Improving the performance of Cr (VI) removal by electrochemical process using microbial cellulose/magnetic nanoparticles electrode

Abstract

This study aimed to improve the performance of the electrochemical (EC) process for hexavalent chromium [Cr (VI)] removal using a metallic polymer anode. In fact, this anode had been prepared via the immobilized Fe3O4 as the magnetic nanoparticles on microbial cellulose (MC). Moreover, MC/Fe3O4 was modified and conducted by polypyrrole (PPy) and a sandwich panel of stainless steel. The conductive MC/Fe3O4 electrode was characterized by XRD, TGA, FE-SEM, and FTIR. In EC process of the Cr (VI) removal using the composite anode, factors such as chromium concentration, pH value, current density, energy consumption, as well as sludge production were also taken into account. The proposed EC reached 99.87% Cr (VI) removal efficiency using the current density of 5.3 mA/cm2 within 20 min, pH of 3 ± 0.5, and 10 mM sodium chloride (NaCl) as the supporting electrolyte. In addition, the composite electrode)SS_MC/Fe3O4@PPY (exhibited lower energy consumption (0.62 kWh/m3), as well as lower sludge production (0.018 kg/m3) compared with other EC processes. Moreover, results of the study revealed that reasons for these phenomena were Cr (VI) adsorption (18% in 30 min) on the composite electrode as well as Cr (VI) reduction on cathode (17% in 30 min). Another reason for the above phenomena could be attributed to EC caused by production of the metallic hydroxide flocks, which was released from stainless steel (90% in 30 min) and magnetic-microbial cellulose (26% in 30 min). Furthermore, MC/Fe3O4@PPy exhibited a good durability in the system. Therefore, the SS_MC/Fe3O4@PPY electrode could be utilized for long periods of time in the process.