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| Titanium dioxide loaded biochar alleviates arsenite release during facilitating microbial reduction of arsenitebearing ferrihydrite |
| Received:March 02, 2025 |
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| KeyWord:biochar;titanium dioxide;arsenic;ferrihydrite;electron shuttle;anaerobic |
| Author Name | Affiliation | E-mail | | ZHU Zhiyuan | School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou 215009, China
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 211135, China | | | WU Song | State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 211135, China | songwu@issas.ac.cn | | GUO Ruizhi | School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China | | | SHI Weilin | School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou 215009, China | | | WANG Yujun | State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 211135, China
University of Chinese Academy of Sciences, Beijing 100049, China | |
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| Abstract: |
| Remediation of arsenic-contaminated paddy soils gained numerous scientific attentions in agronomic and environmental studies. Biochar was widely applied for paddy soil pollution remediation, carbon sequestration, and fertility enhancement. However, redox-active biochar can act as an electron shuttle to accelerate the reductive dissolution of arsenite As（Ⅲ）-bearing iron mineral, which exacerbate the environmental risk of arsenic. In this study, modelling iron-reducing, sulfate-reducing, and methanogenesis conditions were constructed by inoculating microbial pure culture or acclimated mix culture. The efficacy of titanium dioxide（TiO2）-loaded biochar immobilizing soluble and ferrihydrite immobilized As（Ⅲ）under these conditions were investigated. TiO2-loaded biochars prepared at 400-700 ℃ exhibited As （Ⅲ）adsorption capacities of 1.35-1.73 mg·g-1 under aerobic conditions. The shift redox environment to iron-reducing, sulfate-reducing, and methanogenesis conditions led to the successive attenuation of As（Ⅲ）adsorption capacity, with 39.4%-70.4% of the capacity was retained. During TiO2-loaded biochars mediating microbial reduction of As（Ⅲ）-bearing ferrihydrite, loading of TiO2 reduced the electron shuttling efficiency as compared to pristine biochars（0.207-0.542 mmol·h-1 vs. 0.301-0.918 mmol·h-1）, but promoted the precipitation of siderite. More importantly, loading of TiO2 on biochars effectively reduced both the rate and extent of As（Ⅲ）release during ferrihydrite reduction. The immobilization of As（Ⅲ）by loading TiO2 on biochars presents a novel strategy to reduce environmental risk of As（Ⅲ） under reducing environment, promoting the application of TiO2-loaded biochar for remediation of arsenic-contaminated paddy soil. |
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