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

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 of gamma-MnO2 with 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 degrees 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 degrees C and 0.4 mM Fe2+. The energetic parameters and kinetics of COD degradation were also investigated.