An alternative to the conventional dilution method using temperature changes to stabilize/destabilize reverse micelles containing cosurfactant.

An alternative to the conventional dilution method (CDM) to characterize reverse micelles (RMs) containing cosurfactant is presented. This method can be performed following two routes: (i) adding oil to destabilize a RM and applying temperature changes to stabilize it again and (ii) applying temperature changes to destabilize the RMs and adding cosurfactant to stabilize it again. The destabilization-stabilization cycles in the proposed method can be related to the destabilization-stabilization cycles in CDM. Thus, by using the same theoretical fundaments, it is possible to obtain the same parameters that are obtained in CDM. RMs formed by the CTABþpentanol/hexane/water system was used to compare both methods. The amount of pentanol at the water/oil interface and in the oleic phase, as well as the thermodynamic parameters of the transfer process of pentanol molecules from the oleic phase to the oil/water interface obtained by both methods were similar. Using temperature changes as stabilizing/destabilizing agents presents some advantages: (i) By replacing oil and cosurfactant by temperature changes, the amount of reactants used in the experiments decreases, which also reduces the final waste; (ii) it is possible to obtain data at any temperature, as long as it falls within the temperature range used (this range is within the temperature range where the RMs are stable), which reduces the number of experiments; (iii) the direction of the temperature changes indicates whether the RMs formation process is endothermic or exothermic. The proposed method is an alternative to characterize RMs containing cosurfactants. [ABSTRACT FROM AUTHOR]