Aggregate-based sub-CMC Solubilization of Hexadecane by Surfactants

Area of Science:

• Colloid and Surface Chemistry
• Environmental Science

Background:

• Surfactants are crucial for solubilizing hydrophobic compounds.
• Understanding surfactant behavior near the critical micelle concentration (CMC) is key for applications.

Purpose of the Study:

• Investigate hexadecane solubilization by SDBS and Triton X-100 below CMC.
• Characterize the aggregation behavior of these surfactants at low concentrations.

Main Methods:

• Solubilization experiments with hexadecane.
• Dynamic Light Scattering (DLS) for aggregate size analysis.
• Cryogenic Transmission Electron Microscopy (TEM) for aggregate visualization.
• Zeta potential measurements.

Main Results:

• Hexadecane solubilization observed below CMC, increasing linearly with surfactant concentration.
• SDBS showed stronger solubilization below CMC compared to above; Triton X-100 showed no difference.
• Aggregate formation below CMC confirmed by DLS and TEM, with aggregate size decreasing as concentration increased.
• Zeta potential behavior differed between SDBS and Triton X-100 aggregates.
• Surface excess calculations indicated significant impact of surfactant molecules on aggregate surface curvature.

Conclusions:

• Surfactant aggregates form below CMC, facilitating hexadecane solubilization.
• Low-concentration surfactant strategies show promise for remediating hydrophobic organic compound (HOC) contaminated sites.