皂荚素的表面活性及其二元体系的热力学研究

通过表面张力的测定研究了皂荚素(GS)的表面活性及其热力学性质随温度的变化.测定了皂荚素分别与十二烷基磺酸钠、十二烷基聚氧乙烯醚硫酸钠、全氟辛酸钠、十二烷基脂肪醇聚氧乙烯(9)醚、辛基酚聚氧乙烯(10)醚及十六烷基三甲基溴化铵等复配的表面张力-浓度对数关系(γ～lgc)曲线,并用二维晶格模型及正规溶液理论计算了含皂荚素的二元表面活性剂溶液表面吸附层的组成、分子相互作用参数及分子交换能.结果表明,皂荚素主要呈现非离子表面活性剂的性质,与阳离子表面活性剂复配呈微弱的离子性.复配后分子交换能均小于零,复配增效.增效顺序为GS/阳离子>GS/非离子>GS/阴离子(表面活性剂复配体系).

Studies of the Surface Activity of Gleditsin and the Thermodynamic Properties of Its Binary Mixtures

The surface activity and the thermodynamic properties of gleditsin saponin(GS)(C₂₉ H₄₆(OH)COOH) were studied by surface tension method at 0, 15, 25, 35, 45 and 60 ℃. With the method, the surface activity of its binary aqueous solutions with C₁₂ H₂₅-SO₃Na(AS), C₁₂ H₂₅ (OC₂H₄)₃-SO₄Na(AES), C₇F₁₅ CO₂Na(OBS), C₁₆ H₃₃ NMe₃ Br(CTAB), C₈H₁₇-Ph(EO)₁₀ OH(Triton) and C₁₂ H₂₅ (EO)₉OH(AEO₉) were also studied at 25 ℃. The composition of the surface adsorption layers, molecular interaction parameters and the molecule exchanging energy of surfactants of these mixtures were calculated according to the dimensional crystal model and the regular solution theory with the help of the curves γ～lg c. The relationship between activity and molecule exchanging energy of surfactants were emphatically discussed. The results show that gleditsin saponin mainly acts as a nonionic surfactant in aqueous solution but as a weak acid anionic surfactant when mixed with cationic CTAB. The synergism order of its binary mixtures is: GScationic>GSnonionic>GSanionic.