Molecular interaction and synergism in binary mixtures of surfactants at the solid/liquid interface.
Item
-
Title
-
Molecular interaction and synergism in binary mixtures of surfactants at the solid/liquid interface.
-
Identifier
-
AAI8914754
-
identifier
-
8914754
-
Creator
-
Gu, Ben.
-
Contributor
-
Adviser: Milton J. Rosen
-
Date
-
1988
-
Language
-
English
-
Publisher
-
City University of New York.
-
Subject
-
Chemistry, Physical
-
Abstract
-
A nonideal solution treatment has been developed and used to calculate the mole fractions, X, and interaction parameters, {dollar}\beta{dollar}, between two surfactants in the monolayer at various interfaces. Treatment "R", based upon the assumption of the same ratio of interfacial areas in the mixed and individual surfactant monolayers, gives X values in close agreement with these obtained by using the Gibbs equation and a {dollar}\beta{dollar} value that is essentially constant with change in X and surface pressure, {dollar}\pi{dollar}. Treatment "E", based upon the assumption of insignificant change in surfactant molar area in the mixture, gives X and {dollar}\beta{dollar} values that deviate more.;Equations have been derived for the conditions under which synergism in interfacial tension reduction efficiency in binary mixtures of surfactants at the liquid/hydrophobic solid interface and for various properties of the mixture at the point of maximum synergism. The dependence of attractive interaction between two surfactants in the monolayer on the nature of the solid surface, the ionic strength of solution, the chain length and the structure of the surfactants has been studied.;New equations, based upon the Butler equation and combining the 2-D gas and 2-D solution approaches, are used to calculate the adsorption free energies of mixed surfactants at the L/V and S/L interfaces. Both standard free energies of adsorption, calculated from Rosen-Aronson equation, and those obtained by the new equations become more negative with increasing surfactant chain length at all interfaces investigated and a linear relationship was found at the L/V interface. But the increment decreases with increase in chain length at the S/L interfaces.;The relative adsorption of the surfactants at the solid/liquid and liquid/vapor interfaces, determined by using adhesion tension vs. surface tension plots, decreases in the order: Parafilm {dollar}>{dollar} Teflon {dollar}>{dollar} polyethylene and this is consistent with the results obtained by using Gibbs adsorption equation. The critical surface tensions of Teflon and Parafilm obtained by extrapolating the plots of {dollar}\gamma\sb{lcub}\rm lv{rcub}{dollar}Cos{dollar}\theta{dollar} vs. {dollar}\gamma\sb{lcub}\rm lv{rcub}{dollar} from cationic-anionic surfactant mixtures and pure liquids are identical.
-
Type
-
dissertation
-
Source
-
PQT Legacy CUNY.xlsx
-
degree
-
Ph.D.
