A highly porous animal bone-derived char with a superiority of promoting nZVI for Cr(Ⅵ) sequestration in agricultural soils

作者：Kai Liu; Fangbai Li; Qingwen Tian; Chengrong Nie; Yibing Ma; Zhenlong Zhu; Liping Fang^*; Yuanying Huang; Siwen Liu

来源：Journal of Environmental Sciences, 2021, 104(06): 27-39.

• Bone char
• Nano zero-valent iron
• Adsorption
• Chromium
• Reduction

Paddy soil and irrigation water are commonly contaminated with hexavalent chromium [Cr(Ⅵ)] near urban industrial areas, thereby threatening the safety of agricultural products and human health. In this study, we develop a porous and high specific area bone char(BC) to support nanoscale zero-valent iron(n ZVI) and apply it to remediate Cr(Ⅵ) pollution in water and paddy soil under anaerobic conditions. The batch experiments reveal that BC/n ZVI exhibits a higher removal capacity of 516.7 mg/(g ·n ZVI) for Cr(Ⅵ) than n ZVI when normalized to the actual n ZVI content, which is 2.8 times that of n ZVI; moreover, the highest n ZVI utilization is the n ZVI loading of 15%(BC/n ZVI15). The Cr(Ⅵ) removal efficiency of BC/n ZVI15 decreases with increasing p H(4 – 10). Coexisting ions(phosphate and carbonate) and humic acid can inhibit the removal of Cr(Ⅵ) with BC/n ZVI15. Additionally, BC exhibits a strong advantage in promoting Cr(Ⅵ) removal by n ZVI compared to the widely used biochar and activated carbon. Our results demonstrate that reduction and coprecipitation are the dominant Cr(Ⅵ) removal mechanisms. Furthermore, BC/n ZVI15 shows a significantly higher reduction and removal efficiency as well as a strong anti-interference ability for Cr(Ⅵ) in paddy soil, as compared to n ZVI. These findings provide a new effective material for remediating Cr(Ⅵ) pollution from water and soil.