The kinetics of solubilization of single component non-polar oils by a non-ionic surfactant

Abstract

The kinetics of solubilization of two non-polar oils (hexadecane and 2,6,10,15,19,23 hexamethyl tetracosane) by a pure non-ionic surfactant (n-dodecyl hexaethylene glycol ether) have been investigated using a recently developed technique. A linear dependence of rate upon surfactant concentration above the cmc and a rapid increase in rate at temperatures close to the cloud point were observed. A previously developed theoretical description of the process has been expanded to account for the observation that the rates for the oils in given systems are not in the exact ratio of the equilibrium capacities of the system for the respective oils. If the effects of changes in aggregation number and shape of the micelle/solubilizate complex are considered, the absolute values of the measured and theoretical rates are in good agreement. Furthermore, the activation energies are nearly equal for the two solubilizates, a result which is in accord with theory. The micelle relaxation time τ2 is practically independent of surfactant concentration.