Abstract
Foams produced from non-aqueous media are less common than water-based foams but they play an important role in many industries and engineering processes. The low surface tension of hydrocarbon fluids limits the adsorption of common surface activity substances and different compounds and methods must be considered to generate and stabilize oil-based foam. Likewise, the destruction of unwanted non-aqueous based foam requires specific considerations not found with aqueous systems. Of particular interest are petroleum-based foams, which are highly complex due to the wide variety of compounds and gases that can be found. We provide an overview of the major mechanisms known to be important for non-aqueous foam stability with a spotlight on crude-oil foams.
Highlights
Foams are an example of two-phase media where gas is dispersed throughout a continuous fluid or solid phase
-called solid foam is in some respects a subset of liquid foam as before solidification the continuous phase is in a fluid state during foam generation
For example the surface tension will determine the energy required to create a bubble in the media, and the foaming liquid rheology controls the drainage and approach between adjacent bubbles [3, 5, 6]
Summary
Foams are an example of two-phase media where gas is dispersed throughout a continuous fluid or solid phase. For example the surface tension will determine the energy required to create a bubble in the media, and the foaming liquid rheology controls the drainage and approach between adjacent bubbles [3, 5, 6] Beyond these general concepts more specific physical chemical aspects must be addressed to understand individual systems. Two types of foam can be identified: short-lived foam whose stability is determined by the drainage rate between adjacent bubbles (e.g. champagne foam) and long-lived foam, which relies on energy barriers that prevent bubble coalescence and coarsening (e.g. beer foam) [3, 14] In both systems, the dominant factor is adsorption of surface-active material to the gas-solution interface [15]. Blazquez et al / Non-Aqueous and Crude Oil Foams of hydrocarbon-based fluid foams with focus on foams related to the petroleum industry
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