Influence of surfactant on gas bubble stability

Area of Science:

• Physical Chemistry
• Surface Science
• Chemical Engineering

Background:

• Gas bubble stability is crucial in various industrial processes.
• Insoluble surfactants are known to reduce gas-liquid interfacial permeability, enhancing bubble stability.
• The effect of soluble surfactants on interfacial mass transfer remains less understood.

Purpose of the Study:

• To investigate the impact of soluble surfactants on gas-liquid mass transfer.
• To compare the effects of soluble and insoluble surfactants on gas bubble stability and dissolution.

Main Methods:

• Developed an experimental system to measure carbon dioxide (CO2) absorption and desorption rates.
• Utilized a quiescent planar interface with dodecyl trimethylammonium bromide (a soluble surfactant).
• Observed gas bubble dissolution in the presence of soluble (dodecyl trimethylammonium bromide) and insoluble (stearic acid) surfactants.

Main Results:

• Soluble surfactants showed no measurable reduction in CO2 desorption or absorption rates.
• Absorption experiments indicated an unexpected mass transfer mechanism involving surface renewal.
• Gas bubbles with soluble surfactants dissolved completely, while those with insoluble surfactants persisted.

Conclusions:

• Soluble surfactants offer significantly lower resistance to interfacial mass transfer compared to insoluble ones.
• Dynamic adsorption/desorption of soluble surfactants creates temporary vacancies, facilitating unrestricted gas transfer.
• Insoluble surfactants, like stearic acid, increase bubble stability by forming compressed monolayers at the interface.