Application of silver-tin dioxide composite cathode catalyst for enhancing performance of microbial desalination cell

Abstract

Microbial desalination cell (MDC) is a novel bioelectrochemical system, capable of removing salts and organic matter from wastewater simultaneously. For improving the performance, a carbon supported silver-tin dioxide (Ag-SnO2) composite was synthesized and used as cathode catalyst in a five-chambered MDC (MDC-1). The results were compared with MDC-2 having no catalyst on the cathode. Saline water with a NaCl concentration of 20 g/L was used to evaluate the desalination efficiency of both the MDCs. The electrochemical studies such as cyclic voltammetry and linear sweep voltammetry of the cathode of MDC-1 revealed the superior reduction kinetics. Increased desalination efficiency was observed in MDC-1 (72.6 ± 3.0%) due to presence of Ag-SnO2 catalyst as compared to MDC-2 (57.9 ± 8.6%). Maximum power density of 1.47 W/m3, demonstrated by MDC-1, was noted to be 1.67 times higher than that of MDC-2 (0.88 W/m3). In addition, the coulombic efficiency of MDC-1 was observed to be 14.4 ± 0.2%, which was significantly higher than that observed in MDC-2 (9.5 ± 0.3%). Performance results confirmed the excellent catalytic activity of Ag-SnO2 composite catalyst to be used on the cathode of MDCs, to take forward this cutting-edge technology for field scale application. Keywords: Cathode catalyst, Desalination, Microbial desalination cell, Microbial fuel cell, Oxygen reduction reaction