Petroleum refinery wastewater treatment using a novel combined electro-Fenton and photocatalytic process

In the current study, treatment of petroleum refinery wastewater has been successfully achieved using a novel photocatalysis-ElectroFen ton system operated at a batch circulation mode and composed from a tubular electro-Fenton reactor provided with a macro-porous graphite air diffusion cathode (MPGADC) combined with a new configuration of photo reactor. The feasibility of the combined electro-Fenton with photo-catalytic process (EF + UV/ TiO2) was evaluated using response surface methodology (RSM) with Box-Behnken design (BBD). Titanium dioxide (Anatase) was used as a photo-catalyst and characterized by x-ray diffractometer (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller surface area (BET). Four main operating variables were studied: current density (5-15 mA/cm2, Fe2+concentration (0.1-0.5 mM), TiO2 dosage (0.1-0.7 g/l), and reaction time (20-60 min). Results revealed that reaction time has the most effective parameter on the EF + UV/ TiO2 process followed by TiO2 dosage, Fe2+concentration, and current density. The optimum operating conditions for maximizing COD removal (RE%) and minimizing the total electrical energy consumption (EECT)) were found to be a current density of 15 mA/cm2, Fe2+ concentration of 0.5 mM, TiO2 dosage of 0.7 g/l, and a reaction time of 54 min in which COD removal of 91.26 % was achieved with claiming EECT of 26.86 kWh/m3. Results revealed a vital improvement of using EF + UV/ TiO2 in comparison with UV/ TiO2 alone where an enhancement of 23% in RE% and a reduction by 55% of EECT were observed. Furthermore, a kinetic study was performed for EF + UV/TiO2 and UV/ TiO2 alone in which the results revealed that decay of COD obeyed a pseudo-first-order kinetic for the two processes with a high-rate constant for EF + UV/ TiO2 process.(c) 2023 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.