热活化过硫酸盐氧化污染土壤中的石油烃

Chemical Oxidation of Petroleum Hydrocarbon in Contaminated Soil by Thermally Activated Persulfate

石油的开采、运输、储存和使用等过程会导致一些土壤受到石油烃的污染。土壤中的石油烃会对生态安全和人类健康造成潜在危害,因此需要开展土壤修复。本研究采用热活化过硫酸钠氧化处理污染土壤中的石油烃,考察了氧化剂剂量和超声结合热活化对石油烃去除效率的影响,并对石油烃氧化产物以及氧化后土壤理化性质进行了分析。结果表明,当过硫酸钠的用量为2.4 mmol/g土壤时,石油烃的含量从3800 mg/kg降至1175 mg/kg,石油烃的去除效率可以达到69%。石油烃的去除效率随着氧化剂增加呈上升趋势。但当氧化剂的剂量超过2.4 mmol/g土壤时,石油烃的去除效率不再增加。使用超声结合热活化,石油烃的去除效率可以进一步提高。过硫酸盐氧化会使土壤pH显著下降,造成土壤酸化。气相色谱质谱(GC/MS)和傅里叶变换红外光谱(FTIR)分析表明石油烃氧化后可能会生成一些醇和羧酸类含氧产物。石油烃和土壤有机质被氧化成极性小分子更易进入水相,导致水中总有机碳(TOC)含量从52.4 mg/kg增加至79.8 mg/kg。扫描电镜和粒度分析表明氧化处理会改变土壤形貌,使土壤的粒径变小。氧化导致土壤的碳、氢含量减少,硫含量增加。本研究的发现可以为石油烃污染土壤修复提供参考。

The exploitation,transportation,storage and use of petroleum can lead to soil contamination by petroleum hydrocarbons(PHCs),which may cause potential risk to ecological safety and human health,so it is necessary to conduct soil remediation.In this study,PHCs in contaminated soil were oxidized by thermally activated sodium persulfate,and the effects of oxidant dosage and ultrasound combined with thermal activation on the removal efficiency of petroleum hydrocarbons were tested.Oxidation products from petroleum hydrocarbon and soil physiochemical properties after oxidation were investigated.The results showed that when the amount of sodium persulfate was 2.4 mmol/g soil,the concentration of petroleum hydrocarbons decreased from 3800 mg/kg to 1175 mg/kg,and the removal efficiency of petroleum hydrocarbons could reach 69%.The removal efficiency of petroleum hydrocarbons showed an upward trend with the increase of oxidant dosage.However,when the dosage of oxidant exceeded 2.4 mmol/g,the removal efficiency of petroleum hydrocarbons no longer increased.Using ultrasound combined with thermal activation,the removal efficiency of petroleum hydrocarbons could be further increased.Persulfate oxidation significantly decreased soil pH,causing soil acidification.Gas chromatography mass spectrometry(GC/MS)and fourier transform infrared spectroscopy(FTIR)analysis indicated that some alcohols and carboxylic acid compounds might be generated after the oxidation of petroleum hydrocarbons.Petroleum hydrocarbons and soil organic matter were oxidized into small polar molecules,which tended to enter the water phase,causing the total organic carbon(TOC)content in water to increase from 52.4 mg/kg to 79.8 mg/kg.In addition,scanning electron microscopy and particle size analysis showed that oxidation treatment changed soil morphology,and decreased soil particle size.Oxidation decreased soil carbon and hydrogen contents,and increased soil sulfur content.The findings of this study can provide reference for the remediation of petroleum hydrocarbon contaminated soil.