Abstract：
Soil heavy metal pollution is an important issue that affects human health and ecological well-being. In-situ thermal treatment techniques, such as self-sustaining smoldering combustion (SSS), have been widely studied for the treatment of organic pollutants. However, the lack of fuel in heavy metal-contaminated soil has hindered its application. In this study, we used corn straw as fuel to investigate the feasibility of SSS remediation for copper and lead in heavy metal-contaminated soil, as well as to explore the remediation mechanism. The results of the study showed that SSS increased soil pH, electrical conductivity (EC), total phosphorus (TP), total potassium (TK), rapidly available phosphorus (AP), and available potassium (AK), while decreasing total nitrogen (TN), alkali-hydrolyzed nitrogen (AN), and cation exchange capacity (CEC). The oxidation state of copper (Cu) increased from 10% to 21%-40%, and the residual state of lead (Pb) increased from 18% to 51%-73%. The Toxicity characteristic leaching procedure (TCLP) of Cu decreased by a maximum of 81.08%, and the extracted state of Diethylenetriaminepentaacetic acid (DTPA) decreased by 67.63%; the TCLP of Pb decreased by a maximum of 81.87%, and DTPA decreased by a maximum of 85.68%. The study indicates that SSS using corn straw as fuel successfully achieved remediation of heavy metal-contaminated soil. However, SSS does not reduce the content of copper and lead; it only changes their forms in the soil. The main reasons for the fixation of copper and lead during the SSS process are the adsorption of biochar, complexation with -OH functional groups, binding with π electrons, and the formation of crystalline compounds. This research provides a reference for the application of SSS in heavy metal-contaminated soil and has potential practical implications.
摘要：
土壤重金属污染是影响人类健康和生态福祉的重要问题。原位热处理技术，如自持阴燃(SSS)，已被广泛研究用于有机污染物的处理。然而,重金属污染土壤中燃料的缺乏阻碍了其应用。在这项研究中,以玉米秸秆为燃料,探讨SSS修复重金属污染土壤中铜和铅的可行性,以及对补救机制的探讨。研究结果表明,SSS提高了土壤pH值,电导率(EC)，总磷（TP），总钾（TK），快速有效磷(AP)，和有效钾（AK），在降低总氮(TN)的同时，碱水解氮(AN)，和阳离子交换容量（CEC）。铜(Cu)的氧化态从10%增加到21%-40%,铅（Pb）的残留量从18％增加到51％-73％。铜的毒性特征浸出程序（TCLP）最大降低了81.08%，二乙烯三胺五乙酸（DTPA）的提取状态下降了67.63%；Pb的TCLP最大下降了81.87%，DTPA最大下降85.68%。研究表明，以玉米秸秆为燃料的SSS成功地实现了重金属污染土壤的修复。然而,SSS不会降低铜和铅的含量；它只会改变它们在土壤中的形式。SSS过程中铜和铅固定的主要原因是生物炭的吸附，与-OH官能团络合，与π电子结合，和晶体化合物的形成。该研究为SSS在重金属污染土壤中的应用提供了参考，具有潜在的现实意义。
