Cooperative Adsorption of Dodecyltri(oxyethylene) Sulfate Ion and Calcium Ion on Inorganic Solid Particles in Electrolytes Solutions

Abstract

Relations between concentration of calcium ions and the amount of ions adsorbed (Γ _t) on iron(III) oxide (Fe₂O₃) or on titanium oxide (TiO₂) in solutions containing sodium dodecyltri (oxyethylene) sulfate (R₁₂O(E0)₃SO₃Na), sodium hydroxide, sodium chloride and calcium chloride were studied, in order to know the behavior of alkylpoly (oxyethylene) sulfate ions in hard water. These experiments were conducted under the following conditions; in the presence of definite concentration of R₁₂O(E0)₃SO₃Na and 0.3 mmol/l sodium hydroxide, at an ionic strength of 0.01 and at 25° C. Two kinds of linear increases of Γ _{R12O(EO)3SO3-} and Γ _ca2+ with increase in ratio of calcium ion concentration to the total concentration of cations (C_ca2+/(C_ca2++ C_Na+)) were found for Fe₂O₃ and TiO₂. The values of Γ _Na+ and on the other hand, were much smaller over the whole concentration ratio of C_ca2+/(C_ca2++ C_Na+) (Figs.1, 2 and 3). These results show that the cooperative adsorption of R₁₂O(E0)₃SO₃^- and calcium ions on Fe₂O₃ and TiO₂ takes place in the presence of other ions. Stern charge densities (σ) around Fe₂O₃ or TiO₂ particles were calculated from the obserbed values of Γ_t.Maximumvalues of σwerefoundonthecurvesofσvs.C_ca2+/(C_ca2++ C_Na+)duetothemutualchargecancellationofR₁₂O(E0)₃SO₃^-andcalciumionsonFe₂O₃or TiO₂(Fig.5).