Comparative Degradation of Atrazine by Anodic Oxidation at Graphite and Platinum Electrodes and Insights into Electrochemical Behavior of Graphite Anode

Abstract

Anodic oxidation capacities of graphite and platinum (Pt) electrodes were investigated for the degradation of the herbicide atrazine in synthetic aqueous medium. The electro-oxidation of atrazine under various supporting electrolytes and applied currents was conducted in an undivided reactor with different electrode materials. The electrochemical behavior between anode material and supporting electrolyte was investigated by means of cyclic voltammetry. Graphite anode exhibited good oxidation capacity for degradation of 10 mg L−1 atrazine in near-neutral pH condition, achieving over 90% removal efficiency in all cases within 60 min. Atrazine removal efficiency of 100% was obtained with graphite anode in 60 min of reaction time at applied current 60 mA, NaCl concentration 0.05 mol L−1, and initial pH 6.8; nevertheless, less than 60% of removal was achieved with Pt anode under the same conditions. Five times consecutive runs demonstrated that the atrazine removal efficiency was obviously increased with the positive polarized graphite anode. Positive polarization of graphite anode during anodic oxidation process functionalizes the surface, generating oxygen-containing functional groups; these functional groups played a catalytic role during the oxidation of substrates. An oxidation pathway was proposed in which atrazine was virtually destroyed by chemisorbed reactive oxygen at the graphite anode.