In this study the adsorption of atenolol (AT), aβ-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−1and band splitting at 1412 and 1240 cm−1attributed 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.

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Talc is commonly used as an excipient for drug formulations. The general expectation is that the excipient should have only minimal interactions with the carrying drug. In this study, the adsorption of atenolol (AT), a β-blocker, on talc, a clay mineral of pH-dependent surface charge, was evaluated under different physicochemical conditions such as the initial AT concentration, equilibrium time, solution pH, ionic strength and temperature. Our experiments showed that talc had an AT adsorption capacity of 11 mmol/kg. In addition, adsorption of AT on talc was instantaneous, which suggests that the adsorption sites were located on the external surfaces or edges. Factors such as solution pH, ionic strength and temperature all had minimal influence on AT adsorption, although the adsorption process was exothermic and the free energy of adsorption was negative, indicating weak physical adsorption. The Fourier transform infrared results showed blue shifts of the bands corresponding to δ(C-OH) at 1410 and 1043 cm -1 , indicating hydrogen bonding for the uptake of AT on talc surfaces or edges.

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