Graduate Institute of Environmental Engineering, National Taiwan University, No. 1, Sec. 4. Roosevelt Rd., Taipei, 10617, Taiwan; Faculty of Environmental Engineering, National University of Civil Engineering, 55 Giai Phong, Hai Ba Trung, Hanoi 100000, Vietnam.
Graduate Institute of Environmental Engineering, National Taiwan University, No. 1, Sec. 4. Roosevelt Rd., Taipei, 10617, Taiwan.
Water Res. 2021 Jan 1;188:116495. doi: 10.1016/j.watres.2020.116495. Epub 2020 Oct 5.
In the present work, an active MnO2/rice husk biochar (BC) composite (MBC) was prepared to enhance As(III) removal for groundwater remediation. The MBC material obtained an improved porous structure (i.e., specific surface area, pore volume and mesoporosity) with MnO, providing abundant reaction or interaction sites for surface or interface-related processes such as redox transformation and adsorption of arsenic. As a result, a significant enhancement in arsenic removal can be achieved by using MBC. More specifically, MBC showed a high removal capacity for As(III), which was tenfold higher than that of BC. This improvement can be ascribed to the redox transformation of As(III) via MnO, resulting in the more effective removal of As(V) species. In addition, pH was an important factor that could influence the As(III) removal capacity. Under alkaline conditions, the As(III, V) removal capacity of MBC was clearly lower than those under acidic and neutral conditions due to the negative effects of electrostatic repulsion. Importantly, a powerful transformation capability of As(III) via MBC was presented; namely, only 5.9% As(III) remained in solution under neutral conditions. Both MnO and the BC substrate contributed to the removal of arsenic by MBC. MnO delivered Mn-OH functional groups to generate surface complexes with As(V) produced by As(III) oxidation, while the reduced Mn(II) and As(V) could precipitate on the MBC surface. The BC substrate also provided COOH and OH functional groups for As(III, V) removal by a surface complexation mechanism. Note that the application of MBC in the treatment of simulated groundwater demonstrated an efficient arsenic removal of 94.6% and a concentration of arsenic as low as the 10 µg L WHO guideline.
在本工作中，制备了一种活性 MnO2/稻壳生物炭（BC）复合材料（MBC），以增强地下水修复中 As(III)的去除。所得 MBC 材料具有改进的多孔结构（即比表面积、孔体积和中孔性）和 MnO，为表面或界面相关过程（如氧化还原转化和砷的吸附）提供了丰富的反应或相互作用位点。结果，MBC 可显著增强砷的去除。具体而言，MBC 对 As(III)表现出高去除能力，是 BC 的 10 倍。这种改善可归因于 MnO 对 As(III)的氧化还原转化，从而更有效地去除 As(V)物种。此外，pH 是影响 As(III)去除能力的重要因素。在碱性条件下，由于静电排斥的负面影响，MBC 的 As(III、V)去除能力明显低于酸性和中性条件。重要的是，MBC 表现出强大的 As(III)转化能力；即在中性条件下，只有 5.9%的 As(III)留在溶液中。MnO 和 BC 基质都有助于 MBC 去除砷。MnO 提供 Mn-OH 官能团，与 As(III)氧化生成的 As(V)生成表面配合物，而还原的 Mn(II)和 As(V)可沉淀在 MBC 表面。BC 基质还通过表面络合机制提供 COOH 和 OH 官能团，用于去除 As(III、V)。值得注意的是，MBC 在模拟地下水处理中的应用实现了 94.6%的高效砷去除和低至 10 µg L WHO 指南的砷浓度。
