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- Title
Hexavalent Chromium Detoxification by Biochars: Influences of Organic and Inorganic Electron Donors.
- Authors
Ye, Zhuofeng; Fei, Ying-heng; Li, Manzhi; Guan, Jieyang; Huang, Zhenhong; Tan, Zhenwei; Xiao, Tangfu
- Abstract
Previous studies proved that biochar provides potential solutions for hexavalent chromium (Cr(VI)) detoxification. However, the roles of inorganic constituents in addition to the organic carbon matrix still need to be verified. Besides, the interferences with environmental electron donors, including organic reductants like low molecular weight organic acids (LMWOAs) and inorganic reductants like Fe2+, also needs to be clearly elucidated. In this study, two typical kinds of biochar were compared for their performances and mechanisms in removing Cr(VI). The responses to exogenous electron donors were also examined. The removal of Cr(VI) by the biochar derived from maize straw, which had fewer inorganic content (Fe content < 0.1%, at%), was largely associated with the activity of the organic groups and the amount of persistent free radicals. While for the biochar derived from Fe-rich sludge (Fe content > 1%, at%), the Cr(VI) reduction was predominately contributed by the inorganic reducing component, i.e. Fe-containing fractions. For the exogenous reductants, the organic reductant LMWOAs (removal rate improved from 41 to 62% (p < 0.01)) were relative weaker than the inorganic reductant Fe2+ (removal rate improved to 76% (p < 0.01)). The better reduction by Fe than the organic molecules could be mainly contributed to the redox activity as well as the improved electron cycling with the biochar matrix. Besides, the precipitated Fe(III) after redox reaction on the biochar could further enhance the adsorption of Cr(VI) and reinforce the immobilization of Cr(III). These findings would help to develop highly cost-effective Fe-modified biochar based strategies for Cr(VI) detoxification.Highlights: MBC with few ashes is more dependent on the organic functional groups. Endogenous Fe in ash-rich SBC plays crucial roles in Cr(VI) removal. LMWOAs enhance the reduction but hinder the adsorption. Exogenous Fe2+ largely improves the reduction and reinforces the immobilization.
- Publication
International Journal of Environmental Research, 2024, Vol 18, Issue 4, p1
- ISSN
1735-6865
- Publication type
Article
- DOI
10.1007/s41742-024-00623-4