aggregation of the TiO2 nanoparticles. The photocatalytic activities of U–TiO2, TiO2@SiO2, and TiO2@SiO2/APTES are evaluated using MB decomposition. Nearly 50% of the MB is degraded after 15 min in the presence of the U–TiO2 under UV radiation (300 W), and only 17.44% and 4.18% of the MB is degraded in the presence of the TiO2@SiO2-0.6 and TiO2@SiO2/APTES-1. However, TiO2@SiO2/APTES-0.6 and TiO2@SiO2-0.2 exhibit excellent UV absorbance capacities, and the TiO2@SiO2/APTES-0.6 achieves 80% of the UV-shielding ability of U–TiO2. Poly(p-phenylene sulfide) (PPS) is an easily photodegraded material and TiO2/PPS is more seriously photodegraded than PPS, however, the TiO2@SiO2/APTES nanoparticles can effectively protect the PPS from UV degradation, owing to their lower photocatalytic activities, higher UV-shielding abilities and easy dispersion in the PPS matrix. The breaking strength retention rate of the 1 wt% TiO2@SiO2/APTES/PPS film shows a maximum increase of 38.26%, and the breaking elongation retention rate increased by 41.64% at 2 wt% TiO2@SiO2/APTES loading. These results reveal that the incorporation of the TiO2@SiO2/APTES nanoparticles into the PPS matrix imparts excellent anti-UV properties to the PPS matrix, leading to a mechanical performance improvement.
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