State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China.
School of Environment and Resources, Shanxi University, Taiyuan 030006, China.
Bioresour Technol. 2018 Aug;261:142-150. doi: 10.1016/j.biortech.2018.04.004. Epub 2018 Apr 5.
Willow residue biochar (BC) and modified biochars (hydrochloric acid washing (HBC), HBC loaded with nanoscale zero-valent iron (nZVI-HBC), and HBC loaded with ferric iron (Fe-HBC)) after aging were used for aqueous Cr(VI) removal. HBC (>98.67%), nZVI-HBC (>98.86%), and Fe-HBC (>99.64%) kept high Cr(VI) removal rates under the acidic conditions within a wide pH range (<7.0), indicating their good adaptability to pH change because of aging. Cr(VI) reduction to Cr(III) was the dominant removal mechanism. The formation of COOH on BC, HBC, and nZVI-HBC indicates the oxidation of surface functional groups by Cr(VI) and simultaneous Cr(VI) reduction. The disappearance of nZVI peaks indicates the reduction of Cr(VI) to Cr(III) by nZVI. The color reaction result demonstrated that the converted Fe in Fe-HBC contributed to Cr(VI) reduction. Taking into account the removal efficiency, recyclability, cost, preparation process, and stability of adsorbents, Fe-HBC was recommended for Cr(VI) removal.
柳树残渣生物炭 (BC) 和改性生物炭 (盐酸洗涤 (HBC)、负载纳米零价铁的 HBC (nZVI-HBC) 和负载三价铁的 HBC (Fe-HBC)) 老化后用于去除水溶液中的六价铬。在较宽的 pH 范围内 (<7.0)，HBC (>98.67%)、nZVI-HBC (>98.86%) 和 Fe-HBC (>99.64%) 在酸性条件下保持高的六价铬去除率，这表明它们对 pH 变化有很好的适应性，这是因为老化。六价铬还原为三价铬是主要的去除机制。BC、HBC 和 nZVI-HBC 表面羧酸基团的形成表明表面官能团被 Cr(VI)氧化，同时 Cr(VI)被还原。nZVI 峰的消失表明 nZVI 将 Cr(VI)还原为 Cr(III)。显色反应结果表明，Fe-HBC 中转化的 Fe 有助于 Cr(VI)的还原。考虑到去除效率、可回收性、成本、制备过程和吸附剂的稳定性，建议使用 Fe-HBC 去除 Cr(VI)。
