Adsorption of dispersed red from aqueous solution onto calcined layered double hydroxides: equilibrium, kinetics studies

作者：Wang, Yulin; Li, Jianguang; Lv, Liang^*; Xv, Guoyun; Wu, Yuechao; Chen, Jianjun; Hu, Wei^*

来源：Desalination and Water Treatment, 2016, 57(40): 18879-18887.

DOI：10.1080/19443994.2015.1093324

• Layered double hydroxides
• Calcined
• Removal
• Dispersed red
• Dye

Calcined layered double hydroxides (CLDHs) were used as an adsorbent to remove an azo dyedispersed red (DR), from aqueous solution by the batch adsorption technique. Various conditions were evaluated, including CLDH structures, adsorbent dosage, initial dye concentration, and temperature. It was found that the layered double hydroxides with a Mg/Al ratio of 3 calcined at 500 degrees C had the highest capacity for adsorption of DR. The adsorption capacity of CLDH decreased with increasing adsorbent dose, but increased with increasing initial DR concentration. The data of sorption isotherms fitted well into the Langmuir equation. Thermodynamic parameters such as G degrees, H degrees, and S degrees were calculated. The negative values of G degrees indicate the spontaneous nature of adsorption of DR. The positive value of H degrees confirms the endothermic nature of the removal process. The positive value of S degrees suggests the increased randomness at the solid/solution interface for the adsorption of DR onto CLDHs. The results of two kinetic models which fitted the experimental data show that the pseudo-first-order kinetic model gave a better description for the adsorption process. The rate constants and activation energy of adsorption were also calculated. The calculated value of E-a was 14.50kJ/mol, which indicates that the adsorption process was controlled by diffusion.

• 出版日期2016
• 单位衢州学院