Hydrocarbon metallosurfactants for CO2

Area of Science:

• Materials Science
• Supramolecular Chemistry
• High-Pressure Chemistry

Background:

• Transition metal surfactants are crucial for various chemical processes.
• Solubility of hydrocarbon surfactants in dense CO2 is often limited.
• Developing novel surfactants for CO2 applications is an active research area.

Purpose of the Study:

• To investigate the solubility of cobalt and nickel salts of a specific trichain anionic surfactant (TC14) in dense CO2.
• To characterize the aggregation behavior of these surfactants in CO2 and other solvents using high-pressure small-angle neutron scattering (HP-SANS).
• To assess the potential of these transition metal surfactants for applications involving CO2.

Main Methods:

• Synthesis and characterization of cobalt and nickel salts of TC14.
• High-pressure solubility measurements in dense CO2.
• High-pressure small-angle neutron scattering (HP-SANS) studies in dense CO2, cyclohexane, and their mixtures.

Main Results:

• Cobalt and nickel TC14 salts demonstrate remarkable solubility in dense CO2, up to 6 wt % at 500 bar.
• HP-SANS reveals the formation of surfactant aggregates in dense CO2, indicating structured behavior.
• The transition metal TC14 derivatives show significant solubility and aggregation in CO2, exceeding typical hydrocarbon surfactants.

Conclusions:

• Transition metal TC14 derivatives are highly soluble in dense CO2, offering a new class of surfactants for this medium.
• These compounds are effective in incorporating functional metal ions into CO2, expanding possibilities for CO2 utilization.
• The study confirms the viability of transition metal TC14 surfactants for advanced applications in supercritical CO2 environments.