Oxidative degradation of phenolic wastewater by electro-fenton process using MnO2-graphite electrode

Abstract A manganese dioxide (MnO2) electrode on graphite substrate was prepared, characterized, and used for the degradation of phenolic wastewater by an electrochemical advanced oxidation process. The prepared electrode was characterized by X-ray diffraction, X-ray fluorescence, scanning electron microscopy, energy dispersive spectroscopy, and atomic forced microscopy. The deposited material consisted mainly ofγ-MnO2with an average crystal size of 14.3 nm. Some cracks were observed on the surface, and their sizes were measured. Application of the prepared electrode in wastewater remediation by electro-Fenton process was investigated. The effects of the operating conditions, namely, temperature (30–60 °C), current density (2–8 mAcm−2), ferrous iron concentration (0.05–0.4 Mm), and time (1–6 h), were studied. Notably, chemical oxygen demand (COD) removal from wastewater increased significantly with increasing values of the operating parameters. After 6 h, it was found that 88.01% of the initial COD reduced when the solution treated by applying 8 mAcm−2 at 60 °C and 0.4 mM Fe2+. The energetic parameters and kinetics of COD degradation were also investigated.