关键词: 聚电解质, 阴离子表面活性剂, 烷基苯磺酸盐, 多价阳离子, 热力学模型, 沉淀, 游离钙离子浓度, 临界胶束浓度, 硅酸钠, 磷酸盐

Abstract: The effects of polyelectrolytes such as silicates and phosphates on the dissolution/precipitation/redissolution of aJkylbenzene sulfonate in a multiva-lent cation aqueous solution have been studied in this paper.It turns out that,the addition of polyelectrolytes gives an increase in the sulfonate tolerance for the multivalent cation to a different degrees depending upon the concentration and the chelation of polyelectrolytes.Within the limits of chelation,as the polyelectrolytes concentration is increased,the sulfonate tole-rance of the maltivalent cation increases.The sulfonate tolerance of the cation in presence of higher polymerization degree silicate is more than that in the presence of silicate with lower degree of polymerization.A thermodynamic model is presented for the precipitation and redissolution of olkylbenzene sulfonate in multivalent cation aqueous solution based on the solubility product of the sulfonate precipitates and the theory of double electric layer.The presented model takes the effect of polyelectrolytes on the electrical double layer,the formation of "mixed micelles" in the sulfonate-cations system,the variation of micelle surface potential and the chelation of polyelectrolytes to cations and the introduction of the degree of association of the multivalent cation with the micelles into consideration.Reasonable agreement in precipitation boundaries between the results of calculations with this model and those from actual experiment for alkylbenzene sulfonate-calcium.chloride system is obtained with or without polyelectrolytes.