Hexavalent chromium transformation during transport of L − cysteine modified nano − zero − valent iron supported by biochar via green synthesis in water and soil systems
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引用次数: 0
Abstract
Purpose
The Cr(VI) removal capacity of green synthesized nano-zero-valent iron (GnZVI) using tea polyphenols (TPs) remains limited. To improve their application in contaminated soil and groundwater, the GnZVI was modified. This is necessary for in-situ remediation of heavy metal-contaminated soil and groundwater.
Materials and methods
The GnZVI-based carbon-composite (L&GnZVI@BC) was successfully constructed via the synergistic effect of L-cysteine modification and biochar support. The Cr(VI) removal capacity and transportability of L&GnZVI@BC were investigated in soil–water system by batch and column experiments.
Results and discussion
Comparison with two materials of GnZVI separately modified by L-cysteine (L-GnZVI) or supported by biochar (GnZVI@BC)), GnZVI composite with a combination modification of L-cysteine and biochar (L&GnZVI@BC, L-cysteine/biochar/Fe = 0.1/0.1/1) showed a much higher Cr(VI) removal capacity in soil and groundwater. The synergistic effect of the reduction of L-cysteine functional groups and the dispersibility of biochar support can enhance the transportability of L&GnZVI@BC in water-saturated sand media for more Cr(VI) adsorption at neutral pH; while that improved the soluble Fe(II) released from composite for the higher reduction of Cr(VI) into Cr(III) at acidic pH. Particularly, L&GnZVI@BC favored more Cr(III) generation during transport in porous media at lower pH when applied in the treatment of Cr(VI) contamination.
Conclusion
This research highlights that the modification of both L-cysteine and biochar was beneficial to sufficient transport and efficient remediation in Cr(VI)-contaminated soil and groundwater environments at different pH ranges. This study’s results provide a theoretical support for the practical application of nZVI composites in in-situ remediation of Cr(VI)-contaminated soil and groundwater via an environmental-friendly approach.
期刊介绍：
The Journal of Soils and Sediments (JSS) is devoted to soils and sediments; it deals with contaminated, intact and disturbed soils and sediments. JSS explores both the common aspects and the differences between these two environmental compartments. Inter-linkages at the catchment scale and with the Earth’s system (inter-compartment) are an important topic in JSS. The range of research coverage includes the effects of disturbances and contamination; research, strategies and technologies for prediction, prevention, and protection; identification and characterization; treatment, remediation and reuse; risk assessment and management; creation and implementation of quality standards; international regulation and legislation.
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