Using "prosurfactants" to enhance rates of delivery of surfactants

• Published in: AIChE journal Vol. 50; no. 3; pp. 708 - 714
• Main Authors: Rosslee, Craig A., Khripin, Constantine, Foley, Theresa M. D., Abbott, Nicholas L.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.03.2004; Wiley Subscription Services; American Institute of Chemical Engineers
• Subjects: Chemical engineering; Chemistry; Exact sciences and technology; General and physical chemistry; hindered diffusion; Membranes; Oxidation; prosurfactant; redox; Surface physical chemistry; Surface-active agents: properties; Surfactants; transport; Transport process; Micelle; Aqueous solution; Surfactant; Aggregate; Diffusion; Precursor
• ISSN: 0001-1541; 1547-5905
• DOI: 10.1002/aic.10065

A strategy for accelerating the rate of transport of surfactant within a system by delivering the surfactant as a precursor to the surface‐active state (“prosurfactant”) and subsequently transforming it to a functional form (surfactant) is reported. An increase in the overall rate of transport of a redox‐active surfactant across a polycarbonate membrane containing pores with a diameter of 10 nm is demonstrated. This redox‐active molecule, which is molecularly dispersed in aqueous solutions in its oxidized state (prosurfactant), but assembles into globular micellar aggregates (Rh = 5 nm) in its reduced state (surfactant), was rapidly transported across the membrane in its oxidized state to a concentration of 0.2 mM. Subsequent delivery of ascorbic acid (a reducing agent) by diffusion through the same membrane led to reduction of the oxidized precursor and formation of surfactant and micelles. The sequential delivery of the prosurfactant and then transforming agent resulted in a greater than sixfold increase in the overall rate of delivery of surfactant as compared to a procedure in which the surfactant was diffused across the membrane. These observations are compared to calculations based on hindered diffusion through cylindrical pores. © 2004 American Institute of Chemical Engineers AIChE J, 50: 708–714, 2004