Adsorption Properties and Composition of Binary Kolliphor Mixtures at the Water–Air Interface at Different Temperatures

Abstract

The studies on the adsorption properties and composition of the adsorbed monolayer at the water–air interface of the binary Kolliphor® ELP (ELP) and Kolliphor® RH 40 (RH40) mixtures based on the measurements of the surface tension (γLV) of their aqueous solution in the temperature range from 293 to 318 K were carried out. The γLV isotherms were described by the exponential function of the second order and the Szyszkowski equation as well as predicted by Fainerman and Miller equation. The obtained γLV isotherms were analyzed using the exponential function of the second order, the Szyszkowski, Fainerman and Miller as well as independent adsorption equations. The γLV isotherms were also used for determination of the Gibbs surface excess concentration of RH40, ELP and their mixture (Γ) at the water–air interface as well as the mixed monolayer composition. Based on Γ and the constant a in the Szyszkowski equation, the standard thermodynamic functions of adsorption were considered. From the consideration dealing with the γLV isotherms obtained by us, it results, among others, that these isotherms for the non-ideal solution of macromolecular surfactants mixture can be predicted using the Fainerman and Miller equation. From this consideration, it also results that a simple method proposed by us, based on the isotherms of RH40 and ELP, allows us to predict the composition of their mixed monolayer in the whole concentration range of RH40 and ELP in the bulk phase.

Thermodynamic Analysis of the Adsorption and Micellization Activity of the Mixtures of Rhamnolipid and Surfactin with Triton X-165

“…It seems, however, that despite the strong interactions between the TX165 molecules and those of biosurfactants, the mole fraction of the mixture components in the mixed monolayer at the water–air interface does not differ much from that calculated based on the monolayer pressure of individual compounds. This conclusion confirms the surface tension isotherms of the aqueous solution of TX165 mixtures with the biosurfactants determined from the following expression [ 33 ]: …”

“…It seems reasonable to assume that the of the TX165 mixtures with RL or SF is equal to where is the mole fraction of the particular surfactants in the mixture and 1, 2, and 12 refer to TX165, the biosurfactant, and the mixture of TX165 with the biosurfactant, respectively. As was stated earlier [ 33 ], and ( and are the layers surfactants 1 and 2 pressure, respectively). Taking into account the values determined in this way, the values for the TX165 + RL and TX165 + SF mixtures at a given concentration and composition were deduced.…”

“…The isotherms of the of the aqueous solution of many surfactants are often described by the Szyszkowski equation [ 27 ]. However, in the case of the aqueous solution of surfactant mixtures, fewer attempts to describe the of these solutions by the Szyszkowski equation are reported in the literature [ 33 ]. It is commonly known that in the Szyszkowski equation depends on the maximal Gibbs surface excess concentration ( ), the concentration of surfactants in the bulk phase ( ), and the standard Gibbs free energy of adsorption ( ), which is represented by the constant in this equation.…”

Behavior of Auramine O in the Aqueous Solution of Two Kolliphors and Their Mixture

“…The determination of the surface tension components and parameters of ELP and RH40 is not easy. It was found that the minimal surface tension of the aqueous solution of surfactants satisfies the condition [ 10 ]: where X S and X W are the fraction of the interface area occupied by the surfactant and water, and γ S and γ W are the surface tension of the surfactant tail and water.…”

“…The large hydrophobic tail of the ELP and RH40 molecules includes three hydrocarbon chains with one –OH group in each chain. The hydrophilic head of these surfactants includes oxyethylene groups [ 10 , 11 ]. Due to the large contact area of the hydrophobic parts of ELP and RH40 molecules, it is possible that strong interactions can occur between these parts and the AuO molecules, resulting in the great effect of AuO on the adsorption and aggregation of ELP and RH40 as well as their mixtures.…”