INFLUENCE OF POLYVINIL ALCOHOL ON THE SURFACE PROPERTIES OF IONOGENIC SURFACTANT – TWEEN MIXTURES

Abstract

A colloid-chemical approach was used to describe the process of surface concentration of Tweens (Tw-60, Tw-80), sodium dodecylsulfate (SDDS), chloride dodecylammonium (HDDA) from multicomponent aqueous solutions. The possibility of increasing the degree of flotation isolation of SDDS and HDDA when they are together in a solution with Tweens in the presence of polyvinyl alcohol (PVA) has been confirmed. During the flotation treatment of binary solutions of ionic (HDDA, SDDS) and nonionic (Tw-60, Tw-80) surfactants of different composition, the degree of flotation isolation increases be 10–25% on average when compared with their isolation from individual solutions. The addition of PVA, which is used as high molecular weight reagent, in the form of a 0.15–1.0% aqueous solution in the amount of 0.5–2.0 cm3 per 25–50 cm3 of a mixed surfactants solution lead to increase the degree of isolation of Tweens and SDDS. According to Rosen’s model, the composition of mixed adsorption layers at the boundary between the solution and air phases was calculated, as well as the parameters of intermolecular interaction in adsorption layers. For all mixtures of surfactants at any ratio of components, adsorption layers are formed, most of which are enriched with more surface-active Tw-60 and Tw-80. With the composition of the mixture of SDDS-Tw-60 n(SDDS): n(Tw-60)=0.7:0.3, almost equimolar adsorption layers are formed. At different mole rations of surfactants in mixed systems in solution, the molar fraction of Tw-60 in the adsorption layers of the HDDA-Tw-60 mixtures is greater than that of the SDDS-Tw-60 mixtures. The value βσ depends on the type and composition of the mixture, the nature of the surfactant. This effect is most pronounced at a high content n(Tween) = 0.7 in the solution (here the maximum values (by absolute value) of the intermolecular interaction parameter are observed. The expediency of using the parameter of surfactants in mixed adsorption layers to predict their surface concentration during isolation from multicomponent aqueous solutions and wastewater is shown.