Condition optimization of pesticide contaminated soils remediation by modified Fenton reagent

Fenton reagent modified by EDTA-2Na was applied to study the chemical oxidation remediation of chlorinated organics and BTEX in pesticide contaminated soils. The effects of EDTA-2Na, H₂O₂, FeSO₄ dosage and H₂O₂ dosing times on pollutants degradation rate were studied. The results showed that the degradation rate of benzene was increased by 29.6 percentage points and that of 1,2-dichlorobenzene by 26.4 percentage points when EDTA-2Na was added in the ratio of 1∶1 to Fe ²⁺. Under the same experimental conditions, the degradation rates of benzene, 1, 2-dichlorobenzene increased with the addition of EDTA-2Na, H₂O₂, FeSO₄, H₂O₂ concentrations, as well as with H₂O₂ dosing times, and then gradually stabilized. The suitable process parameters were identified as follows: H₂O₂ dosage 3.0 mmol∕g, n(H₂O₂)∶n(FeSO₄)∶n(EDTA-2Na)=10∶1∶1, and reaction time 2 hours, and H₂O₂ added within 4 times. Under these conditions, the degradation rate of benzene was high up to 86.0%, and that of 1,2-dichlorobenzene was up to 83.6%.