表面活性剂在低能固体表面上的吸附——Ⅰ.γ-θ法研究辛基硫酸钠、溴化辛基三甲胺及其等比混合物在石蜡/水溶液界面上的吸附

INVESTIGATION OF SURFACTANTS ADSORPTION ON LOW-ENERGY SOLID SURFACE

(1) 用γ-θ法研究C_8H_(17)SO_44Na、C_8H_(17)N(CH_3)_3Br及其1:1混合物在石蜡/水溶液界面上的吸附,得到Langmuir型吸附等温线。 (2) 首次计算两表面活性剂在固/液界面吸附层中的分子相互作用参数,并与它们在气/液、液/液界面吸附层中的数值相比较。 (3) 结果表明γ-θ法不仅简单、方便、样品用量少,而且有获得信息多的特点,用几毫升样品可得到有关体系表面性质的十多种数据。

Surface tension[gamma] of aqueous solutions of C8H17SO4Na, C8H17N(CH3)(3)Br and the 1:1 mixture of them have been measured by drop volume method, and their contact angles [theta] on paraffin wax by a microseopefitted with a goniometer. According to Young equation, the L/S interface pressures were obtained from gamma and theta data. Gibbs adsorption equation was applied for L/S interface to work out the adsorstion isotherms It is seen that the adsorption isotherms are of Langmuir type. It would be the first time to calculate the molecular interacion parameter of mixed surfactants adsorption layer at L/S interface and to give beta(sigma) values of the same pair of surfactants in A/L, L/L, L/S interface layers. It has been pointed out that this method is simple, convenient and only a few ml solution is needed for obtaining more than ten different surface properties: surface tension of solution, adsorption at A/L interface, composition of the adsorbed layer at A/L interface, critical micelle eoncentration, contact angle, critical surface tension of solid, L/S interface pressure, adsorption at L/S interface, composition of the adsorbed layer at L/S interface, molecular interaction parameter in A/L and L/S interface adsorbed layer and in micelle, etc.