Solubilization of benzene and its homologues with aqueous solutions of ethoxylated surfactant

Solubilization of benzene, toluene and pseudocumene with aqueous solutions of polyethylene glycol decylether with a degree of ethoxylation equal to 15 was studied. An attempt to elucidate the local environment of these compounds in micelles was made. It is found that, the more complex the molecular structure of the aromatic hydrocarbon, the less the amount of this compound, which can be solubilized with an aqueous solution of the surfactant under investigation, and the higher the temperature, at which the greatest amount of the compound is solubilized. The heat effects of dissolution of the aromatic hydrocarbons in micelles were determined from the temperature dependences of their solubilization. The values of Delta H were found to be within the range 15-26 kJ/mol, corresponding to the energy of the van der Vaals interactions. Using ultraviolet spectroscopy, it was shown that solubilized benzene has a polar microenvironment, i.e., is mainly concentrated in the outer layer of micelles, which consists of poly(oxyethylene) chains, whereas, toluene and pseudocumene are located mainly in the hydrocarbon core of micelles.