Co-Solubilization of the Binary Mixture of 1-Naphthol and 2-Naphthol in the Water Micellar Solution of Sodium Cholate and Cetyltrimethylammonium Bromide

Abstract

The micellar co-solubilization of α- and β-naphthol and their binary mixture with surfactants sodium cholate (SC) and cetyltrimethylammonium bromide (CTAB) is examined. The micellar solubilization of 2-naphthol (2-NpOH) in SC is entropic, and it is an energetically more favored process than the micellar solubilization of 1-naphthol (1-NpOH). The capacity of the solubilization by CTAB for solubilizing 1- and 2-naphthol is about eight-times higher at 4CMC than at 2CMC (four- and two-times the critical micelle concentration, respectively), which can be explained by the change in the micelle structure with an increase in the total concentration of the CTAB surfactant. For the same CMC values of the examined surfactants, SC has a higher solubilization capacity for naphthols in comparison to the solubilization capacity of CTAB, which is explained by the existence of hydrogen bonds between the building units and solubilizates that are formed in the SC micelles. For each molar ratio of the micellar binary mixture...