School of Environmental Studies & State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Rd., Wuhan, Hubei 430074, PR China.
Department of Earth and Environmental Sciences, University of Waterloo, 200 University Ave. W., Waterloo, ON N2L 3G1, Canada.
Bioresour Technol. 2020 May;304:122978. doi: 10.1016/j.biortech.2020.122978. Epub 2020 Feb 11.
Batch experiments followed by solid-phase analyses were conducted to explore As(III) and As(V) removal mechanisms by Fe-modified biochars (FeBC) pyrolyzed at different temperatures (300, 600, and 900 °C). Arsenic removal by FeBC, best described by pseudo-second order kinetic and Langmuir isotherm models, increased from 73.8 to 99.9% for As(III) and 86.8 to 99.9% for As(V) as the pyrolysis temperature increased. The addition of calcite enhanced the removal efficiency (all > 99%). Confocal micro-X-ray fluorescence imaging (CMXRFI) analyses indicated As co-located with Fe and diffused deeper into the particles as the pyrolysis temperature increased. For As(III)-spiked systems, X-ray absorption near-edge structure (XANES) data indicated 20.2 to 81.5% of As(III) was oxidized to As(V) as the pyrolysis temperature increased; an increase of oxidation efficiency was observed after adding calcite. For As(V)-spiked systems, no As(V) reduction was observed. Overall, As(III/V) removal using FeBC was affected by the spatial distribution and species of As.
采用批实验结合固相分析的方法，研究了不同温度（300、600 和 900°C）下制备的铁改性生物炭（FeBC）去除 As(III)和 As(V)的机制。FeBC 对 As(III)和 As(V)的去除率分别由 73.8%增加到 99.9%和由 86.8%增加到 99.9%，对 As 的去除效果最好的模型为拟二级动力学模型和 Langmuir 等温模型，这表明随着热解温度的升高，去除效果增强。方解石的添加提高了去除效率（均>99%）。共焦微 X 射线荧光成像（CMXRFI）分析表明，随着热解温度的升高，As 与 Fe 共定位并向颗粒内部扩散。对于 As(III)污染体系，X 射线吸收近边结构（XANES）数据表明，随着热解温度的升高，20.2%至 81.5%的 As(III)被氧化为 As(V)；添加方解石后，氧化效率增加。对于 As(V)污染体系，未观察到 As(V)的还原。总体而言，FeBC 对 As(III/V)的去除受到 As 的空间分布和形态的影响。
