Adsorption Kinetics and Thermodynamics of Salicylic Acid on D201 Resin

The adsorption kinetics and thermodynamics behavior of salicylic acid in aqueous solution on D201 macroreticular anion exchange resin were investigated.Experimental results show that the maximum adsorption ability of D201 resin occurs at pH= 3~12.The adsorption behavior of D201 resin for salicylic acid obeys the Freundlich isotherm.At temperature of 298~318 K and the adsorption of salicylic acid of 100～120 mg/g,the adsorption enthalpy ΔH of-7.38～-5.00 kJ/mol,the free energy ΔG of-8.46～-9.37 kJ/mol and the entropy of adsorption ΔS of 3.62～13.74 J/(K·mol) were obserred.The adsorption kinetics data well fit the Lagergren pseudo-first order rate equation.The adsorption rate constants are 0.0472～0.124/min and the adsorption activity energy is 38.1 kJ/mol.Besides the intra-particle diffusion,other processes such as film diffusion also simultaneously affects the rate of adsorption.Up to 99% of the salicylic acid adsorbed in the resin can be easily and quickly eluted with a 5%NaCl+2%NaOH solution at 303 K.