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

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 2 h 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 5 min 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.