This paper investigates the transformation behavior of manganese dioxide(MnO2)to the typical organophosphorus pesticide methyl parathion under relative humidity(RH＜5％～100％)conditions.The results show that the primary degradation rate of methyl parathion shows a significant negative correlation with RH,but a significant positive correlation with MnO2 content by using different crystal types of MnO2 as the materials.The degradation behavior of methyl parathion in the reaction system varies widely among different crystalline types of MnO2,and the first-order kinetic degradation rates(kobs)are in the order of a-MnO2＞γ-MnO2＞β-MnO2.The loading ions(PO3-,Ca2+and Mn2+)investigated all significantly inhibit the degradation reaction rate of methyl parathion,among which,Mn2+has the most significant inhibition effect.The transformation pathway of methyl parathion by MnO2 under RH conditions mainly consists of hydrolysis and oxidation,with the hydrolysis product being p-nitrophenol and the oxidation product being methyl paraoxon.The results of this study confirm that RH of the actual soil layer significantly affects the transformation behavior of manganese oxides towards organic phosphorus pesticides,which has reference value for understanding the fate behavior of such pollutants in the natural environment.
维普
万方数据