Electrolyte effect on mixed micelle and interfacial properties of binary mixtures of cationic and nonionic surfactants.
Electrolyte effect on mixed micelle and interfacial properties of binary mixtures of cationic and nonionic surfactants.
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DOI：
10.1016/j.jcis.2007.11.005
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发表时间：
2008-02
影响因子：
9.9
通讯作者：
S. Javadian;H. Gharibi;Zahra Bromand;B. Sohrabi
中科院分区：
文献类型：
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作者：
S. Javadian;H. Gharibi;Zahra Bromand;B. Sohrabi
采用表面张力法和电位法研究了十六烷基三甲基溴化铵（CTAB）和对-（1，1，3，3-四甲基丁基）聚氧乙烯醚（TritonX-100）在不同浓度NaBr水溶液中的液-气界面吸附行为和胶束化特性。从表面张力（γ）作为溶液组成和总表面活性剂浓度的函数的曲线图，我们确定了临界胶束浓度（CMC）、CMC下的最小表面张力（γCMC）、表面过量（Γmax）和平均分子表面积（Amin）。根据正规溶液理论，估算了吸附膜（Z）和胶束（XM）的组成，并计算了胶束中的相互作用参数（βM）和吸附膜相中的相互作用参数（βσ）。对于所有的摩尔分数比，结果表明协同增强的能力，形成混合胶束以及表面张力降低。此外，通过考虑非随机混合和头基大小效应来计算β。据观察，对于平面空气/水界面和胶束系统，非理想性降低的电解质在水介质中的量增加。这是由于溴离子浓度的增加引起的表面电荷密度的降低。
In the present work, the adsorption behavior at the liquid–air interface and micellization characteristics of mixtures of cetyltrimethylammonium bromide (CTAB) and p-(1,1,3,3-tetramethylbutyl) polyoxyethylene (TritonX-100) in aqueous media containing different concentrations of NaBr were investigated by surface tension and potentiometry measurements. From plots of surface tension (γ) as a function of solution composition and total surfactant concentration, we determined the critical micelle concentration (CMC), minimum surface tension at the CMC (γCMC), surface excess (Γmax), and mean molecular surface area (Amin). On the basis of regular solution theory, the compositions of the adsorbed film (Z) and micelles (XM) were estimated, and then the interaction parameters in the micelles (βM) and in the adsorbed film phase (βσ) were calculated. For all mole fraction ratios, the results showed synergistically enhanced ability to form mixed micelles as well as surface tension reduction. Furthermore β was calculated by considering nonrandom mixing and head group size effects. It was observed that, for both the planar air/aqueous interface and micellar systems, the nonideality decreased as the amount of electrolyte in the aqueous medium was increased. This was attributed to a decrease of the surface charge density caused by increasing the concentration of bromide ions.