Homogeneous oxidation of aqueous solutions of atrazine and fenitrothion through dark and photo-Fenton reactions

Abstract

The homogeneous catalytic oxidation of atrazine and fenitrothion in single compound-containing solutions and in mixture, in pure water, was investigated in dark and light-driven oxidation systems using H2O2 as the oxidant and Fe(II) as the catalyst. It was shown that the degradation during the dark Fenton reactions takes place during the first 2h and further prolongation of the reaction time does not lead to enhanced removals. The same holds true for the light-driven reactions. With the photo-Fenton reaction, fenitrothion was completely mineralized while the TOC contained in the atrazine solution was removed by 57%. Both compounds in their parent form were completely eliminated from the first 5min of the oxidation both when being in the single-containing solutions and in their binary mixture. The oxidation of the TOC in the atrazine solution follows a two-stage second-order kinetic behavior which is attributed to the complex reaction pathways occurring during the oxidation while that of the TOC in the fenitrothion solutions follows a pseudo-first order degradation kinetic and that of binary mixture a two-stage degradation kinetics. The results obtained in this study, clearly indicate that the light-driven Fenton oxidation can be very efficient for the removal of atrazine and especially fenitrothion from polluted waters. "