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Swobodna energia międzyfazowa a swobodna energia adsorpcji i micelizacji substancji powierzchniowo czynnych

Jańczuk B., Wójcik W., Zdziennicka A., Gonzalez-Martin M.A., Bruque J.M.

Wiadomości Chemiczne

2000

[Z] 54, 9-10

793-815

This paper reviews the results of investigations of the surface free energy of surfactants and the correlation between hydrophobic group of surfactant-water and hydrophilic group of surfactant-water interfacial free energy and standard free energy of adsorption at water-air (oil) interface and standard free energy of micellization. The surface free energy of the hydrophobic and hydrophilic group of the surfactants is considered separately. The van Oss and co-workers' approach to the interfacial liquid-liquid and solid-liquid free energy used for the energy determination has been described. This approach treats the surface free energy of a solid and a liquid as the sum of the Lfshitz-van der Waals and Lewis acid-base components. The acid-base component of the surface free energy depends on the electron-acceptor and electron-donor parameters of this energy. Different determination ways of the surface free energy components and parameters of the hydrophobic and hydrophilic group of the surfactants are shown. The usefulness of the Young equation and adsorption data of n-alkanes on solid surface for determination of the Lifshitz-van der Waals component and electron-acceptor parameters of the acid-base component of the hydrophilic group of the surfactants is presented. On the basis of the surface free energy components and parameters of the hydrophobic and hydrophilic group of the surfactants and recently modified DLVO theory, the free energy of interaction between molecules or ions of the surfactants through the water phase and the free energy of removing surfactant molecules or ions from the water phase to air or oil phase can be predicted. The modified DLVO theory treats the interaction between molecules or particles through the liquid phase as the sum of Lifshitz-van der Waals, acid-base and electrostatic interaction components, which details are described for the systems including ionic or nonionic surfactants. The free energy of interaction can be used for prediction of the standard free energy of adsorption and micellization of the surfactants if the contactable area of the molecules or ions of the surfactants is known. Different ways of the contactable area between the hydrophobic and hydrophilic group of the surfactants and between groups and water molecules are presented. The calculated values of the free energy of interactions of the surfactants through water phase are compared to the standard free energy of micellization and the standard free energy of the adsorption of surfactants at water-air (oil) interface. For this purpose the determination of the standard free energy of adsorption from isotherms of adsorption of the surfactants and their standard free energy of micellization is also described.