An investigation into advanced oxidation of three chlorophenoxy pesticides in surface water

The performance of Fenton's reagent in removing 2,4-D, MCPA and mecoprop from surface water has been evaluated here. Initial trials were undertaken at a pesticide concentration of 4.5 × 10⁻⁵ mol l⁻¹ in deionised water at pH 3 and two different stoichiometric ratios of pesticide: Fe(II): H₂O₂ (1:1:10, 1:10:10) were evaluated. At the 1:1:10 ratio, ∼10 minutes were required to achieve a 50% removal of the pesticide. At the higher ratio the removal achieved after 1 minute, was >90%. Subsequent experiments studied the performance of Fenton (4.5 × 10⁻⁴ mol l⁻¹ Fe(II): 4.5 × 10⁻⁴ mol l⁻¹ H₂O₂) in surface water spiked with pesticides and the impact of pH on the rate and degree of pesticide degradation was investigated. The removal was significantly improved at pH 3 in comparison to pH 6.5. The effect of Fenton on DOC removal from surface water was followed. Experiments investigated the performance of Fenton at pesticide concentrations of 7.5 × 10⁻⁹ mol l⁻¹ in surface water. Fenton was shown to be an effective treatment for removing low levels of pesticides from surface waters at pH 3 & 4.