阴离子混合表面活性剂体系的胶束性质

为了研究化学驱中表面活性剂复配体系的混合胶束性质,为表面活性剂复配体系的色谱分离预测提供必要的参数,测定了十二烷基苯磺酸钠(SDBS)和十二酸钠(SLA)以及SDBS和十四烷基苯磺酸钠(STBS)两种混合体系的表面张力,考察了电解质浓度、种类对混合体系临界胶束浓度和相互作用参数的影响。实验结果表明,在无机电解质浓度远大于表面活性剂浓度时,烷基链长不同的磺酸盐的混合胶束形成性质可用Clint模型描述,而磺酸盐和羧酸盐的混合表面活性剂临界胶束浓度(cmc)可用规则溶液理论(RST)来描述。对于SDBS／STBS混合体系,添加不同价态的阴离子对混合cmc的影响不同。在相同电解质浓度下,碱性和弱碱性条件使SDBS／SLA混合体系的cmc变化不大,但与中性相比下降很大;在碱性条件下,其值随组成的变化不大;在中性条件下,cmc的变化与碱性条件相比要大一些;在各种电解质浓度下,用规则溶液理论计算出的SDBS／SLA体系的相互作用参数皆为负值,表明混合胶束两表面活性剂分子之间的作用是相互吸引的。在相同表面张力下,混合表面活性剂的浓度比单一表面活性剂浓度低,因此,SDBS与SLA混合表面活性剂在降低表面张力效率方面能够产生明显的协同效应。图5表2参11

Micellar properties of mixed anionic-nonionic surfactants

For studying the property of the micelle of mixed surfactants in chemical flooding and applying data for the prediction of chromatography of the mixed surfactants, the surface tensions of sodium dodecyl benzene sulfonate (SDBS)/sodium laurate (SLA) and SDBS/sodium tetradecyl benzene sulfonate (STBS) were measured. The effect of the concentration and kind of inorganic electrolyte on the critical micelle concentration (cmc) and the relative reaction parameter of the mixed surfactants were investigated. The results show that Clint's Model could describe the mixed micelle formation property of the sulfonates with different alkyl chain length under higher concentration of inorganic electrolyte but that of the mixed surfactants of sulfonate and carboxylate could be described by the regular solution theory (RST). The influence of anionic ions with different chemical valence on the cmc of the system of SDBS/STBS was different. At the same concentration of electrolyte, the cmc of the SDBS/STBS solution in basic property was not changed but that in neutral property was decreased obviously. The solution in basic property cmc was not changed with the change of solution composition but that in neutral property was changed more obviously. The relative reaction parameters of (SDBS)/(SLA) solution containing different concentration of electrolyte calculated by RST were negative. At a same surface tension value, the concentration of the mixed surfactants of SDBS/SLA was lower than that of pure surfactant, suggesting synergism in surface tension reduction efficiency.