土壤多环芳烃（PAHs）污染已严重威胁生态环境安全和人类生命健康。通过异位热脱附试验探究了PAHs初始浓度、土壤含水率和土壤粒径对脱附效率的影响，并采用一级、二级动力学和指数衰减模型对PAHs热脱附过程进行拟合，以探究土壤中PAHs热脱附的去除机制。结果表明，在同等条件下，随着PAHs初始浓度的增加，脱附效率随之升高，且在热脱附20~40 min时提高初始浓度可明显提高PAHs的去除率。土壤含水率对于PAHs不同组分的作用具有一定的差异性，当土壤含水率为16%，萘（Nap）、菲（Phe）和蒽（Ant）达到最佳去除率，而荧蒽（Fla）和芘（Pyr）最大去除率对应的土壤含水率为13%。在相同脱附条件下，土壤粒径越小，土壤中PAHs的去除率越高。研究发现指数衰减模型对PAHs各组分的脱附过程具有更好的拟合效果。土壤中PAHs热脱附主要分为两个阶段：①PAHs受到土壤中水的蒸发作用从土壤颗粒表面快速蒸发；②PAHs的蒸发速率受到土壤孔隙内部扩散的限制，以非常缓慢的速度从土壤中脱除。

Soil polycyclic aromatic hydrocarbons (PAHs) pollution has seriously threatened human life and health and the safety of the ecological environment. The effects of initial PAHs concentration, soil moisture and particle size on the desorption efficiency were investigated by ex-situ thermal desorption experiments, and the primary and secondary kinetic and exponential decay models were used to fit the thermal desorption to explore the removal mechanism of PAHs' thermal desorption in soil. The results showed that the desorption efficiency increased with higher initial PAHs concentration under the same conditions. When the desorption lasted 20-40 min, a significant efficiency improvement was observed. The effects of soil moisture varied with different PAHs components:Nap, Phe and Ant reached optimal removal rate when the moisture was 16%, while the maximum removal rate of Fla and Pyr occurred with 13% moisture. Under the same desorption conditions, the smaller the soil particle size, the higher the removal rate of PAHs in the soil. The results showed that the exponential decay model has a better fitting effect on the desorption process of PAHs components. PAHs' thermal desorption is divided into two main stages:1) PAHs evaporate from soil particle surface with water evaporation; 2) the diffusion within soil pores restricts PAHs' evaporation rate.

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国家自然科学基金项目（42077126）和江苏省地质工程环境智能监控工程研究中心开放基金项目（2021-ZNJKJJ-02）资助。