环境地球化学国家重点实验室知识库

Clays are promising adsorbents for heavy metal removal from the environment because they are economical, naturally abundant and environmentally stable. Application of natural clays, however, are typically limited due to their adsorption capacity and because they usually possess little redox potential except for some specific clays with special functional groups, restricting their application in the removal and detoxification of oxidized metal ions, such as Cr(VI). In the present study, natural bentonite was modified with thiol and iron functional groups to improve both its adsorption performance and reduction ability. Material characterization techniques confirmed the success of grafting the thiol group and pillaring the reduced Fe in the clay. Batch adsorption tests demonstrated an enhanced Cr-adsorption capability of the functionalized bentonite. Moreover, the reduced product, Cr(III),was accumulated in the reaction system, indicating a decrease in Cr(VI) toxicity due to its reduction to Cr(III)by the reduced iron functional group in the modified clay. Pot experiments, using mustard as the target seedling, further demonstrated that the thiol/Fe-modified clay could efficiently stabilize and detoxify Cr(VI) in the soil, therefore inhibiting its accumulation in the crop tissues and ultimately improving plant growth. The results suggested that this novel clay modified with sulfhydryl and iron might be a promising material for the stabilization and toxicity alleviation of Cr(VI)-contaminated soils.