Competitive Anodic Oxidation of Methyl Paraben and Propylene Glycol: Keys to Understand the Process

This work focuses on the competitive oxidation of two very different molecules, when they underwent electrochemical oxidation with diamond electrodes. To shed light on the mechanisms of this competitive oxidation, solutions containing methyl paraben and propylene glycol at different ratios are electrolyzed (using sulfate or chloride supporting electrolytes). Results obtained pointed out that removal of both species can be easily attained by the electrochemical process, being promoted the mineralization by the action of the sulfate derivative products and the formation of chlorinated hydrocarbons by the action of chlorine oxidants, although the mechanisms of the oxidation do not depend on the primary anion contained in the waste. The higher the concentration of species to be oxidized, the higher is the amount of intermediates and the slower is the mineralization the ratio influences. An important outcome is that there is a limit concentration in each one organic compound interferes on the degradation of a pollutant. Thus, the interference effect of PG on MeP oxidation was only observed for low MeP/PG ratios.