活性氧化铝对As(Ⅲ)和As(Ⅴ)的吸附性能研究

Adsorption Behavior of As(Ⅲ) and As(Ⅴ) by Activated Aluminum

采用静态吸附试验方法,研究了活性氧化铝对As(Ⅲ)和As(Ⅴ)的吸附特性和机制。结果表明,活性氧化铝对As(Ⅲ)和As(Ⅴ)的吸附特性一致:室温条件下,吸附平衡时间约为24h,动力学符合拟一级动力学模型,Boyd动力学模型说明液膜扩散是吸附反应速率的控制因素;与Freundlich等温线模型相比,Langmuir模型能够很好地描述吸附行为,说明以单分子层吸附为主;经过Dubinin-Radushkevich模型计算出的平均吸附自由能小于8kJ·mol-1,表明吸附为物理过程;热力学参数表明吸附为自发、吸热、熵增加的过程,在吸附过程中,固液界面的无序度增加。

Batch experiments were carried out in order to investigate the adsorption behavior of As （ Ⅲ ） and As （ Ⅴ） affected by activated aluminum. The results show that the adsorption characteristics of As （ Ⅲ ） and As （Ⅴ） are consistent. 24-hour is enough to obtain equilibrium; The kinetic data correlates well with the pseudo-first-order model; the film diffusion is the rate-limiting step approved by Boyd kinetic model; Compared with the Freundlich model, Langmuir isotherm model offers a better explanation for the adsorption of arsenic onto activated aluminum, indicating the adsorption is mainly monolayer; The obtained mean adsorption energy values calculated from Dubinin-Radushkevich model are lower than 8 kJomo1-1 , suggesting the adsorption process is physical; The thermodynamic parameters point out that the adsorption is a spontaneous, endothermic process, and the randomness increase at the solid-liquid interface after adsorption.