Effect of bio-mediated route synthesized silver nanoparticles for modification of polyethersulfone membranes

This article reports the modification of polyethersulfone (PES) membrane using silver nanoparticles (n-Ag), their characterizations and protein separation performances. As a bio-mediated synthesis route, gram-positive Bacillus subtilis bacterial supernatants were employed for preparing n-Ag. The resulting n-Ag exhibited uniform and well defined spherical morphology with size less than 50 nm. The effect of the incorporation of n-Ag on PES membrane in terms of cross sectional morphology, surface roughness, crystallinity and hydrophilicity were investigated systematically. XPS analysis showed that a significant portion of silver was in silver oxide form. Depth profiling by argon plasma etching and XPS showed the partition of Ag2O and Ag between the membrane surface and the bulk. A minor oxidation on the surface of the silver was observed whereas the internal structure of the membrane retained Ag in its metallic state. The potential of the nano composite membrane for the separation of BSA with varying feed concentration and transmembrane pressure were performed. At 1.5 wt% loading of n-Ag in neat PES, enhancement in bovine serum albumin (BSA) flux and decrease in the rejection were observed. The results and performance of the PES/n-Ag nanocomposite membranes indicate that it would be a deserving candidate for future industrial separations. The experimental results confirm that the incorporation of Ag nanoparticles in PES UF membrane can increase hydrophilicity and reduce the fouling. (C) 2014 Elsevier B.V. All rights reserved.