Advantages and limitations of different methods to determine the optimum formulation in surfactant–oil–water systems: A review

Abstract

The optimum formulation in a surfactant–oil–water (SOW) system is defined as the physicochemical situation at which the surfactant adsorbed at the interface exhibits exactly equal interactions for both oil and water. Identifying the optimum formulation of SOW systems is crucial in various industrial applications, ranging from pharmaceuticals to cosmetics and to petroleum issues like dehydration and enhanced oil recovery. Multiple techniques are available to identify the optimum formulation, often with its own advantages and limitations. In this comprehensive review, we provide an in‐depth analysis of the systematic use of formulation scans to identify the optimum formulation in SOW systems. We critically assess different methods, including conventional ones, such as phase behavior observation, determination of the minimum interfacial tension from equilibrated systems, and the localization of the minimum emulsion stability using formulation scans. We also mention a new promising technique that can be applied in practice, such as oscillating spinning drop interfacial rheology (OSDIR) as well as others that allow an understanding of some structural features of the domains present in the surfactant‐rich phase in SOW systems. Among these methods, dynamic light scattering (DLS), small angle scattering (SAXS and SANS), nuclear magnetic resonance (NMR), X‐ray microcomputed tomography (Micro‐CT), and differential scanning calorimeter (DSC), can be found in the literature. Finally, we discuss potentially unusual behaviors that can appear in complex systems, thus providing guidance on the selection of the most suitable method tailored to the specific application.

Enhancing Oil-Uptake Efficiency with an Alkyl Polyglycoside–Dodecanol Formulation

“…The quantity of oil retained before reaching the Winsor III microemulsion phase is considered the maximum oil uptake, aligning with the optimized formulation concept introduced for enhanced oil recovery (EOR) [79]. It is well established that the optimal formulation corresponds to a minimum interfacial tension, described when the hydrophilic-lipophilic deviation (HLDN) equals zero [80][81][82], indicating the Winsor III phase [83]. In our case, Winsor III is achieved at a volume ratio of 2:0.300 for the CG1C sample (Figure 5H), but it is not observed for the corresponding sample without C12OH, CG1 (Figure 5D).…”

New Trends in Biosurfactants: From Renewable Origin to Green Enhanced Oil Recovery Applications

“…In general, HLB only works in the case of ethoxylated surfactants. For other types of surfactants, a different concept that takes into account parameters such as the oiliness of the surfactant, temperature, salinity, and water is needed [ 141 ].…”

Meta-Analysis and Analytical Methods in Cosmetics Formulation: A Review

“…Since the early 20th century studies by Bancroft, it has been recognized that, generally, the external phase of an emulsion, whether water or oil, depends on the location of the surfactant within one of the phases. Later, Winsor, in 1954, proposed a relationship (so-called Winsor R) through which the interaction energies between the surfactant, water, and oil can be analyzed conceptually, thereby allowing an understanding of the physicochemical situation of the system [119]. The physicochemical formulation of a system is associated with the type of emulsion and its stability.…”

“…The effect of these contraction forces gives rise to interfacial tension, enabling the interface to be stable and adopt geometries which minimize the interfacial area [113]. The details on the measurement of interfacial tension can be found in a recent review on the subject [119]. During the design of cosmetic products, evaluating surface or interfacial tension is crucial.…”

“…The HLD (hydrophilic-lipophilic deviation) model, which considers a surfactant, the oil phase, the aqueous phase, temperature, and even pressure, is a semiempirical expression that allows to characterize the physicochemical situation of a system, with a surfactant contribution parameter (i.e., SCP, also called PACN, sigma or beta). Recent works have extensively outlined the use of the HLD equation for formulations in cosmetics, emphasizing the importance of its use in systems incorporating biobased raw materials [119,146,147,152,153].…”