Phenol Reduction of Petroleum Refinery Wastewater Using Electro-Coagulation/Electro-Oxidation Technique

Document Type : Research Paper

Authors

Chem. Eng. Dept., University of Babylon, Babil, Iraq.

Abstract

Water pollution from industrial waste, toxic biological waste, and crude oil refining wastewater: All of these pollutants are released into the environment and pose a major problem today due to their toxic organic and inorganic contaminants. The study found that two electrical methods, electro-coagulation (EC) followed by electro-oxidation (EO) and electro-oxidation alone, effectively reduced organic phenol (C₆H₅OH) levels in oil-refining wastewater from Najaf refineries in Iraq. Both methods achieved remarkable success, though with differences in the factors affecting dissolved phenol removal. The work was done using aluminum and graphite electrodes as the cover of the electric cell and steel (SS) electrodes as the cathode of the cell, made of resistant plastic, in the first method, and graphite electrodes as the anode of the cell with steel (SS) electrodes in the other method. The initial concentration of phenol in the treated water was 50 ppm under the following conditions for both methods: electric current density of 10, 15, and 20 mA/cm², sodium chloride (NaCl) with concentration of 0, 1.5, and 3 g/l, and acidity of 3, 7, and 10 pH, with a fixed time of 1 hour for the EC process and 2.5 hours for the EO process for the first method, while in the other method, the time was varied from 2-4 hours. The results showed that the removal rate was directly proportional to the high current density and NaCl concentration under mild acidic conditions for the first method, with the optimum conditions for the removal process being a current density of 20 mA/cm2, pH 7, and a NaCl concentration of 3 g/L. A removal rate of 95.05% was achieved for the first method under the aforementioned conditions. The results for the removal rate in the second method were obtained under the following conditions: a current density of 15 mA/cm2, a pH of 3, a NaCl concentration of 3 g/L, and a time period of 3 hours. A removal rate of 96.3% was achieved under the mentioned conditions. Optimization tests were performed using the response surface methodology with Box-Behnken design to identify key operational factors influencing phenol removal from wastewater.

Keywords

Main Subjects

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Journal of Chemical and Petroleum Engineering
Volume 60, Issue 1
June 2026
Pages 23-44

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History

  • Receive Date: 21 June 2025
  • Revise Date: 05 October 2025
  • Accept Date: 13 October 2025

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