Current Phenomenological Know-How and Modeling of Emulsion Inversion

Abstract

This paper encompasses classic trends as well as recent advances in the understanding of emulsion inversion phenomena. The generalized formulation issue is first discussed from hydrophilic−lipophilic balance to the most recent concepts. The so-called standard inversion line on the formulation−composition map exhibits several branches, referred to as transitional and catastrophic inversions, that bound normal and abnormal emulsion regions. Dynamic inversion is also discussed with its hysteresis zones, where both types of emulsions may be attained, depending upon the system's previous history of the formulation−composition map. Recent findings are reported concerning the effect of variables with practical relevance (i.e., stirring energy, viscosity of phases, surfactant concentration, and partitioning) on the standard and dynamic inversion patterns. State-of-the-art emulsion inversion modeling is briefly discussed.

Ionic Liquids as Surfactants – Applications as Demulsifiers of Petroleum Emulsions

“…The minimum emulsion stability occurs when the HLD equals zero. The HLD is the dimensionless version of the SAD (surfactant affinity difference) and developed by Salager and coworkwers [29][30][31][32].…”

Phase inversion of polyacrylamide‐based inverse‐emulsions: Influence of inverting‐surfactant type and concentration

“…Emulsion inversion applied to basic water-in-oil or oilin-water type emulsions has been widely studied by Salager, [3][4][5] Brooks, [6][7][8] and Dickinson. 9,10 Phase inversion in emulsions was divided into two different mechanisms, depending upon the path of inversion: transitional inversion and catastrophic inversion.…”

“…13 This can be controlled by changing the salinity of the water, for example, by varying the concentration of sodium chloride. It is thought that salinity may affect lipophilicity (hydrophilicity) by modifying the surfactant-solvent affinity 5 and thus the inversion efficiency. The inversion process may be further influenced by controlling the hydrodynamics of mixing of the polymer-emulsion with excess water containing an inverting agent.…”

“…(A2) have been reported; 5,16 however, it is not our purpose to include these here and they will not be discussed further. The present approach points out that, in the vicinity of the optimum formulation, the effect of formulation differences may be described by a unique metricthe surfactant-affinity difference.…”

Hysteresis behaviour in temperature‐induced emulsion inversion

“…[1][2][3] A change in any of these variables can induce emulsion inversion. It is well known that variation of the waterto-oil ratio (WOR) generates a so-called catastrophic inversion, 4 which in most cases, exhibits a delayed inversion with respect to the standard inversion, ie the boundary between the regions where the two types of emulsions are attained upon stirring equilibrated systems.…”