针铁矿-富里酸复合材料对铅镉污染土壤的钝化修复性能

珠三角地区作为粤港澳大湾区的重要经济区域,工矿企业多,土壤重金属污染状况较为严重,且多以铅镉复合污染为主,研发安全高效的重金属修复材料与技术对保障区域环境质量和人居安全具有重要意义.本文拟采用钝化修复技术,以南方红壤中典型矿物针铁矿为主体,制备了针铁矿-富里酸复合材料,并将其应用于铅镉复合污染土壤的钝化修复.结果表明,复合材料中富里酸所占的质量分数越高,对铅镉钝化作用效果越好;土壤中铅镉的钝化率(IE)随钝化时间的延长而增加,并趋于稳定;钝化修复后可交换态及碳酸盐结合态Pb含量降低,残渣态Pb含量增加,土壤中Cd可交换态含量降低,铁锰氧化态及残渣态含量显著增加;钝化修复后土壤CEC、速效钾及铵态氮含量均有所提高;综合评价认为针铁矿-富里酸复合材料应用于红壤铅镉钝化修复有效可行.

Immobilization Impact of Goethite-Fulvic Acid Composites on Pb-Cd Contaminated Soil

The Pearl River Delta region is the major economic zone of the Greater Bay Area:it presents a large number of industrial-mining enterprises and is interested by severe heavy metal pollution (mainly caused by Pb and Cd). The research and development of safe and efficient heavy metal remediation materials and technologies is fundamental in order to guarantee regional environmental quality and habitat safety. Goethite-fulvic acid composites were prepared using goethite minerals present in the red soils of the Pearl River Delta region by passivation repair, and were applied to immobilize Pb and Cd in a co-contaminated soil. The results showed that a higher ratio of fulvic acid in the composites enhanced the immobilization effect on Pb and Cd:the immobilization efficiency (IE) of Pb and Cd increased with the passivation time, and then stabilized. Additionally, the exchangeable and carbonate-bound fractions of Pb and Cd in the soil decreased, while the Fe-Mn oxide-bound and residual fractions increased. The cation exchange capacity (CEC), as well as the available K and NH₄⁺-N in the soil increased after the application of the composite materials. We conclude that goethite-fulvic acid composites can be effectively applied to the remediation of Pb-Cd contaminated soil.