Foam formation and mitigation in a three-phase gas-liquid-particulate system

Area of Science:

• Colloid and Surface Science
• Materials Science
• Chemical Engineering

Background:

• Foaming in three-phase systems (gas-liquid-solid) is a significant industrial challenge, particularly in nuclear waste vitrification.
• Particle surface properties (hydrophilicity, hydrophobicity, biphilicity) are key drivers of foamability and stability.
• Limited literature exists on foam generation by particles without surfactants.

Purpose of the Study:

• To investigate foam generation and stability using amphiphilic particles derived from sodium chloride.
• To understand the role of particle surface modification and concentration on foam properties.
• To explore the correlation between particle adsorption at the air-liquid interface and foamability.

Main Methods:

• Experimental generation of aqueous foams using modified sodium chloride particles.
• Cross-polarized light microscopy to visualize surfactant adsorption on particle surfaces.
• Measurement of foaminess and foam stability as a function of amphiphilic particle concentration.
• Study of amphiphilic particle adsorption at a planar air-water interface.

Main Results:

• Amphiphilic particles, created by surfactant adsorption on sodium chloride, form stable aqueous foams with high air content (>90%).
• These biphilic particles adsorb at the air bubble surface, inhibiting bubble coalescence and enhancing foam stability.
• Foaming power increases with amphiphilic particle concentration, exhibiting a maximum due to competing effects of particle attachment and flocculation.
• Foamability correlates strongly with particle coverage at the air-liquid interface.

Conclusions:

• Amphiphilic particle modification of crystalline solids is an effective strategy for generating and stabilizing foams.
• Particle concentration management is crucial, as high concentrations can lead to flocculation and reduced foamability.
• Understanding particle adsorption at interfaces is vital for controlling foam behavior in industrial processes.