Foam Stability in Aqueous Systems Containing an Amino Acid-Based Surfactant and Gelatin: An Interfacial Shear...

Area of Science:

• Colloid and Surface Science
• Materials Science
• Rheology

Background:

• Foam stability is crucial for many industrial applications.
• Interfacial properties significantly influence foam behavior.
• Understanding interfacial rheology aids in designing stable foams.

Purpose of the Study:

• To investigate the role of interfacial shear properties in foam stability.
• To explore the formation of viscoelastic films at the air/solution interface.
• To correlate interfacial gelation with foam stability enhancement.

Main Methods:

• Interfacial shear rheological measurements using a bicone-type geometry.
• Utilized an anionic amino acid-based surfactant and gelatin as foam stabilizers.
• Analyzed interfacial shear storage modulus (G'), loss modulus (G″), and loss tangent (tan δ).

Main Results:

• A viscoelastic film formed at the air/solution interface with the surfactant-gelatin mixture.
• Maximum G' and G″, and minimum tan δ observed at specific concentrations, indicating an elasticity-dominant, gel-like interfacial film.
• Highest foam stability correlated with interfacial gelation, suppressing liquid drainage and bubble coalescence.
• Lower pH enhanced elastic responses, reduced surface tension, and improved foam stability.

Conclusions:

• Interfacial gelation between oppositely charged surfactant and gelatin components enhances foam stability.
• Interfacial shear rheology with bicone geometry is a practical tool for predicting foam stability.
• Findings have implications for optimizing foam performance in diverse industrial applications.