Beijing Key Laboratory of Water Resources and Environmental Engineering, School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China.
Beijing Key Laboratory of Water Resources and Environmental Engineering, School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China.
Chemosphere. 2019 May;222:511-516. doi: 10.1016/j.chemosphere.2019.01.160. Epub 2019 Jan 30.
Hexavalent chromium [Cr(VI)] contamination poses a significant environment hazard due to its high toxicity, solubility, and mobility. Fe(II) is often found to co-exist with iron oxide minerals (IOMs) that are naturally occurring in soil and groundwater. However, the mechanism by which Cr(VI) is retained by IOMs in the presence of Fe(II) remains unclear. Ferrihydrite, the precursor of various iron oxides, is a representative IOM. In this study, the mechanism of Cr(VI) retention by ferrihydrite in the presence of Fe(II) was elucidated. Results from this study showed that Fe(II) adsorbed on ferrihydrite had a significant effect on the Cr(VI) retention process. FTIR analysis demonstrated that Cr(VI) adsorbed on a mineral surface, including outer-spheres and coordinated compounds, can be desorbed. XPS analysis further revealed that non-desorbable Cr includes reduced Cr(III) and partial Cr(VI), which were found to be incorporated into the Cr(III)-Fe(III) co-precipitation within the iron mineral. We also carried out XRD, HRTEM, and TG-DSC measurements in order to determine that the crystal structure, morphology, and physicochemical properties of IOMs were not changed significantly before and after Cr(VI) adsorption. The insights provided by this study aid in the development of a clear understanding of the effects of ferrihydrite in the presence of Fe(II) on the fate of Cr(VI) in both water and soil.
六价铬[Cr(VI)]污染因其高毒性、高溶解度和高迁移性而对环境构成重大危害。在土壤和地下水中，通常会发现铁(II)与铁氧化物矿物（IOM）共存。然而，在铁(II)存在的情况下，IOM 保留 Cr(VI)的机制仍不清楚。水铁矿是各种氧化铁的前体，是一种代表性的 IOM。在本研究中，阐明了铁(II)存在下水铁矿保留 Cr(VI)的机制。研究结果表明，吸附在水铁矿上的 Fe(II)对 Cr(VI)的保留过程有显著影响。FTIR 分析表明，吸附在矿物表面的 Cr(VI)，包括外配位和内配位化合物，可以被解吸。XPS 分析进一步表明，不可解吸的 Cr 包括还原态的 Cr(III)和部分 Cr(VI)，它们被发现嵌入到铁矿物中的 Cr(III)-Fe(III)共沉淀中。我们还进行了 XRD、HRTEM 和 TG-DSC 测量，以确定在 Cr(VI)吸附前后 IOM 的晶体结构、形态和物理化学性质没有发生显著变化。本研究的结果有助于更清楚地了解在水和土壤中，铁(II)存在下的水铁矿对 Cr(VI)命运的影响。
