Electrochemical remediation of BPA in a soil matrix by Pd/Ti and RuO2/Ti electrodes

Abstract

This study aimed to investigate the bisphenol A (BPA) degradation performance of an electrokinetic process coupled with Pd/Ti (PT) and RuO2/Ti (RT) binary metallic oxidation electrodes under a potential gradient of 2 Vcm−1 for 5 days. Fifteen experiments conducted with five processing fluids, namely deionized water (DW), Na2SO4, citric acid (CA), NaOH and NaCl, and two binary metallic oxidation electrodes, Pd/Ti and RT, were investigated in this study. Electroosmosis permeability of 3.2 × 10−6–4.7 × 10−6, 4.0 × 10−6–4.9 × 10−6, and 3.7 × 10−6–6.8 × 10−6 cm2 V−1 s−1 were observed in the electrokinetic system with Ti, PT, and RT electrodes, respectively. A significant detachment of the coated metals was observed in BMOEEK–PT system with Na2SO4, CA, and NaOH processing fluids. A higher BPA treatment efficiency of 52.2–67.3 % was found in the BMOEEK–RT system, which was 1.4–1.8 times greater than in the EK–Ti system with DW as the processing fluid. The best treatment efficiency was found in the system with NaCl as the processing fluid, which may mostly result from less detachment of the coated metal from electrode and increased hypochlorite (OCl−) generation in the anode reservoir. The primary treatment mechanism in the BMOEEK system with NaCl procession fluid was degradation by anodic oxidation. It was concluded that both the binary metallic electrode and processing fluid played key roles in enhancing the electrochemical degradation of BPA. The electrode characteristics (progressive cyclic voltammogram and SEM micrograph with EDAX), electrokinetic behavior (specimen pH and current density), and treatment mechanism were also discussed in this study.