Adsorption of atenolol on kaolinite

Abstract

In this study the adsorption of atenolol (AT), a β-blocker, on kaolinite, a clay mineral of low surface charge, was investigated under varying initial AT concentration, equilibrium time, solution pH, ionic strength, and temperature conditions. The results showed that the amounts of AT uptake by kaolinite were close to its cation exchange capacity value and the AT adsorption was almost instantaneous, suggesting a surface adsorption. The adsorption was exothermic and the free energy of adsorption was small negative, indicating physical adsorption. The increase in ionic strength of the solution drastically reduced AT uptake on kaolinite. A significant reduction in AT uptake was found at solution pH below 5 or above 10. The FTIR results showed band shifting and disappearance for NH bending vibration and benzene ring skeletal vibration at 3360 and 1515 cm-1 and band splitting at 1412 and 1240 cm-1 attributed to C-N valence vibration coupled with NH bending vibrations and alkyl aryl ether linkage, suggesting the participation of NH, -O-, and benzene ring for AT adsorption on kaolinite.