Oxidative degradation of atrazine in aqueous solution by UV/H2O2/Fe2+, UV/S2O82-/Fe2+ and UV/HSO5-/Fe2+ processes: A comparative study

The degradation of atrazine, a widely used endocrine disrupting, carcinogenic and persistent herbicide, was investigated by photo-Fenton and photo-Fenton-like advanced oxidation technologies (AOTs): UV/H2O2/Fe2+, UV/S2O82-/Fe2+ and UV/HSO5-/Fe2+. The study was carried out at two pH value conditions, i.e., pH 3.0 and pH 5.8. At pH 3.0, UV/HSO5-/Fe2+ was found to be the most efficient technology whereas UV/S2O82-/Fe2+ was observed to be the most effective at pH 5.8. The degradation of atrazine followed pseudo-first-order reaction with the highest observed rate constant of 2.00 × 10−2 cm2/mJ in UV/HSO5-/Fe2+ system at the initial concentrations of 4.64 μM atrazine, 46.4 μM HSO5- (PMS) and 35.81 μM Fe2+. The UV fluence required for the complete removal of 4.64 μM atrazine at initially 92.80 μM of oxidant and 8.95 μM of Fe2+ concentrations at pH 3.0 was found to be 480, 720 and 960 mJ/cm2 in UV/HSO5-/Fe2+, UV/S2O82-/Fe2+ and UV/H2O2/Fe2+ systems, respectively. Humic and fulvic acids were found to negatively impact the degradation of atrazine. The removal of TOC was not significant unless a high UV fluence was applied. At an initial concentration of 18.56 μM atrazine, 1856.00 μM oxidant and 17.91 μM Fe2+, a 62.94%, 47.10% and 44.09% decrease in TOC was achieved at a UV fluence of 6000 mJ/cm2 in UV/PS/Fe2+, UV/PMS/Fe2+ and UV/H2O2/Fe2+ systems, respectively. Nevertheless, it is suggested in this study that photo-Fenton and photo-Fenton-like technologies are capable of removing atrazine from water efficiently.

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• Removal of atrazine was studied by UV/H2O2/Fe2+, UV/S2O82-/Fe2+ and UV/HSO5-/Fe2+.
• UV/HSO5-/Fe2+ was found to be the most efficient at pH 3.0 in degrading atrazine.
• UV/S2O82-/Fe2+ showed to be the most efficient at pH 5.8.
• Natural organic matter negatively impacted the efficiency of these processes.
• The stability of S2O82- possibly led to a higher removal of TOC by UV/S2O82-/Fe2+.