酸性黄17在焙烧态Zn/Al水滑石上的吸附研究

Adsorption of Acid Yellow 17 with Calcined Zn/Al Layered Double Hydroxides

研究了摩尔比为3：1的焙烧态水滑石（Zn/Al-LDO）对酸性黄17（AY17）的吸附。考察了AY17不同起始浓度C0、温度及p H值等因素对Zn/Al-LDO吸附AY17的影响,并探讨了吸附过程的动力学和热力学规律。实验结果表明：Zn/Al-LDO对AY17具有良好的去除效果,在25℃、p H=7条件下,0.5 g·L^-1的Zn/Al-LDO对C0=50~200 mg·L^-1的AY17去除率超过98%。动力学和热力学研究表明：Zn/Al-LDO对AY17的吸附过程均符合Langmuir和Freundlich等温吸附方程,且是一个自发、放热的过程。由D–R等温吸附方程计算的吸附自由能E为0.1474~1.6667 k J·mol^-1,表明吸附过程为物理吸附。同时,该吸附过程符合准二级反应动力学模型。通过XRD、FT-IR及颗粒内扩散模型的实验数据进一步分析吸附机理,推断膜扩散和颗粒内扩散对Zn/Al-LDO吸附AY17起决定性作用。

Adsorption of Acid Yellow 17（AY17） with calcined Zn/Al layered double hydroxides（Zn/Al-LDO）（Zn/Al = 3：1, molar ratio） was investigated. The effects of AY17 initial concentration（C0）, temperature and p H value were studied, and adsorption isotherms and thermodynamic functions were calculated. More than 98% of AY17 was absorbed by 0.5 g·L^-1 Zn/Al-LDO under conditions of C0 = 50~200 mg？L？1, 25℃ and p H = 7. Adsorption isotherms and kinetic results show that the adsorption process can be well fitted with Langmuir and Freundlich equations, and the process is spontaneous and exothermic. The adsorption free energy values（E = 0.1474~1.6667 k J·mol^-1） derived from the D-R model indicate that the adsorption is dominated by physical processes. Three models were used to fit the kinetics experimental data, and it was found that the pseudo-second-order kinetics model was better to describe the uptake process. Based on the results of XRD, FT-IR and intraparticle diffusion model, it is assumed that film diffusion and intraparticle diffusion play important roles in the adsorption process.