Counterion effect on the solution and thermodynamic properties of lithium perfluoroalkanoates
Counterion effect on the solution and thermodynamic properties of lithium perfluoroalkanoates
复制标题
反离子对全氟链烷酸锂溶液和热力学性质的影响
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
F. Sarmiento
中科院分区：
文献类型：
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作者：
E. Blanco;P. Messina;J. Ruso;G. Prieto;F. Sarmiento
测定了全氟辛酸锂和全氟十一酸锂的电导率等温线，并在高于Krafft点的温度范围内测定了临界胶束浓度cmc和胶束电离度β。从提出的热力学模型确定了胶束形成的热力学参数吉布斯自由能、焓和熵。两种表面活性剂的表观摩尔体积和表观摩尔绝热压缩系数已计算出在很宽的浓度范围内从密度和超声波速度测量。在稀溶液中，表观摩尔体积与Debye-Hückel极限定律的正偏差表明存在预胶束聚集。全氟十一酸锂的绝热压缩系数斜率从正到负的变化被解释为溶质-溶剂相互作用。动态表面张力测量使我们能够计算扩散系数，面积和聚集数。这些值进行了讨论，比较相应的钠化合物。
The isotherms of conductivity of lithium perfluorooctanoate and perfluoroundecanoate were measured and the critical micelle concentration, cmc, degree of ionization of the micelles, β, determined in a range of temperatures above the Krafft point. The thermodynamic parameters, Gibbs free energy, , enthalpy , and entropy of micelle formation, were determined from a proposed thermodynamic model. Apparent molar volume and the apparent molar adiabatic compressibility for both surfactants have been calculated over a wide concentration range from density and ultrasound velocity measurements. Positive deviations of the apparent molar volume from the Debye–Hückel limiting law in dilute solutions indicate the existence of premicellar aggregation. Changes in the slope of adiabatic compressibility of lihium perfluoroundecanoate from positive to negative have been interpreted in terms of solute solvent interactions. Dynamic surface tension measurements allow us to calculated diffusion coefficients, areas and aggregation numbers. These values are discussed comparing the corresponding sodium compounds.