Effect of Nitrate and Sulfate Contamination on Degradation of Diuron via Electrochemical Advanced Oxidation in a Microreactor

Abstract

The degradation of diuron, which is a toxic herbicide that causes a serious environmental problem in many countries, was performed using electrochemical advanced oxidation process (EAOP) in a microreactor. The influence of nitrate and sulfate contamination on the degradation was investigated. The experimental results clearly indicate that both nitrate and sulfate ions retard diuron degradation. Under the applied current of 1 mA, about 91% of diuron in deionized water is degraded within 100 s of residence time, while the degradation achieved is 79% and 76% when nitrate and sulfate ions are presented in the solution at concentration of 50 mM, respectively. Both ions behave as a scavenger for the reactive hydroxyl radical, although other mechanisms might also involve causing this retarding effect. Nitrate ion participates in diuron degradation causing new reaction pathways, while sulfate does not interfere with the diuron degradation pathway. The presence of ion in the solution also shifts the degradation route from one route to another.