Dispersion of oil into water using lecithin-Tween 80 blends: The role of spontaneous emulsification

David A. Riehm, David J. Rokke, Prakash G. Paul, Han Seung Lee, Brent S. Vizanko, Alon V. McCormick

Research output: Contribution to journalArticlepeer-review

40 Scopus citations

Abstract

Lecithin-rich mixtures of the nontoxic surfactants lecithin and Tween 80 are effective marine oil spill dispersants, but produce much higher oil-water interfacial tension than other, comparably effective dispersants. This suggests interfacial phenomena other than interfacial tension influence lecithin-Tween 80 dispersants’ effectiveness. The interface between seawater and dispersant-crude oil mixtures was studied using light microscopy, cryogenic scanning electron microscopy, and droplet coalescence tests. Lecithin:Tween 80 ratio was varied from 100:0 to 0:100 and wt% dispersant in the oil was varied from 1.25 to 10 wt%. Tween 80-rich dispersants cause oil-into-water spontaneous emulsification, while lecithin-rich dispersants primarily cause water-into-oil spontaneous emulsification. Possible mechanisms for this spontaneous emulsification are discussed, in light of images of spontaneously emulsifying interfaces showing no bursting microstructures, interfacial gel, or phase inversion, and negligible interfacial turbulence. Dispersant loss into seawater due to oil-into-water spontaneous emulsification may explain why Tween 80-rich dispersants are less effective than lecithin-rich dispersants with comparable interfacial tension, although longer droplet coalescence times observed for Tween 80-rich, self-emulsifying dispersant-oil mixtures may mitigate the effects of dispersant leaching. Conversely, surfactant retention in oil via lecithin-rich dispersants’ water-into-oil emulsification may explain why lecithin-Tween 80 dispersants are as effective as dispersants containing other surfactant blends which produce lower interfacial tension.

Original languageEnglish (US)
Pages (from-to)52-59
Number of pages8
JournalJournal of Colloid And Interface Science
Volume487
DOIs
StatePublished - Feb 1 2017

Bibliographical note

Publisher Copyright:
© 2016 Elsevier Inc.

Keywords

  • Crude oil
  • Dispersant
  • Lecithin
  • Spontaneous emulsification
  • Surfactants

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