Li Qian, Zhong Zhaoping, Yang Yuxuan, Qi Renzhi, Du Haoran, Zheng Xiang
Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, Southeast University, Nanjing, China.
Int J Phytoremediation. 2025;27(7):941-948. doi: 10.1080/15226514.2025.2457510. Epub 2025 Jan 26.
Soil heavy metal contamination and sludge disposal have become globally environmental issues problems of great concern. Utilizing sludge pyrolysis to produce biochar for remediating heavy metal-contaminated soil is an effective strategy to solve these two environmental problems. In this study, municipal sewage sludge and papermaking sludge were used as feedstock to prepare co-pyrolyzed biochar, which was then applied to reduce the toxicity of Cd in soil. The results indicated that the application of co-pyrolyzed biochar significantly increased soil pH, CEC, and enzyme activity, while decreasing the content of available Cd in the soil. Following the application of 3% co-pyrolyzed biochar, the proportion of acid-soluble Cd in the soil decreased to below 46%, as the biochar facilitated the conversion of leachable acid-soluble Cd to stable oxidizable and residual forms through precipitation and complexation. The DFT computational results indicate that the aromatics in co-pyrolyzed biochar can adsorb Cd ions through cation-π interactions, while carboxyl, hydroxyl, aldehyde, and amide groups can provide more electrons for the adsorption of Cd ions, resulting in stronger adsorption capacities. The study findings provide a feasible solution for the resourceful treatment of sludge and the remediation of heavy metal-contaminated soil.
土壤重金属污染和污泥处置已成为全球备受关注的环境问题。利用污泥热解制备生物炭用于修复重金属污染土壤是解决这两个环境问题的有效策略。本研究以城市污水污泥和造纸污泥为原料制备共热解生物炭，然后将其应用于降低土壤中镉的毒性。结果表明，共热解生物炭的施用显著提高了土壤pH值、阳离子交换量和酶活性，同时降低了土壤中有效镉的含量。施用3%的共热解生物炭后，土壤中酸溶性镉的比例降至46%以下，因为生物炭通过沉淀和络合作用促进了可浸出酸溶性镉向稳定的可氧化态和残留态的转化。密度泛函理论计算结果表明，共热解生物炭中的芳烃可通过阳离子-π相互作用吸附镉离子，而羧基、羟基、醛基和酰胺基团可为镉离子的吸附提供更多电子，从而具有更强的吸附能力。研究结果为污泥的资源化处理和重金属污染土壤的修复提供了可行的解决方案。
