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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。
The adsorption of acidic yellow 17 (AY17) on calcined hydrotalcite (Zn / Al-LDO) with a molar ratio of 3: 1 was studied. The effects of different initial concentrations of AY17 such as C0, temperature and p H on the adsorption of AY17 on Zn / Al-LDO were investigated. The kinetics and thermodynamics of the adsorption process were also discussed. The experimental results show that Zn / Al-LDO has a good removal effect on AY17. Under the condition of 25 ℃ and p H = 7, the optimum concentration of Zn / Al-LDO with 0.5 g? L? 1 is 50 ~ 200 mg? L? 1 AY17 removal rate of more than 98%. Kinetic and thermodynamic studies show that the adsorption of AY17 by Zn / Al-LDO is in accordance with the Langmuir and Freundlich adsorption isotherms and is a spontaneous and exothermic process. The adsorption free energy E calculated from the isothermal adsorption equation of D-R is 0.1474 ~ 1.6667 kJ? Mol? 1, indicating that the adsorption process is physical adsorption. At the same time, the adsorption process accords with quasi-secondary reaction kinetics model. Adsorption mechanism was further analyzed by XRD, FT-IR and intra-particle diffusion model. It is concluded that membrane diffusion and intragranular diffusion play a decisive role in the adsorption of AY17 by Zn / Al-LDO.