A STUDY OF ORGANOGELS AND THEIR SOLUTE INTERACTIONS

Abstract

A brief background on bis(2-ethylhexyl) sodium sulfosuccinate (AOT) reversed micelles and organogels and survey of their general properties and some possible applications is presented. The AOT organogels are characterized in terms of their relative stability when contacted with different solvent systems (water, salt water, alcohols, alkanes). The gels were found to retain their structure in salt (NaCl) water and nonpolar solvents (hexane, heptanes). The density of the AOT organogel materials was found to be 1.05 g/ml. The partition coefficients for the interaction of solute molecules (substituted phenols, anilines, naphthols) with the organogels were found to be in the range of 1.3 to 500. These partition coefficients are roughly 40 times less relative to the partitioning of the same solutes to AOT reverse micelles in solution. The AOT organogels were found to function as a sorbent for the extraction of nitroanilines, phenols, and 2-naphthol from a bulk hexane solution. The extraction efficiencies ranged from 72 – 97% with enrichment factors from 3 – 13 depending upon the amount of AOT organogel employed. A pseudo-second order kinetic model was found to best fit the sorption the data for the solutes examined (2- and 4-nitroaniline, 2,4-dinitroaniline, and 2-naphthol). Finally, the Abraham solvation model was applied and binding to the AOT organogels was found to be dominated by hydrogen bond basicity and acidity with a secondary contribution from solute polarizability.