Effects of operating parameters on advanced oxidation of diuron by the Fenton’s reagent: A statistical design approach

Advanced oxidation of diuron in aqueous solution by Fenton’s reagent using FeSO4 as source of Fe(II) was investigated in the absence of light. Effects of operating parameters namely the concentrations of pesticide (diuron), H2O2 and Fe(II) on oxidation of diuron was investigated by using Box-Behnken statistical experiment design and the surface response analysis. Diuron oxidation by the Fenton reagent was evaluated by determining the total organic carbon (TOC), diuron, and adsorbable organic halogen (AOX) removals. Concentration ranges of the reagents resulting in the highest level of diuron oxidation were determined. Diuron removal increased with increasing H2O2 and Fe(II) concentrations up to a certain level. Diuron concentration had a more profound effect than H2O2 and Fe(II) in removal of diuron, TOC and AOX from the aqueous solution. Nearly complete (98.5%) disappearance of diuron was achieved after 15 min reaction period. However, only 58% of diuron was mineralized after 240 min under optimal operating conditions indicating formation of some intermediate products. Optimal H2O2/Fe(II)/diuron ratio resulting in the maximum diuron removal (98.5%) was found to be 302/38/20 (mg l−1).