Recovery of chromium using membrane containing charged material

Abstract

Chromium (Cr) is one of the important materials of metal family with large applications in formation of ferrous alloys viz., steel. Due to its excellent chemical, mechanical and thermal properties it is largely used in mineral, leather tanning, dye, steel, and other alloy industries. Effluents of these industries containing traces of Cr are polluting water bodies and soil in surrounding. It would result in entering in food chain, where it has highly adverse effect on humans, animals, and environment. Hence its recovery from effluent and other streams is highly essential before disposal and exposure to surrounding. The polysulfone (PSF) based membranes were optimized using polyethylene glycol (PEG) as porogen, while ZnO as an additive either treated with or without acid for removal of Cr from water. A reduction in molecular weight of PEG resulted in decrease in water flux indicates reduction in pore size. Further incorporation of ZnO increases the Cr removal. The Cr removal increases further with incorporation of acid treated ZnO. Additionally, HCl treated ZnO showed higher rejection properties, while the effect is not that prominent in HNO3 treated ZnO. This shows the importance of optimization of membrane surface charge for heavy metal removal.