Zhou Tao, Zhao Minhui, Zhao Xin, Guo Yanyan, Zhao Youcai
The State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, 1515 North Zhongshan Rd. (No. 2), Shanghai, 200092, PR China.
School of Chemical Biology and Environment, Yuxi Normal University, Yuxi 563100, China.
Chemosphere. 2021 Jul;275:129984. doi: 10.1016/j.chemosphere.2021.129984. Epub 2021 Feb 20.
Soil contamination by heavy metals constitutes a serious global environmental problem, and numerous remediation technologies have been developed. In this study, a novel soil remediation agent, namely composite hydrogel (leftover rice-g-poly(acrylic acid)/montmorillonite/Urea, LR-g-PAA/MMT/urea), was prepared based on free radical polymerization cross-linking technology. Experimental results indicated that the LR-g-PAA/MMT/urea dosage increased from 0% to 10%, the oxidizable state proportions of Cd, Cu, Pb and Zn in contaminated soil increased from 8.3%, 23.7%, 54.0% and 11.4%-71.3%, 61.0%, 76.5%, and 27.9%, respectively. Compared with control experiment, the residue state growth rate were 56.6%, 23.4% and 39.8% for Cu, Pb and Zn respectively with 10% dosage of composite hydrogel. Simultaneously, the LR-g-PAA/MMT/urea was also seen to enhance soil fertility, including organic matter content, cation exchange capacity, and N and P contents. Pot experiments for biological toxicity suggested that the addition of hydrogel weakened the toxic effect of heavy metals on cotton seeds, and the action effect was increasingly visible with the increase of hydrogel dosage. The analysis of the mechanism involved suggested that the organic matter and its possessed characteristic functional groups could weaken the biological toxicity via complexation, adsorption, and ion exchange. Overall, the synthesized composite hydrogel exhibits great potential for the simultaneous remediation and fertility improvement of heavy metal contaminated soil.
重金属对土壤的污染是一个严重的全球环境问题，人们已经开发了许多修复技术。在本研究中，基于自由基聚合交联技术制备了一种新型土壤修复剂，即复合水凝胶（剩米饭-g-聚丙烯酸/蒙脱石/尿素，LR-g-PAA/MMT/尿素）。实验结果表明，当LR-g-PAA/MMT/尿素用量从0%增加到10%时，污染土壤中Cd、Cu、Pb和Zn的可氧化态比例分别从8.3%、23.7%、54.0%和11.4%增加到71.3%、61.0%、76.5%和27.9%。与对照实验相比，在复合水凝胶用量为10%时，Cu、Pb和Zn的残留态增长率分别为56.6%、23.4%和39.8%。同时，LR-g-PAA/MMT/尿素还能提高土壤肥力，包括有机质含量、阳离子交换容量以及氮和磷的含量。生物毒性盆栽实验表明，添加水凝胶可减弱重金属对棉花种子的毒性作用，且随着水凝胶用量的增加，这种作用效果愈发明显。对其作用机制的分析表明，有机质及其所含的特征官能团可通过络合、吸附和离子交换减弱生物毒性。总体而言，合成的复合水凝胶在重金属污染土壤的同步修复和肥力提升方面具有巨大潜力。
