Electrochemical Treatment of Petroleum Refinery Wastewater Using SnO2 and Graphite Anodes

Abstract

In recent years, clean water has become increasingly scarce because of the highly consumption by human and industry. Therefore, a huge amount of wastewater was discharged to the environment and their treatment is essential by using cost-effective methods. In this study, wastewater from petroleum refinery was processed by an electrochemical oxidation using two types of anodic materials graphite and SnO₂ film deposited on Cu substrate. SnO₂ anode was prepared from nitrate media and characterized by XRD and SEM. Experiments were conducted to determine the performance of each electrode at a current density of 12 mA/cm² in the absence of NaCl addition. The SnO₂ electrode showed better processing ability than the graphite electrode at the same current density in case of no addition of NaCl. Addition NaCl resulted in increasing the activity of graphite in the treatment of wastewater but never exceeded the efficiency of SnO₂. The best removal of chemical oxygen demand (COD) at a current density of 12 mA/cm² and 150 min was 79% in case of SnO₂ in comparison with 72% in case of using graphite with addition of NaCl. Energy consumption in case of SnO₂ was 9.93 kWh/kg COD which is very low in comparison with the using of graphite (49.6 kWh/kg COD). The decay of COD was found to obey pseudo first order for anodic oxidation using SnO₂ or graphite electrodes.