Quantitative assessment and optimization of bi-functional membrane for remediation of Cr(VI) from wastewater

Abstract

This paper explores the innovative approach of using a green route synthesized cost-effective bi-functional to eliminate toxic hexavalent chromium commonly found in tannery wastewater by using an integrated application of membrane and photocatalyst. Contaminated wastewater is firstly passed through bi-functional ultrafiltration membranes to retain hexavalent chromium and further reducing the toxicity of rejected water having high concentrations of Cr(VI) by photocatalytic reduction into Cr(III) in the presence of sunlight using the same membrane as photocatalyst film. Conditions governing the separation process such as solution pH, nanoparticle loading in polymer matrix, and concentration of Cr(VI) have been optimized to maximize the % rejection and photocatalytic reduction to Cr(III). The purpose of this work was to optimize the process condition through the use of the response surface method (RSM) that governs the process. RSM analysis concludes that excellent rejection of 91.58% and reduction of 87.02% is possible at the predicted pH (5.55), particle loading (2.14%) and Cr(VI) concentration (25 mg/L). HIGHLIGHTS Synergistic approach for Cr(VI) removal by membrane followed by photocatalytic degradation.; Response surface methodology was employed to optimize the parameter governing operation of a bi-functional membrane.; Rejection >90% was achieved using as bi-functional membrane under optimum conditions.; Reduction >85% when used as photocatalysis film.; BET Brunauer–Emmett–Teller results confirm membrane recyclability as it retains its properties after application.;

Keywords

• concentration
• hexavalent chromium
• membrane
• photocatalyst
• reduction
• rejection