Studies on transitional emulsion phase inversion using the steady state protocol

• Published in: Colloids and surfaces. A, Physicochemical and engineering aspects Physicochemical and engineering aspects, 2015-11, Vol.484, p.424-433
• Main Authors: Charin, R.M., Araújo, B.C., Farias, A.C., Tavares, F.W., Nele, M.
• Format: Article
• Language: English
• Subjects: Emulsion formulation; Emulsion phase inversion; Phase equilibrium
• ISSN: 0927-7757; 1873-4359
• DOI: 10.1016/j.colsurfa.2015.08.003

[Display omitted] •Emulsion inversion by steady state protocol.•Identification of the frontier between liquid dispersion and emulsion.•Systems in equilibrium and emulsified can present different phase behavior.•Bancroft validity depending on experimental protocol. This study investigated the inversion process in emulsions by the steady state emulsification protocol. Two model systems were tested. The first system contained sodium dodecyl sulfate (SDS)+n-pentanol/toluene+heptane/water+sodium chloride. Phase equilibrium data guided emulsion inversion processes. Salinity and cosurfactant composition were the manipulated variables to emulsions reach the expected phase transitions. Results evidenced different phase behaviors when comparing systems of same formulation in thermodynamic equilibrium and emulsified (expanded area). Systems with WOR different than 1 and low surfactant content systems show prominent difference in phase behavior. A frontier between liquid dispersion and emulsion was scrutinized by increasing the surfactant content. The other investigated system here was composed of poly-ethoxylated nonylphenol/heptane+toluene/water+sodium chloride. It was inverted using a dynamic phase inversion temperature (PIT) procedure. This dynamic emulsion inversion was a reference to achieve the steady state inversion protocol, which consisted of adding solutions for change the mean hydrophilic characteristic of surfactant mixture.