Colloidal fraction on pomelo peel-derived biochar plays a dual role as electron shuttle and adsorbent in controlling arsenic transformation in anoxic paddy soil

文献类型： 外文期刊

第一作者： Zhong, Ruilin

作者： Zhong, Ruilin;Pan, Dandan;Huang, Guoyong;Yang, Guang;Wang, Xiaonan;Niu, Rumiao;Ding, Ziman;Chi, Wenting;Li, Xiaomin;Pan, Dandan;Huang, Guoyong;Chi, Wenting;Wang, Ying;Cai, Xixi

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关键词： Biochar colloids; As(V) reduction; Electron transfer capability; As(III) immobilization; Adsorption

期刊名称：SCIENCE OF THE TOTAL ENVIRONMENT （ 影响因子：8.2； 五年影响因子：8.6 ）

ISSN： 0048-9697

年卷期： 2024 年 934 卷

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收录情况： SCI

摘要： Arsenic release and reduction in anoxic environments can be mitigated or facilitated by biochar amendment. However, the key fractions in biochars and how they control arsenic transformation remain poorly understood. In this study, a biochar produced from pomelo peel was rich in colloids and was used to evaluate the roles of the colloidal and residual fractions of biochar in arsenic transformation in anoxic paddy soil. Bulk biochar showed a markedly higher maximum adsorption capacity for As(III) at 1732 mg/kg than for As(V) at 75.7 mg/kg, mainly because of the colloidal fraction on the surface. When compared with the control and treatments with the colloidal/residual fraction, the addition of bulk biochar facilitated As(V) reduction and release in the soil during days 0 -12, but decreased the dissolved As(III) concentration during days 12 -20. The colloidal fraction revealed significantly higher electron donating capacity (8.26 mu mol e_ /g) than that of bulk biochar (0.88 mu mol e_ /g) and residual fraction (0.65 mu mol e _ /g), acting as electron shuttle to promote As(V) reduction. Because the colloidal fraction was rich in aliphatic carbon, fulvic acid-like compounds, potassium, and calcium, it favored As(III) adsorption when more As(III) was released, probably via organic-cation-As(III) complexation. These findings provide deeper insight into the role of the colloidal fraction of biochar in controlling anaerobic arsenic trans- formation, which will be helpful for the practical application of biochar in arsenic-contaminated environments.

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