Photoelectrocatalysis/photoelectro-Fenton system based on cone-like TiO2/nickel foam photoanode for efficient degradation of carbamazepine: Comparison with DSA

Abstract

To degrade refractory organics in wastewater more efficiently and with lower energy consumption, cone-like TiO2 was grown on nickel foam (NF) and coupled with natural air-diffusion electrode (NADE) to construct novel photoelectrocatalysis/photoelectro-Fenton (PEC/PEF) system, which could completely remove 10 mg/L of carbamazepine (CBZ) within 30 min (with a pseudo-first-order rate constant (k) of 0.1939 min−1). And the system was driven by only 2 mA of current (1.7 V cell potential) with an electrical energy per order (EEO) of only 0.005 kWh m−3 order-1. It took the lead in contaminant removal and energy consumption when compared with conventional PEF systems based on dimensionally stable anode (DSA). The synergy coefficient of PEC/PEF system was as high as 6.14, which was 6.5 times that of PEF system. The reaction mechanism different from PEF system was revealed, in which e--h+ pairs were generated at TiO2/nickel foam (TiO2/NF) under UV irradiation, e- transferred to NADE enhanced current density thus promoted H2O2 accumulation much more than that using DSA. The direct oxidation of h+ and the more •OH (6.17 μM vs. 5.82 μM) produced by H2O2 utilization were the reasons for higher degradation efficiency in PEC/PEF process. Our PEC/PEF system provides a new idea for low energy consumption and high efficiency removal of pollutants, it is promising for the application to the treatment of refractory organics in wastewater.