纳米氧化铝吸附溶液中Cr(Ⅵ)的研究

Adsorption of Hexavalent Chromium by Nano-alumina Particles

采用共沉淀法制备了纳米氧化铝,所制备的氧化铝为γ型纳米氧化铝,颗粒直径在7~10nm,比表面积为117.986m2/g.以纳米氧化铝作为吸附剂,研究了纳米氧化铝对溶液中的Cr（Ⅵ）吸附特性,结果表明,纳米氧化铝的投加量为2g/L, Cr（Ⅵ）的初始质量浓度为15mg/l,初始pH2时吸附效果最好,在4h左右达到吸附平衡,去除率达96.1%.纳米氧化铝对溶液中的Cr（Ⅵ）的吸附动力学符合拟二级动力学模型,相关系数达0.945以上.吸附过程符合Freundlich等温方程,相关系数接近1.吸附过程是自发的放热过程,在低温条件下更有利于纳米氧化铝吸附溶液中的六价铬.

The alumina nanoparticles were synthesized by chemical precipitation process and characterized by BET, XRD and TEM. Results showed that the alumina nanoparticles were γ-alumina phase, the diameter of the particles and the specific surface area of alumina nanoparticles were between 7～10 nm and 117.986 m2/g, respectively. The adsorption characteristics of alumina nanoparticles were investigated. The results indicated that the removal efficiency of Cr（Ⅵ）can reach 96.1% when the initial pH value was 2, the dosage of alumina nanoparticles was 2g/L and Cr（Ⅵ）concentration was 15 mg/L within 4 hours. Results of kinetics showed that the adsorption of Cr（Ⅵ）by alumina nanoparticles could well described by the pseudo second order kinetic model （R2≥0.945）. Isotherm adsorption capacity of alumina nanoparticles can fit well to Freundlich equation. Additionally, the value of the correlation （R2） for the isotherm model was close to 1. It was found that the adsorption was the process of spontaneity and exotherm, and it was more effective for the removal of hexavalent chromium from aqueous solution at lower temperatures.