摘要
采用有机溶剂萃取法(OSE)对高浓度石油污染土壤进行修复,经过精馏回收绝大部分原油,有机溶剂经分离后循环使用。采用批实验法,以土壤-有机溶剂体系为研究对象,模拟物理化学修复过程,建立了脱附等温曲线并确定了脱附类型;研究了石油污染物在土壤-有机溶剂两相间的迁移规律。考查了液固比SSR对萃取的影响。结果表明,复合溶剂可以使土壤中约80%的石油污染物在4～5min内得到脱附,20min达到脱附平衡;Freundlich模型可以很好地描述石油污染物在土壤中的脱附行为,并计算出复合溶剂和乙酸乙酯的脱附平衡常数K分别为:0.0009和0.0015,结果显示复合溶剂对石油污染物的迁移效果高于乙酸乙酯,符合相似相溶原理。液固比SSR对脱附等温线影响明显,平衡常数随液固比增大而减小,即SSR越大脱附效果越好。当SSR由6∶1提高到8∶1时,平衡常数变化很小。综上所述,复合溶剂对土壤中石油污染物的脱附行为符合Freundlich模型,常温下液固比为6∶1时,5min脱油率达80%,20min达90%～95%。考虑后期溶剂回收成本建议液固比在3∶1到5∶1之间为宜。
Oil-contaminated soil with high concentration was repaired by organic solvent extraction （OSE）. The majority of crude oil was recovered by distillation and organic solvent was recycled by separation. The physical and chemical repair process was simu- lated in the soil - organic solvent system by using the batch experimental method. The desorption isotherm and the desorption model were determined. The migration of oil pollutants in soil and organic solvent phases was studied. The impact of solution-to-solid ra- tion （SSR） on the extraction was examined. The results showed that about 80% of contamination was desorped by composite solvent within 4-5 minutes and the desorption reached balance after 20 minutes. Freundlich model could accurately describe the desorption behavior. The desorption equilibrium constant K of composite solvent and ethyl acetate is 0.000 9 and 0.001 5 respectively. The re- sults showed that the migration effect of composite solvents was more obvious, which accorded with the principle of similar com- patibility. The effect of SSR on desorption isotherms line was apparent. Equilibrium constant decreased with increased SSR. When the SSR was increased from 6 ： 1 to 8 ： 1, the equilibrium constant changed a little. To sum up, desorption behavior of oil pollutants accorded with the Freundlich model. Under room temperature and SSR 6 ： 1, the oil removal rate reached 80% within 5 minutes and 90%-95% after 20 minutes. Considering the cost of solvent recovery, the appropriate SSR was between 3 ： 1 and 5 ： 1.
出处
《生态环境学报》
CSCD
北大核心
2009年第3期939-943,共5页
Ecology and Environmental Sciences
基金
国家"863"计划重点项目(2007AA061202)
国家自然科学基金项目(50879053)
关键词
石油污染物
土壤
脱附
液固比
petroleum contamination
soil
desorption
SSR
