热脱附对多环芳烃和重金属复合污染土壤的影响  

Effects of thermal desorption on the complex contaminated soils of polycyclic aromatic hydrocarbons and heavy metals

作　　者：吴秉泽 张文文 刘昭玥 马福俊[2] 李海波[1] 谷庆宝 WU Bingze;ZHANG Wenwen;LIU Zhaoyue;MA Fujun;LI Haibo;GU Qingbao(School of Resources and Civil Engineering,Northeastern University;Department of Soil Pollution and Control,Chinese Research Academy of Environmental Sciences)

机构地区：[1]东北大学资源与土木工程学院 [2]中国环境科学研究院土壤污染防治技术研究室

出　　处：《环境工程技术学报》2024年第1期121-129,共9页Journal of Environmental Engineering Technology

基　　金：国家重点研发计划项目(2019YFC1803800)。

摘　　要：热脱附技术被广泛用于污染场地修复,但其对多环芳烃(PAHs)与重金属复合污染土壤的综合影响仍不清楚。选用PAHs和重金属复合污染模拟土壤,探究热脱附温度(220~400℃)和停留时间(5~60 min)对土壤中PAHs的影响,分析空气与氮气气氛下热脱附温度(310、340和370℃)对土壤中重金属Cu、Pb、As和Cd形态分布的影响。结果表明:随热脱附温度和停留时间的增加,土壤中PAHs去除率显著增加;低环PAHs占比逐渐减少,而高环PAHs占比逐渐增加。在2种气氛热脱附后,Cu、Pb和As弱酸提取态占比略有增加,而Cd弱酸提取态占比显著降低;可还原态和可氧化态的转化趋势具有差异性。随着热脱附温度的升高,Cu、Pb、As和Cd 4种重金属的残渣态占比均逐渐增加,说明热脱附有利于4种重金属的固定。相较于空气,氮气条件下4种重金属可氧化态和残渣态占比均增加;Cu和Pb可还原态占比显著降低,而As可还原态占比有所降低,Cd可还原态占比变化不大。氮气更有利于Cu、Pb和Cd的稳定;相反,空气更有利于As的稳定。Thermal desorption technology is widely used for the remediation of contaminated sites.However,the combined effects of thermal desorption on the complex contaminated soils of polycyclic aromatic hydrocarbons(PAHs)and heavy metals were still unclear.The complex contaminated simulated soils of PAHs and heavy metals were selected to investigate the effects of thermal desorption temperature(220-400℃)and residence time(5-60 min)on PAHs in the soil and to analyze the effects of thermal desorption temperature(310,340,and 370℃)on the morphological distribution of heavy metals(Cu,Pb,As,and Cd)in soil under air and nitrogen atmosphere.The results showed that the removal of PAHs from contaminated soil increased significantly with the increase in thermal desorption temperature and residence time.The proportion of low-ring PAHs gradually decreased while that of highring PAHs gradually increased.After thermal desorption treatment in both atmospheres,the proportion of Cu,Pb,and As weakly acid-extracted states increased slightly,while the proportion of Cd weakly acid-extracted states decreased significantly.The conversion trends of the reducible and oxidizable states were different.The proportion of residue states of four heavy metals,Cu,Pb,As,and Cd,increased gradually with the increase of thermal desorption temperature,which indicated that thermal desorption was beneficial to the immobilization of the four heavy metals.Compared with air,the proportions of oxidizable and residual states of four heavy metals increased under nitrogen conditions.The proportions of Cu and Pb reducible states decreased significantly,while the proportions of As reducible states decreased and the proportions of Cd reducible states did not change significantly.These results showed that nitrogen was more favorable for the stabilization of Cu,Pb,and Cd.On the contrary,the air was more beneficial to the stabilization of As.

关 键 词：热脱附 多环芳烃(PAHs) 重金属 形态转化 

分 类 号：X524[环境科学与工程—环境工程]