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

[Display omitted] • A novel photocatalysis-ElectroFenton system was applied successfully for treatment wastewater. • The optimum conditions were: current density of 15 mA/c m 2 , Fe²⁺concentration of 0.5 mM, Ti O 2 dosage of 0.7 g/l, and time of 54 min. • A maximum COD removal (RE% = 91.26 %) with lower energy consumption (EECT = 26.86 kWh/ m 3)were achieved. • reaction time was the most effective parameter followed by Ti O 2 dosage, Fe²⁺ concentration, and current density. • EF + UV/Ti O 2 in comparison with UV/Ti O 2 alone results in an enhancement of 23% in RE% and a reduction by 55% of EECT. In the current study, treatment of petroleum refinery wastewater has been successfully achieved using a novel photocatalysis-ElectroFenton 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/ TiO 2) 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), TiO 2 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/ TiO 2 process followed by TiO 2 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, TiO 2 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/ TiO 2 in comparison with UV/ TiO 2 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/TiO 2 and UV/ TiO 2 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/ TiO 2 process. [ABSTRACT FROM AUTHOR]