Theoretical and experimental investigation of the equilibrium and dynamic interfacial behavior of mixed surfactant solutions

In many commercial applications involving surfactants, the desired properties are controlled by both the equilibrium and the dynamic interfacial behavior. In particular, surfactant adsorption at air-water interfaces causes the surface tension to decrease, which, for example, can control the spreading properties of a liquid, and hence, is important in practical applications involving the use of paints and pesticides, as well as in the manufacturing of photographic films. Similarly, surfactant adsorption at oil-water interfaces causes the interfacial tension to decrease, which, for example, can enhance the ability of surfactant solutions to remove oily soil from dirty surfaces (fabric, hair, skin, etc.) during cleaning applications. A predictive, molecular-thermodynamic theory capable of modeling the behavior of surfactants at solution interfaces would help minimize the need for costly and time-consuming experimentation associated with the development of surfactant products based on a trial-and-error approach. Furthermore, this theory should encompass mixtures of surfactants, since their use in industrial applications is widespread, whether intentionally, to take advantage of synergism between the surfactant components in a mixture, or simply because it is too costly to mass produce a single, pure surfactant. With this as motivation, a molecularly-based theoretical framework to model both the equilibrium and the dynamic adsorption of surfactant mixtures at both the air-water interface and the oil-water interface has been developed. The equilibrium air-water surface equation of state is based on a two-dimensional, nonideal gas-like monolayer model of the adsorbed surfactant molecules. For non-ionic surfactants, two types of interactions were accounted for:

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Chemical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2001

Author dc:creator

• Mulqueen, Michael (Michael Patrick), 1972-

Advisor dc:contributor.advisor

• Daniel Blankschtein.

• Chemical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/82758

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/82758