Chitosan-sodium alginate multilayer membrane developed by Fe0@WO3 nanoparticles: Photocatalytic removal of hexavalent chromium.

The WO3 nanostructures were modified by doping with iron and then the polyethersulfone (PES) ultrafiltration (UF) membrane was developed using prepared Fe0-doped WO3 photocatalytic nanoparticles via layer by layer technology. According to UV-vis diffuse reflectance spectroscopy (UV-vis/DRS) characterization, the photocatalytic activity of WO3 nanoparticles could be improved by doping with Fe impurity. The prepared membranes were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX) and contact angle analyzer. The novel photocatalytic membranes were used in removal of hexavalent chromium (Cr(VI)) ions in batch mode as well as filtration system. The novel photocatalytic membranes have shown significant Cr(VI) ions removal under visible-light illumination. By depositing the (CHI-ALG)3.5 bilayers on the PES/UF membrane surface, the Cr(VI) rejection for 5, 25 and 50 mg/l feed concentration were enhanced from 21%, 17% and 9% for neat PES to 56.3%, 41.6% and 30.1% for PES/ (CHI-ALG)3.5 membrane and 99.2%, 92.1% and 78.1% for PES/ (CHI-ALG)3.5/ Fe0@WO3 membrane, respectively.