The Effects of Surface Lactone Hydrolysis and Temperature on the Specific and Nonspecific Interactions Between Phenobarbital and Activated Carbon Surfaces

The effect of hydrolyzing lactone functional groups on the surfaces of different activated carbons upon the specific and nonspecific interactions between phenobarbital and activated carbon surfaces was studied. The effect of temperature on both specific and nonspecific interactions was also studied. The increase in OH groups on the surfaces of activated carbons, as a result of hydrolyzing surface lactone groups, caused an increase in the specific adsorption capacity (K2) for phenobarbital without having a significant effect on the hydrophobic bonding capacity (KHB). Increasing the temperature at which the adsorption experiment was carried out, on the other hand, resulted in a decrease in KHB without having a significant effect on K2. The decrease in KHB per unit temperature increase was the same regardless of the activated carbon. These results are in very good agreement with the modified-Langmuir-like equation (M-LLE). © 2006 Wiley-Liss, Inc. and the American Pharmacists Association.