物理化学学报Issue(2)：351-357,7.DOI:10.3866/PKU.WHXB201211214
十二烷基硫酸钠水溶液的动态表面吸附性质
Dynamic Surface Adsorption Properties of Sodium Dodecyl Sulfate Aqueous Solution
摘要
Abstract
The dynamic surface adsorption properties of aqueous sodium dodecyl sulfate (SDS) solutions were investigated at different concentrations of NaCl using bubble pressure tensiometry MPTC. In the case of ionic surfactants, the existence of a diffuse electric double layer on the surface adsorption layer and around the micel e produces a surface charge. Here, we discuss the influence of the surface charge on the dynamic surface diffusion processes and the micel e properties. It was found that the SDS adsorption process occurred in the presence of a 5.5 kJ·mol-1 adsorption barrier (Ea) that was generated by the surface charge; this barrier significantly decreased the effective diffusion coefficient (Def ) of the dodecyl sulfate ions (DS-). The ratio of the effective diffusion coefficient to the monomer self-diffusion coefficient (D) (Def/D) was only 0.013. This indicated that at the beginning, the adsorption of SDS fol owed the mixed kinetic-diffusion control ed model; this is different from the behavior observed for nonionic surfactants. The adsorption barrier was reduced when NaCl was added. Ea was less than 0.3 kJ·mol-1 after the addition of 80 mmol·L-1 of NaCl. This resulted in values of between 0.8 and 1.2 for Def/D, which was consistent with the diffusion-control ed model that describes the behavior of nonionic surfactants. The characteristic constants for the micel e dissociation rate (k2) were determined from the dynamic surface tension of the SDS micel e solutions. The calculated k values decreased as the NaCl concentration was increased, which demonstrated the existence of surface charge on the SDS micel es; this surface charge increased the repulsive forces between the dodecyl sulfate ions, and promoted the dispersion of the micel es.关键词
十二烷基硫酸钠/动态表面张力/表面电荷/吸附势垒/胶束解体Key words
Sodium dodecyl sulfate/Dynamic surface tension/Surface charge/Adsorption barrier/Micel e dissociation分类
化学化工引用本文复制引用
范海明,张一诺,张进,王东英,高建波,康万利,孟祥灿,赵健,徐海..十二烷基硫酸钠水溶液的动态表面吸附性质[J].物理化学学报,2013,(2):351-357,7.基金项目
The project was supported by the Taishan Scholars Construction Engineering of Shandong Province (ts20070704), National Natural Science Foundation of China (51234007,51104169), Natural Science Foundation of Shandong Province, China (ZR2010BQ003, ZR2010EZ006), and National Undergraduate Innovative and Entrepreneurship Training Program of China University of Petroleum (East China), China (201210425011).@@@@山东省“泰山学者”建设工程(ts20070704),国家自然科学基金(51234007,51104169),山东省自然科学基金(ZR2010EZ006, ZR2010BQ003)与中国石油大学(华东)国家大学生创新创业训练计划(201210425011)资助项目 （ts20070704）
