Kinetic modeling of a solar photo-electro-Fenton process for treating petroleum refinery wastewater

Abstract

The mineralization kinetics of petroleum refinery wastewater (PRW) released from Iraq's AL-Smood petroleum refinery plant by a solar photo-electro-Fenton (SPEF) process were evaluated. A new configuration of the electrochemical system was adopted in which an electro-Fenton (EF) cell was combined with a solar collector thermo-reactor and operated the system at a batch recirculation mode. The EF cell is a tubular electro-Fenton reactor composed of two concentric porous graphite electrodes provided with an air diffuser. Impacts of operating factors such as current density, Fe2+ concentration, and NaCl addition on the efficiency of COD removal (RE %), specific energy consumption (SEC), and pseudo-first-order rate constant (kapp) were investigated. Results showed that increasing each current density, Fe2+, and NaCl concentrations improves the removal efficiency and Kapp with a reduction in SEC. All COD decays followed pseudo-first-order kinetics with a regression fitting (R2) greater than 0.99. Results confirmed the ability of the present system to decrease COD from 375 ppm to 30 ppm within 90 min when it is operated at an applied current density of 30 mA/cm2, Fe2+ concentration of 0.5 mM, and NaCl addition of 1 g/L in which an SEC value not exceeded 73.4 kWh/kg COD is needed.

Keywords

• Solar-photo-electro-Fenton
• Pseudo first order kinetics
• COD removal
• Petroleum refinery wastewater
• Advanced oxidation process