Efficient Photoelectrocatalytic Degradation of BTEX Using TiO2/CuO/Cu2O Nanorod-Array Film as the Photoanode and MWCNT/GO/Graphite Felt as the Photocathode

Abstract

Wastewater treatment challenges by conventional methods have necessitated the need for alternative/complementary methods that are environmentally safe and efficient especially towards recalcitrant organic pollutants. In this regard, a novel highly active visible-light responsive photoanode with the ternary hybrid CuO/Cu2O/TiO2 nanorods array film is proposed to enhance electron transfer in the photoelectrocatalytic (PEC) degradation of BTEX (benzene, toluene, ethyl benzene, and xylenes) by combining with MWCNT/GO/GF cathode. Structural, morphological, optical, electrochemical, and elemental analysis of proposed electrodes is investigated in detail. Response surface methodology (RSM) comprising of full-factorial central composite design (CCD) with five factors and five levels has been used to examine the effects of different operating parameters such as electrode distance, current density, treatment time (t), solution pH, and conductivity in a PEC batch reactor. BTEX mineralization in aqueous solution was examined with multiple responses such as chemical oxygen demand (COD) and specific energy consumption. During multiple response optimization, the desirability function approach was employed to concurrently maximize COD removal and minimize energy consumption. At the optimum condition, 81.3% COD removal and 9.5 kWh/kg of COD removed were observed. The photoelectrocatalytic oxidization mechanism of BTEX with proposed anode and cathode was discussed, then the possible degradation pathway of BTEX identified using GC–MS.