烷基芳基磺酸盐结构对微乳液热力学性质的影响

用稀释法研究了自制的6种不同结构的烷基芳基磺酸盐(AAS)在多组分体系中形成微乳液的标准热力学函数，并考察了分子结构、温度、短链醇、含水量和无机盐含量对其的影响。 结果表明，随着烷基芳基磺酸盐分子长烷基链碳原子数的增加，导致表面活性剂/正丁醇/正癸烷/水形成的微乳液体系中醇由油相转移到界面相的标准自由能ΔG0o→i减小，有利于微乳液的形成；ΔH0o→i无明显变化，ΔS0o→i增大，且与烷基链碳原子数呈线性关系。 ΔS0o→i=1.7975n+71.538。 随着表面活性剂分子芳环向烷基链中间位置移动，导致表面活性剂/正丁醇/正癸烷/水形成的微乳液体系中醇由油相转移到界面相的标准自由能ΔG0o→i减小，有利于微乳液的形成；ΔS0o→i增大，ΔH0o→i减小；温度的升高导致微乳液体系的ΔG0o→i减小，微乳液的形成更容易。随醇碳链上碳原子数增加，ΔG0o→i减小，有利于微乳液的形成，且ΔG0o→i与碳原子数n呈线性关系，ΔG0o→i=-2790.8n+7286.4(328 K)；含水量的增加导致ΔG0o→i增大，不利于微乳液的形成，且ΔG0o→i与含水量V也呈线性关系。 ΔG0o→i=6697.8V-7170.4(318 K)；无机盐浓度的增加导致ΔG0o→i减小，有利于微乳液的形成。

Thermodynamic Properties of Microemulsion Formed by Different Kinds of Alkyl Aryl Sulfonates

The thermodynamic properties of microemulsion formed by six kinds of alkyl aryl sulfonates(AAS, synthesized in the laboratory) in the multi-component systems were investigated by dilution method. The influences of molecular structure, temperature, short chain alcohol, water content and salt concentration were respectively discussed. The results show that the increase of long alkyl carbon atom number(in alkyl aryl sulfonate molecule) causes the ΔG0o→i of the AAS/n-butanol/n-decane/water microemulsion systems decrease, along with the increase of the ΔS0o→i, and facilitates the formation of the microemulsion. The ΔS0o→i and carbon atom number of alkyl chain are in linear relationship, with ΔS0o→i=1.7975n+71.538. The ΔH0o→i is a constant. As the aromatic rings shift from the edge to the middle of the long carbonic chains, the ΔG0o→i of the microemulsion systems decreases, along with the decrease of ΔS0o→i and ΔH0o→i, facilitating the formation of the microemulsion. With the increase of temperature, ΔG0o→i of the microemulsion systems increase, hindering the formation of the microemulsion. The increase of carbon atom number of the alcohol causes ΔG0o→i decrease, which enables the formation of the microemulsion. ΔG0o→i and carbon atom number of the alcohol are in linear relationship, with ΔG0o→i=-2790.8n+7286.4(328 K). The increase of water content causes ΔG0o→i increase and the formation ability of the microemulsion decreases. ΔG0o→i and the volume of water are in linear relationship, with ΔG0o→i=6697.8V-7170.4(318 K). The increase of salt concentration causes ΔG0o→i decrease, and the formation ability of the microemulsion increases.