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Interfacial Rheology Measured with a Spinning Drop Interfacial Rheometer: Particularities in More Realistic Surfactant–Oil–Water Systems Close to Optimum Formulation at HLD N = 0
Author(s) -
Marquez Ronald,
Meza Luz,
Alvarado José G.,
Bullón Johnny,
Langevin Dominique,
Forgiarini Ana M.,
Salager JeanLouis
Publication year - 2021
Publication title -
journal of surfactants and detergents
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.349
H-Index - 48
eISSN - 1558-9293
pISSN - 1097-3958
DOI - 10.1002/jsde.12502
Subject(s) - pulmonary surfactant , rheometer , rheology , chemistry , surface tension , chemical engineering , emulsion , demulsifier , ethylene oxide , viscosity , spinning drop method , cyclohexane , drop (telecommunication) , thermodynamics , chromatography , organic chemistry , composite material , materials science , polymer , biochemistry , physics , engineering , copolymer , telecommunications , computer science
Three different cases were selected to study the effect of physicochemical formulation on interfacial rheology properties of surfactant–oil–water (SOW) systems by increasing the complexity of the system from a basic case. This was performed by changing the normalized hydrophilic–lipophilic deviation (HLD N ) to attain the optimum formulation at HLD N = 0. Two types of SOW systems were studied: the first one used an ionic surfactant with a salinity scan, and the second one a mixture of two nonionic surfactants in a formulation scan produced by changing their proportion. Both of them contained cyclohexane as a pure oil phase, without alcohol. Sec‐butanol was then added as a co‐surfactant with hardly any formulation influence on HLD N . The complexity in interfacial rheology was then increased by changing the oil to a light crude with low asphaltene content. The interfacial rheology is also reported for a realistic system with a high asphaltene content comprised of crude oil diluted in cyclohexane with a conventional surfactant and a commercial demulsifier. The findings confirm that at optimum formulation and whatever the scanning variable (salinity, average ethylene oxide number in the nonionic surfactant mixture, or surfactant/demulsifier concentration), the interfacial tension, and interfacial elastic moduli E , E ′, and E ″ exhibit a deep minimum. These observations are related to the acceleration of the surfactant exchanges between the interface, oil, and water, near the optimum formulation. Several arguments are put forward to explain how these findings could contribute to the decrease in emulsion stability at HLD N = 0.