化学氧化法修复TPH污染土壤的效果比较及工艺研究

以TPH污染土壤为研究对象,研究了不同化学氧化体系对TPH污染土壤的修复效果及影响因素。研究表明:Fenton、类Fenton及碱活化过硫酸盐3个体系都对TPH污染土壤有较好的修复效果。柠檬酸的加入改善了Fenton体系的催化作用,类Fenton体系降解效果最佳。TPH在类Fenton及碱活化过硫酸盐体系中的降解符合准一级反应动力学,提高H₂O₂、柠檬酸和过硫酸盐的浓度均有利于TPH的降解。强化混合、分次投加氧化剂及减小土壤粒径均可以提高TPH的降解效率,节约氧化剂用量。类Fenton体系中有效成分主要为·OH,碱活化过硫酸盐体系中除了·OH外,还存在SO■·或O■·等的作用,因此氧化剂利用率较高。

EFFECT AND PROCESS RESEARCH FOR TPH CONTAMINATED SOIL REMEIDANTION BY CHEMICAL OXIDANTION

In this study, the remediation effect of several chemical oxidation systems on TPH-contaminated soils were evaluated, and some impact factors were studied as well. The results showed that Fenton, Fenton-like and alkali-activated persulfate systems showed good TPH remediation performance. Since the addition of citric acid significantly improved the catalytic activity of Fenton system, the Fenton-like system showed the best TPH degradation performance. The TPH degradation in Fenton-like and alkali-activated persulfate systems followed the pseudo-first-order kinetics. Increasing the concentration of hydrogen peroxide, citric acid and persulfate could enhance the degradation of TPH. It was proved that intensifying mixing, adopting sequential addition of oxidants and reducing soil particle size could obviously improve the degradation effect of TPH with lower amount of oxidants. Moreover, the experimental results confirmed that the main active free radical in Fenton-like system was ·OH, while in the alkali-activated persulfate system, besides ·OH, the presence of SO₄-· or O₂-·, and other presenting free radicals also made greater advantage of the oxidants.