离子交换树脂吸附铬(Ⅵ)的热力学和动力学研究

Study on sorption thermodynamics and kinetics of Cr(Ⅵ) on ion-exchange resin

采用静态吸附法,研究用201×7阴离子交换树脂吸附Cr(Ⅵ)的过程和机理。结果表明,在一定的浓度范围内,201×7阴离子交换树脂对Cr(Ⅵ)的吸附符合Langmuir和Freundlich吸附等温线,以离子交换吸附为主,但Langmuir方程更能准确反映该交换吸附过程。测得热力学参数△H=4.182 kJ/mol,△S=34.80 J/(mol.K),△G=-6.195 kJ/mol。动力学研究表明,该树脂吸附Cr(Ⅵ)受颗粒扩散控制,铬的吸附速率常数为k=3.25×10-4s-1,内扩散系数随溶液pH值的增大而减小。

The sorption process of Cr （ Ⅵ ） on 201×7 anion exchange resin has been investigated by the method of static adsorption in this paper. The results showed that within the experiment range of the Cr （Ⅵ） concentration,the sorption of Cr （Ⅵ） on 201 × anion exchange resin agreed well with the Lang- muir and the Freundlich isothermal sorption equation. The Langmuir gave the better-fit to the experiment data. The sorption parameters of thermodynamic were △H = 4. 182 kJ/mol, △S = 341 80 J/（mol · k） , △ G = -6. 195 kJ/mol respectively. The adsorption was controlled by pore diffusion,and the adsorption rate constant of Cr （ Ⅵ ） was 3.25 × 10 -4 s-1. The internal diffusion coefficient decreased with the in- crease of solution pH.