School of Energy and Civil Engineering, Harbin University of Commerce, Harbin, 150028, China.
Department of Nephropathy, First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, 150001, China.
Chemosphere. 2020 Jul;250:126275. doi: 10.1016/j.chemosphere.2020.126275. Epub 2020 Feb 21.
Innovative iron/calcium in-situ-impregnated mesoporous activated carbons (GL100 and GL200) have been prepared by iron/calcium in-situ-impregnation and Multistage Depth-Activation. Arsenic adsorption kinetics, isotherms, thermodynamics, and re-usability were investigated. Effects of surface-absorbed (ST-HA) and dissolved states humic acid (DHA) on the arsenic adsorption were also determined. Results suggested in-situ iron/calcium impregnation caused the well-development of mesoporous structures during ranges of 2.0-5.0 nm in GL100 and 5.0-50 nm in GL200, respectively. The increase of iron/calcium ensured surface basicity and high ash contents on GL100/GL200, and As(III)/As(V) can be better adsorbed in neutral conditions with higher kinetics in comparison with regular mesoporous carbon XHIT. Maximum adsorption capacities of As(III)/As(V) by GL100 and GL200 were 2.985/3.385 mg/g and 2.516/2.807 mg/g, respectively. Arsenic desorption and carbon re-usability of GL100/200 was improved. As(III)(As (V)) adsorption capacities by GL100 and GL200 were 2.437(1.672) mg/g and 1.740(1.308) mg/g, respectively, after eight cycles. Arsenic adsorption capacities on GL100 were proved to be promoted with the presence of low-level of ST-HA or DHA, and be inhibited at a high-level. As(V) was bound more strongly than As(III) in the presence of ST-HA. As(III)/As(V) uptakes increased slightly and decrease gradually to 1.75/1.86 mg/g in the presence of DHA (0-10 mg DOC/L). Physisorption and chemisorption mechanisms dominant in arsenic adsorption on GL100 in presence of humic acid, forming inner-sphere complexation with metallic oxide, functional groups on carbon surface and humic acid structure, or ternary surface complexation via cationic metal ions as cation bridge.
创新性的铁/钙原位浸渍介孔活性炭 (GL100 和 GL200) 是通过铁/钙原位浸渍和多阶段深度活化制备的。研究了砷的吸附动力学、等温线、热力学和可重复使用性。还确定了表面吸附 (ST-HA) 和溶解态腐殖酸 (DHA) 对砷吸附的影响。结果表明，原位铁/钙浸渍在 GL100 的 2.0-5.0nm 和 GL200 的 5.0-50nm 范围内分别导致介孔结构的良好发展。铁/钙的增加确保了 GL100/GL200 的表面碱性和高灰分含量，与常规介孔碳 XHIT 相比，在中性条件下可以更好地吸附 As(III)/As(V)，并且动力学更高。GL100 和 GL200 对 As(III)/As(V)的最大吸附容量分别为 2.985/3.385mg/g 和 2.516/2.807mg/g。GL100/200 的砷解吸和碳可重复使用性得到了提高。GL100 和 GL200 经过八次循环后，As(III)(As(V))的吸附容量分别为 2.437(1.672)mg/g 和 1.740(1.308)mg/g。研究表明，低水平的 ST-HA 或 DHA 存在会促进 GL100 上的砷吸附，而高水平的 ST-HA 或 DHA 存在则会抑制砷的吸附。在 ST-HA 存在下，As(V)比 As(III)结合得更牢固。在 DHA(0-10mgDOC/L)存在下，As(III)/As(V)的摄取量略有增加，然后逐渐下降至 1.75/1.86mg/g。在腐殖酸存在下，GL100 上砷的吸附主要通过物理吸附和化学吸附机制，形成金属氧化物、碳表面官能团和腐殖酸结构内的内球络合，或通过阳离子金属离子作为阳离子桥的三元表面络合。
