Anodic oxidation of diuron using Co3O4/graphite composite electrode at low applied current

Abstract

Economical and highly performed anode material is the critical factor affecting the efficiency of anodic oxidation toward organics. In this work, the graphite felt, a common carbonaceous electrode material, is etched by cobalt oxide to fabricated Co3O4/graphite composite anode to eliminate diuron in aqueous solution. The surface morphology, composition and structure of the Co3O4/graphite composite anode are characterized by scanning electron microscope, X-ray photoelectron spectroscopy and X-ray diffraction. Low-current degradation of diuron is achieved in an anodic oxidation process using Co3O4/graphite composite anode. The influence of the applied current density, initial pH value and initial concentration of diuron on the oxidation efficiency are investigated and optimized. The prepared Co3O4/graphite composite anode exhibited excellent activity for oxidation of 20 mg L−1 diuron, obtaining 100% removal efficiency within 14 min under the condition of applied current density 3 mA cm−2 and initial pH 2.0. The process is confirmed to possess a non-radical mechanism in which the diuron is oxidized at the catalytic sites of composite anode under the synergy effect of Co3O4/graphite composite and anodic current. The accelerated service life test proved good electrochemical stability of the prepared Co3O4/GF composite electrode. The low energy demand and use of cheap graphite substrate endow the anodic process based on Co3O4/graphite composite anode in this work with great application prospect to effective removal of diuron.