Abstract

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 CTAB + pentanol/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.

摘要

提出了一种替代传统稀释法 (CDM) 来表征含有辅助表面活性剂的反胶束 (RM) 的方法。该方法可以通过以下两种途径执行：(i) 添加油以破坏 RM 的稳定性并应用温度变化以再次稳定它，以及 (ii) 应用温度变化以破坏 RM 的稳定性并添加助表面活性剂以再次稳定它。所提出方法中的失稳-稳定循环可能与 CDM 中的失稳-稳定循环有关。因此，通过使用相同的理论基础，可以获得与 CDM 中相同的参数。由 CTAB + 戊醇/己烷/水系统形成的 RM 用于比较这两种方法。水/油界面和油酸相中戊醇的量，以及两种方法得到的戊醇分子从油酸相向油/水界面转移过程的热力学参数相似。使用温度变化作为稳定剂/去稳定剂有一些优点：（i）通过温度变化代替油和辅助表面活性剂，实验中使用的反应物量减少，这也减少了最终废物；(ii) 可以在任何温度下获得数据，只要它落在使用的温度范围内（这个范围在RM稳定的温度范围内），从而减少了实验次数；(iii) 温度变化的方向表明 RMs 形成过程是吸热还是放热。所提出的方法是表征含有助表面活性剂的 RM 的替代方法。