School of Environmental Studies & State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China.
School of Environmental Studies & State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China; Chongqing Nanjiang Engineering Survey and Design Group Co., Ltd., Chongqing 401147, China.
Bioresour Technol. 2021 Nov;340:125674. doi: 10.1016/j.biortech.2021.125674. Epub 2021 Jul 29.
The Fe-modified biochar (FeBC) was used to remove aqueous As(III/V), and the role of oxygen (O) in As removal was investigated by integrating aqueous and solid analyses. The removal efficiencies for As(III) and As(V) increased from 86.4% and 99.2% under anoxic conditions, respectively, to >99.9% when O was available. FeBC removed As(III) from As(III)-spiked systems by surface-oxidation following adsorption, where oxidation of As(III) was promoted by O. As(V) was first reduced, re-oxidized in solutions, and then adsorbed to FeBC in As(V)-spiked systems, where reduction of As(V) was inhibited at the presence of O. Both As(III) and As(V) were bidentate corner-sharing complexed to Fe oxides/hydroxides on FeBC, with As coordinated to Fe at ~3.4 Å according to As extended X-ray absorption fine structure (EXAFS) modeling. These findings identified the effect of ambient O in As(III/V) redox transformations and removal, guiding the further application of FeBC in environmental treatment.
Fe 改性生物炭 (FeBC) 被用于去除水溶液中的 As(III/V)，通过整合水相和固相分析，研究了氧 (O) 在 As 去除中的作用。在缺氧条件下，As(III)和 As(V)的去除效率分别从 86.4%和 99.2%提高到有 O 存在时的 >99.9%。FeBC 通过吸附后的表面氧化去除 As(III)-加标体系中的 As(III)，其中 O 促进了 As(III)的氧化。在 As(V)-加标体系中，As(V)首先被还原，在溶液中重新氧化，然后被吸附到 FeBC 上，其中 O 的存在抑制了 As(V)的还原。根据砷扩展 X 射线吸收精细结构 (EXAFS) 建模，As(III)和 As(V)都与 FeBC 上的 Fe 氧化物/氢氧化物形成双齿顶角共享配合物，As 与 Fe 的配位距离约为 3.4 Å。这些发现确定了环境 O 对 As(III/V)氧化还原转化和去除的影响，指导了 FeBC 在环境处理中的进一步应用。
