REMOVAL EFFICIENCY AND MECHANISM OF ATRAZINE FROM CONTAMINATED SOIL BY PERSULFATE AND ASCORBIC ACID
The efficiency,influencing factors,and mechanism of removing atrazine from soil by ascorbic acid/persulfate were studied.When the concentrations of ascorbic acid and persulfate were 10 and 30 mmol/L,respectively,the degradation ratio of atrazine in soil achieved 92.4％at a pH of 3.0.The co-existing inorganic anions(Cl-and HCO3-)could inhibit the degradation of atrazine.Low concentrations of dissolved organic matter(0 to 2.5 mg/L)could promote the degradation of atrazine,while high concentrations of dissolved organic matter(＞5 mg/L)could inhibit the oxidation of atrazine.On the one hand,ascorbic acid could directly activate persulfate to generate sulfate radicals and hydroxyl radicals.On the other hand,ascorbic acid could promote the release of iron ions from the soil and the cycle of Fe2+/Fe3+,which indirectly enhances the activation of persulfate.In addition,ascorbic acid could enhance the desorption of atrazine from the soil and reduce the mass transfer resistance between atrazine and oxidative radicals,which was beneficial for promoting atrazine oxidation.The degradation pathways of atrazine in the ascorbic acid/persulfate system mainly involved dealkylation oxidation,dechlorination,and hydroxylation.
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