铁氧化物/活性炭对饮用水中Sb(V)的吸附性能及机理

采用液相沉积法制备了铁氧化物/活性炭复合材料(Fe₂O₃@AC)，通过单因素实验和正交实验优化了材料的制备条件，使用SEM、FTIR、XRD、XPS等分析方法对材料的形貌和性质进行了表征分析，通过吸附实验探究了Fe₂O₃@AC吸附除锑的效果及影响因素，并进一步对吸附除锑的机理进行了深入探讨。结果表明：最佳制备条件为纯水:乙醇:=4:1，Fe²⁺:Fe³⁺=1:1，总铁浓度为0.594 mol·L⁻¹，制备液pH=1.88。Fe₂O₃@AC吸附除锑的能力较其他金属基材料和活性炭有明显提高，锑原水质量浓度为38 μg·L⁻¹，Fe₂O₃@AC投加量为0.08 g·L⁻¹，吸附平衡后水中锑的去除率达97%，剩余锑质量浓度为1.06 μg·L⁻¹，满足国家饮用水卫生标准要求。微观表征显示铁氧化物颗粒成功负载于活性炭上，且铁氧化物晶体的结构完好。吸附反应符合准二级动力学和Langmuir等温模型，吸附反应以单层化学吸附为主，吸附类型为液膜扩散，颗粒内扩散，质量扩散的叠加形式。吸附方式为共沉淀，及溶解态锑与固相铁氧化物形成络合物，参与反应的官能团为—OH、—COOH、—Fe—OH、—Fe—O—Fe。

Adsorption performance and mechanism of iron oxide/activated carbon on Sb(V) in drinking water

The iron oxide/activated carbon composites(Fe2O3@AC) were prepared by liquid-phase deposition, and their preparation conditions were optimized by the single factor and orthogonal experiments. SEM, FTIR, XRD, XPS were used to characterize the morphology and properties. The adsorption experiments were conducted to investigate antimony removal effect by Fe2O3@AC adsorption and the corresponding influencing factors, and antimony removal mechanism was discussed in depth. The results showed that the optimal preparation conditions were following: pure water:ethanol of 4:1, Fe2+:Fe3+ of 1:1, total iron concentration of 0.594 mol·L−1 and the preparation solution pH of 1.88. Compared with other metal-based materials and activated carbon, The ability of antimony removal by Fe2O3@AC adsorption increased significantly. When the concentration of antimony in the raw water was 38 μg·L−1 and Fe2O3@AC dosage was 0.08 g·L−1, the removal rate of antimony could reach 97% after adsorption equilibrium, and the remaining antimony concentration was 1.06 μg·L−1, which met the requirements of National Drinking Water Sanitation Standards. Microscopic characterization showed that the iron oxide particles were successfully loaded on the activated carbon and the iron oxide crystals were structurally intact. The adsorption reaction conformed to the quasi-secondary kinetic and Langmuir isotherm models, and the adsorption reaction was dominated by monolayer chemisorption. The adsorption types were superposition of liquid film diffusion, intraparticle diffusion and mass diffusion forms. The adsorption was co-precipitated and complexes were formed between dissolved antimony and solid phase iron oxides, the functional groups involved in the reaction were —OH,—COOH,—Fe—OH,—Fe—O—Fe.