REGULARITIES OF EXTRACTION OF IONIC AND NONIONIC SURFACTANTS FROM THEIR BINARY AQUEOUS SOLUTIONS

Abstract

Dodecylpyridinium chloride and nonionic surfactants – Twins (Tween-20, Tween-40, Tween-80) from their binary equimolar aqueous solutions under conditions of varying the acidity of the medium from 2 to 12 have been experimentally studied. Possible mechanisms for the interaction of surfactants of various types in a wide range of pH values of the medium are proposed. Studies have shown that Twins are not sensitive to a change in the acidity of the medium, their extraction from binary solutions with sodium dodecyl sulfate and Dodecylpyridinium chloride increases over the entire pH range of the medium and reaches 92-98%. Dodecylpyridinium chloride is best extracted from binary aqueous solutions with Twins in strong acid (pH 2) and strong alkaline (pH 12) media. In a wide range of pH values of the medium, the degree of flotation extraction of sodium dodecyl sulfate from binary solutions is increased by about 15% as compared to its extraction from an individual solution. The maximum of flotation extraction of sodium dodecyl sulfate from both individual and equimolar binary aqueous solutions with Twins is observed in acidic (pH 7) and alkaline (pH 7-10) media. The coefficient of flotation separation for binary solutions of Tween-sodium dodecyl sulfate is calculated, it which shows exactly how the surfactant is enriched with a foam fraction at a certain pH value. The formal study of the kinetics of flotation extraction of surfactants allowed to calculate the rate constant of the process and to establish the optimal flotation time. The time required for the maximum extraction of Twins and sodium dodecyl sulfate from the binary solution has reduced in comparison with individual solutions and it is about 2-3 minutes, and for extraction of Twins and Dodecylpyridinium chloride from their binary solution it is 5-7 minutes. The values of the rate constants of flotation are increased by 2-5 times for Twins, 3,5-5 times for sodium dodecyl sulfate when they are extracted from binary solutions of Tween- sodium dodecyl sulfate as compared to extraction from individual solutions; ≈ 1,5 – 3 times for Twins and 1,5 – 3 times for Dodecylpyridinium chloride when they are extracted from binary solutions of Twin – Dodecylpyridinium chloride. The obtained results can be used in the selection of optimal technological parameters for flotation of ionic and non-ionic surfactants.

Keywords

• флотація, поверхнево-активна речовина, Твіни, хлорид додецилпіридинію, додецилсульфат натрію