Adsorption of boron from aqueous solutions by activated carbon impregnated with salicylic acid: equilibrium, kinetic and thermodynamic studies

The adsorption of boron from aqueous solution containing boron by activated carbon impregnated with salicylic acid (ACISA) was studied in a batch system. In order to investigate the effect of initial boron concentration and temperature on boron adsorption capacity of ACISA; the equilibrium, kinetic and thermodynamic parameters were calculated. The adsorption capacity data were obtained by using Langmuir and Freundlich isotherm models and both models fitted well. The pseudo-first-order, pseudo-second-order and the intraparticle diffusion models were used to describe the kinetic parameters and the rate constants were evaluated. The experimental data fitted very well the pseudo-second-order kinetic model. The activation energy (E-a) calculated using the Arhenius equation was found to be 58.25 kJ mol(-1). Various thermodynamic parameters such as Gibbs free energy (Delta G degrees), enthalpy (Delta H degrees) and entropy (Delta S degrees) changes were computed and the results showed that the adsorption of boron onto ACISA was spontaneous and endothermic in nature.