Wang Lei, Liu Xunjie, Wang Yangyang, Wang Xiaoshu, Liu Jin, Li Tongtong, Guo Xiaomeng, Shi Chao, Wang Ying, Li Shaofeng
School of Materials and Environmental Engineering, Institute of Urban Ecology and Environment Technology, Shenzhen Polytechnic, Shenzhen 518055, PR China; Eco-Environmental Science Center (Guangdong, Hong-Kong, Macau), Guangzhou 510555, PR China.
Eco-Environmental Science Center (Guangdong, Hong-Kong, Macau), Guangzhou 510555, PR China; Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, Tianjin 300134, PR China.
Sci Total Environ. 2023 Dec 10;903:166498. doi: 10.1016/j.scitotenv.2023.166498. Epub 2023 Aug 24.
Improper treatment of heavy metal-enriched biomass generated after phytoremediation might cause secondary pollution in soil and water. At present, the pyrolysis process is an effective method for the treatment of phytoremediation residue. In this study, Ni-enriched biomass was prepared using hydroponics method and further pyrolyzed at different temperatures (300-700 °C). At low pyrolysis temperatures (below 500 °C), carbonate precipitation was the main reason of Ni stabilization in biochar. Nevertheless, the formed phosphate and aluminosilicate were important factors for immobilizing Ni in biochar at high pyrolysis temperatures (above 500 °C). Moreover, the oxidizable (F3) and residual (F4) components of Ni in biochar increased with increasing pyrolysis temperature, which indicated that higher pyrolysis temperature could effectively reduce the bioavailability of Ni in biochar. The results of deionized water, acidification, oxidation, and toxic characteristic leaching procedure (TCLP) experiments showed that pyrolysis temperature was the dominant factor for Ni stabilization in biochar. The ecological risk assessments further proved that pyrolyzed Ni-enriched biochar could reduce the environmental toxicity and potential ecological risks of Ni. In the soil simulated experiment, the soil microenvironment gradually promoted the transformation of Ni in BC from bioavailable fraction to stable fraction. Overall, this study would expose more reasonable reference for the long-term storage of phytoremediation residues.
植物修复后产生的重金属富集生物质若处理不当，可能会导致土壤和水体的二次污染。目前，热解过程是处理植物修复残渣的有效方法。本研究采用水培法制备了镍富集生物质，并在不同温度（300 - 700℃）下进行进一步热解。在低热解温度（低于500℃）下，碳酸盐沉淀是生物炭中镍稳定化的主要原因。然而，在高热解温度（高于500℃）下，形成的磷酸盐和铝硅酸盐是生物炭中固定镍的重要因素。此外，生物炭中镍的可氧化态（F3）和残渣态（F4）成分随热解温度升高而增加，这表明较高的热解温度可有效降低生物炭中镍的生物有效性。去离子水、酸化、氧化和毒性特征浸出程序（TCLP）实验结果表明，热解温度是生物炭中镍稳定化的主导因素。生态风险评估进一步证明，热解后的镍富集生物炭可降低镍的环境毒性和潜在生态风险。在土壤模拟实验中，土壤微环境逐渐促进了生物炭中镍从生物可利用态向稳定态的转化。总体而言，本研究将为植物修复残渣的长期储存提供更合理的参考。
