Degradation of organics with simultaneous recovery of silver in a simple visible-light responsive dual photoelectrode photocatalytic fuel cell
An efficient photocatalytic fuel cell system driven by visible-light using BiVO4 photoanode and Cu2O/CuO photocathode has been designed for phenol degradation and the simultaneous silver recovery. Using this system, 86.4% removal of phenol (5 mg/L) and 100% recovery of Ag (40 mg/L) were achieved within 4 h, which was more efficient than that in the individual photocatalytic fuel cell system without Ag+ ions. High Ag+ concentration and low initial pH were beneficial for phenol removal. The surface variations of the photoanode and photocathode were characterized by SEM, XRD and XPS techniques. The Ag species recovered on the photoanode was found to be metallic Ag and Ag2O and the Ag species recovered on the photocathode was determined to be metallic Ag. Ag2O-BiVO4 heterojunction inhibited the recombination of the photo-generated electron-hole pair. Active radicals including h+, •O2- and •OH were determined to be responsible for the degradation of organics by quenching experiments and electron spin resonance analysis. The photo-generated electrons were responsible for the Ag recovery. The proposed system provided an economical and efficient way for the oxidation of organic contaminants and metal ions recovery.