Adsorption of acid yellow 17 with calcined Zn/Al layered double hydroxides

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 pH 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 pH=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 kJ·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. ©, 2015, Zhejiang University. All right reserved.