College of Sciences, Nanjing Agricultural University, Nanjing 210095, PR China.
J Hazard Mater. 2011 Sep 15;192(3):1533-8. doi: 10.1016/j.jhazmat.2011.06.076. Epub 2011 Jul 1.
The soluble Cr(III) is likely to be complexed with organic ligands in ligand-rich soil. Cr(VI) chemical reduction by organic acids and bioreduction by microorganisms can produce soluble Cr(III)-organic acids complexes. Thus, it is of great significance to investigate the absorption and mobility of Cr(III)-organic acid complexes in soils. In this study, Cr(III)-EDTA and Cr(III)-cit were prepared and purified, and then were examined for adsorption and mobility. The results demonstrated that Cr(III) was strongly bound to soil, while Cr(III)-organic acid complexes had no or slight interaction with soils since Cr(III)-EDTA and Cr(III)-cit complexes mainly existed as the forms of Cr(III)-EDTA and [Cr(III)-cit], respectively, under the tested conditions with initial pH 4.0-9.0. The adsorption of Cr(III) increased but that of Cr(III)-organic acid complexes decreased with the content of soil organic matter. Compared with Cr(III)-EDTA, the mobility of Cr(III)-cit in soil columns was reduced, due to the specific adsorption between soils and Cr(III)-cit which contained one free hydroxyl group.
可溶性 Cr(III)可能与配体丰富的土壤中的有机配体络合。有机酸对 Cr(VI)的化学还原和微生物的生物还原可以产生可溶性 Cr(III)-有机酸配合物。因此，研究 Cr(III)-有机酸配合物在土壤中的吸收和迁移具有重要意义。本研究制备和纯化了 Cr(III)-EDTA 和 Cr(III)-柠檬酸，并对其吸附和迁移进行了考察。结果表明，Cr(III)与土壤强烈结合，而 Cr(III)-有机酸配合物与土壤几乎没有相互作用，因为在初始 pH 值为 4.0-9.0 的测试条件下，Cr(III)-EDTA 和 Cr(III)-柠檬酸配合物主要以Cr(III)-EDTA和[Cr(III)-柠檬酸]的形式存在。Cr(III)的吸附随着土壤有机质含量的增加而增加，但 Cr(III)-有机酸配合物的吸附则减少。与 Cr(III)-EDTA 相比，Cr(III)-柠檬酸在土壤柱中的迁移性降低，这是由于土壤与含有一个游离羟基的 Cr(III)-柠檬酸之间存在特殊吸附。
