Adsorption Properties of Hydrocarbon and Fluorocarbon Surfactants Ternary Mixture at the Water-Air Interface.

Bronisław Jańczuk,Anna Zdziennicka,Katarzyna Szymczyk

doi:10.3390/molecules26144313

Bronisław Jańczuk, Anna Zdziennicka + Show 1 more

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https://doi.org/10.3390/molecules26144313

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Abstract

Measurements were made of the surface tension of the aqueous solutions of p-(1,1,3,3-tetramethylbutyl) phenoxypoly(ethylene glycols) having 10 oxyethylene groups in the molecule (Triton X-100, TX100) and cetyltrimethylammonium bromide (CTAB) with Zonyl FSN-100 (FC6EO14, FC1) as well as with Zonyl FSO-100 (FC5EO10, FC2) ternary mixtures. The obtained results were compared to those provided by the Fainerman and Miller equation and to the values of the solution surface tension calculated, based on the contribution of a particular surfactant in the mixture to the reduction of water surface tension. The changes of the aqueous solution ternary surfactants mixture surface tension at the constant concentration of TX100 and CTAB mixture at which the water surface tension was reduced to 60 and 50 mN/m as a function of fluorocarbon surfactant concentration, were considered with regard to the composition of the mixed monolayer at the water-air interface. Next, this composition was applied for the calculation of the concentration of the particular surfactants in the monolayer using the Frumkin equation. On the other hand, the Gibbs surface excess concentration was determined only for the fluorocarbon surfactants. The tendency of the particular surfactants to adsorb at the water-air interface was discussed, based on the Gibbs standard free energy of adsorption which was determined using different methods. This energy was also deduced, based on the surfactant tail surface tension and tail-water interface tension.

Highlights

IntroductionThe ability of surfactants to adsorb at various interfaces and to form micelles in the bulk phase determines their wetting, emulsifying, solubilizing, dispersing, and foaming properties [1]
In the case of surfactant molecules oriented by head towards the air phase, the surface tension refers to the head
As the surfactant molecules in the monolayer at the water-air interface are oriented by their tail towards the air phase, the values of the surface tension of the aqueous solution of the mixture including two hydrocarbon and one fluorocarbon surfactants depend on those of the water and surfactant tail surface tension

Summary

Introduction

The ability of surfactants to adsorb at various interfaces and to form micelles in the bulk phase determines their wetting, emulsifying, solubilizing, dispersing, and foaming properties [1]. These properties are the basis for the wide application of surfactants in various industrial fields: pharmacy, medicine, agriculture, and in everyday life [2,3,4,5]. Surfactant molecules undergo hydration in the aqueous environment. The hydration of the tail of a surfactant molecule increases the Gibbs free energy of surfactant aqueous solution and hydration of the head causes its decrease

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