分级Fenton体系中羟基自由基产量及其氧化土壤中石油污染物的影响因素研究

Production of Hydroxyl Radicals and Removal of Petroleum Pollutants in Soil in Stepwise Fenton System

研究了4个铁浓度条件下、5种分级改性Fenton体系的羟基自由基产率,并考察频繁产生的羟基自由基去除土壤中石油污染物的效果。结果表明,分级Fenton氧化体系中羟基自由基会频繁持续产生,羟基自由基的产量比不分级的传统改性Fenton法提高了20%~40%左右;且分级数越多,羟基自由基产量、频次就越多,其中第1级产量最大,约为1.0~2.0 mmol,第2级次之,约为0.5~1.0 mmol。分级Fenton体系TPH氧化率高达59%,较不分级的改性Fenton法TPH的氧化率提高了26%。此外,研究发现四级改性Fenton体系中各级均匀产生羟基自由基,土壤中石油的氧化效果大幅度提高,表明羟基自由基各级均匀形成、持续氧化对提高分级Fenton氧化石油污染土壤的效果至关重要。

Production of hydroxyl radicals and the oxidation of petroleum contaminated soil in five graded modified Fenton systems were investigated under four iron concentration conditions in order to understand oxidation mechanism of petroleum contaminated soil. The results showed that hydroxyl radicals were frequently and continuously produced in graded modified Fenton system, and the yield of hydroxyl radical in graded modified Fenton system was higher than that of traditional modified Fenton system by 20%-40%. The more the grades were, the higher hydroxyl free radical yield was. In addition, main hydroxyl free radicals（about 1.0- 2.0 mmol） were produced in the first step; 0.5-1.0 mmol hydroxyl free radicals were generated in the second step. Oxidation removal efficiency of TPH in graded modified Fenton system was as high as 59% because of frequency generation of hydroxyl radicals, and it was higher than that of traditional modified Fenton system by 26%. In addition, high TPH removal rate was observed after four graded modified Fenton oxidation because hydroxyl radicals that were slowly generated step by step oxidized crude oil continuously.