Development of novel methodologies to analyze the adsorption kinetics of nonionic surfactants

When an aqueous surfactant solution is exposed to a clean water/air surface, it takes a finite time for the surfactant molecules to physically transport from the bulk aqueous solution to the surface in order to adsorb and reduce the surface tension. The time scales associated with the reduction in surface tension can vary between milliseconds to hours depending on the surfactant type and its concentration. Accordingly, development of a fundamental understanding of the underlying physical phenomena involved in the kinetics of surfactant adsorption will help to: (i) understand the observed Dynamic Surface Tension (DST) behavior of surfactants, and (ii) design optimal surfactant formulations for applications in which the surfactant adsorption kinetics plays a significant role in determining the effectiveness of the formulation. This thesis deals with modeling the adsorption kinetics of nonionic surfactants at prernicellar surfactant concentrations. Traditionally, the adsorption kinetics of nonionic surfactants at premicellar surfactant concentrations has been understood in the context of two models: (1) the diffusion-controlled model, which assumes that diffusion of surfactant molecules from the bulk solution to the surface is the rate-limiting step, and (2) the mixed diffusion-barrier controlled model, which hypothesizes the existence of an energy barrier for surfactant adsorption from the bulk solution to the surface, and assumes that both diffusion and the energy barrier determine the overall rate of surfactant adsorption. Although the existence of the energy barrier was hypothesized more than 50 years ago, the physical basis underlying the existence of the energy barrier has not yet been elucidated.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Chemical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2007

Author dc:creator

• Moorkanikkara, Srinivas Nageswaran

Advisor dc:contributor.advisor

• Daniel Balankschtein.

• 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/1721.1/42166

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/42166