Thermodynamic of adsorption of indium on strong acidic cationic exchange fiber

Adsorption of In³⁺ from aqueous solution by strong acid cationic exchange fiber (SACEF) was studied using batch experiments. Langmuir, Dubinin-Radushkevich (D-R), Freundlich, Temkin, Redlich-Peterson (R-P) and Koble-Corrigan (K-C) models were applied to analyze the adsorption equilibrium data of In³⁺ on SACEF obtained with researching range of concentration at 293-323 K through linear fitting and nonlinear fitting methods. The results show that, except for Langmuir nonlinear fitting and Dubini-Radushkevieh models, the adsorption equilibrium data can be well interpreted by both the linear fitting and nonlinear fitting of the models with the R² values about 0.9. Out of all the models, Langmuir linear fitting model is the suitable model with highest linear fitting R² value. The value of isosteric enthalpy indicates that the endothermic nature of the adsorption of In³⁺ on SACEF. The adsorption of In³⁺ on SACEF is an endothermic, spontaneous and entropy increase process with ΔH>0 and reasonable explanation is given to the adsorption behavior.