十六烷基二苯醚二磺酸钠表面化学性质及胶团化作用

用滴体积法通过表面张力的测定, 系统地研究了十六烷基二苯醚二磺酸钠(C₁₆-MADS)在不同温度(298.0～318.0 K)和不同NaCl浓度(0～0.50 mol•L^-1)下的表面活性. 结果表明, 温度升高使C₁₆-MADS溶液的临界胶束浓度(cmc)略有增大, 表面极限吸附量(Γ_∞)降低. cmc随NaCl浓度的增大从1.45×10^-4 mol•L^-1降至4.10×10^-5 mol•L^-1, 但最低表面张力(γ_cmc)基本不受影响. 在298.0 K与303.0 K时, NaCl浓度的增大, Γ_∞增大; 在308.0、313.0与318.0 K时, NaCl浓度的增大, 出现了Γ_∞从2.27 μmol•m^-2降低至1.41 μmol•m^-2的“反常”现象. 胶团形成自由能(ΔG_m⁰)随温度和NaCl浓度增加负值增大(－63.98～－76.20 kJ•mol^-1), 胶团的形成主要是熵驱动过程.

Surfactivity and Micellization of Disodium Hexadecyl Diphenyl Ether Disulfonate in Aqueous Solution

By using drop-volume method, the surface tension of disodium hexadecyl diphenyl ether disulfonate (C₁₆-MADS) was measured in different NaCl concentrations (0～0.50 mol•L^-1 NaCl) at different temperatures (298.0～318.0 K). The results show that with the increase of temperature, the critical micelle concentration (cmc) of C₁₆-MADS slightly increases, but the maximum surface excess concentration at the air/water interface (Γ_∞) decreases. The cmc of C₁₆-MADS decreases from 1.45×10^-4 mol•L^-1 down to 4.10×10^-5 mol•L^-1 as the concentration of NaCl increases from 0 to 0.50 mol•L^-1, but the corresponding surface tension at the concentration (γ_cmc) shows no variation. As the increase of NaCl concentration, Γ_∞ of C₁₆-MADS increases as the increase of temperature in the range of 298.0～303.0 K, but abnormally decreases from 2.27 μmol•m^-2 down to 1.41 μmol•m^-2 in the range of 308.0～318.0 K. The micellization free energies (ΔG_m⁰) are in the range －63.98～－76.20 kJ•mol^-1 in the studied ranges of temperature and NaCl concentration. The process of micellization of C₁₆-MADS in aqueous solution is mainly driven by the entropy.