Effect of Mn(II) and Phytic Acid on Cr(VI) in the Ferrihydrite-Cr(VI) Co-precipitates: Implication for the Migration Behavior of Cr(VI)

Sun, Guangzhao; Chrysikopoulos, Constantinos V.; Fu, Fenglian

doi:10.1021/acsestwater.2c00014

Cited by 2 publications

(2 citation statements)

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“…Cell densities were determined to obtain suitable Fe mineral transformation and Cr(VI) reduction rates, which allowed the exploration of biological and chemical reactions. It has been reported that Cr/Fe ratios of 2 × 10 –3 , 4 × 10 –3 , and 8 × 10 –3 in this study are typical concentrations in Cr-contaminated soil environments and do not remarkably impede ferrihydrite transformation . The initial FA concentration was a representative concentration of OM in soil solutions .…”

Section: Methodssupporting

confidence: 53%

“…It has been reported that Cr/Fe ratios of 2 × 10 −3 , 4 × 10 −3 , and 8 × 10 −3 in this study are typical concentrations in Crcontaminated soil environments 24 and do not remarkably impede ferrihydrite transformation. 46 The initial FA concentration was a representative concentration of OM in soil solutions. 3 Detailed properties of the synthesized coprecipitates are provided in Table S1 and Figure S1 of the Supporting Information.…”

Section: Incubation Experimentsmentioning

confidence: 99%

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Reductive Sequestration of Cr(VI) and Immobilization of C during the Microbially Mediated Transformation of Ferrihydrite-Cr(VI)-Fulvic Acid Coprecipitates

Zhang

Yang

et al. 2023

Environ. Sci. Technol.

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Cr(VI) detoxification and organic matter (OM) stabilization are usually influenced by the biological transformation of iron (Fe) minerals; however, the underlying mechanisms of metal-reducing bacteria on the coupled kinetics of Fe minerals, Cr, and OM remain unclear. Here, the reductive sequestration of Cr(VI) and immobilization of fulvic acid (FA) during the microbially mediated phase transformation of ferrihydrite with varying Cr/Fe ratios were investigated. No phase transformation occurred until Cr(VI) was completely reduced, and the ferrihydrite transformation rate decreased as the Cr/Fe ratio increased. Microscopic analysis was uncovered, which revealed that the resulting Cr(III) was incorporated into the lattice structure of magnetite and goethite, whereas OM was mainly adsorbed on goethite and magnetite surfaces and located within pore spaces. Fine line scan profiles showed that OM adsorbed on the Fe mineral surface had a lower oxidation state than that within nanopores, and C adsorbed on the magnetite surface had the highest oxidation state. During reductive transformation, the immobilization of FA by Fe minerals was predominantly via surface complexation, and OM with highly aromatic and unsaturated structures and low H/C ratios was easily adsorbed by Fe minerals or decomposed by bacteria, whereas Cr/Fe ratios had little effect on the binding of Fe minerals and OM and the variations in OM components. Owing to the inhibition of crystalline Fe minerals and nanopore formation in the presence of Cr, Cr sequestration and C immobilization can be synchronously favored at low Cr/Fe ratios. These findings provide a profound theoretical basis for Cr detoxification and synchronous sequestration of Cr and C in anoxic soils and sediments.

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Section: Methodssupporting

confidence: 53%