Solubilization of TX-100™ and PEG-PPG-PEG in Liquid Carbon Dioxide

Abstract

Carbon dioxide (CO₂) at the subcritical, near-critical, and supercritical states has been found to be a powerful solvent with tunable characteristics. It is currently considered an alternative solvent to the conventional organic solvents and has attracted numerous industrial activities (processes). However, CO₂ has been limited in its application due to challenges with dissolving polar macromolecules, which limits its applications. This article presents the solubilization of surfactant; octylphenol ethylene oxide (TX-100™) and poly(ethylene glycol)-block-poly (propylene glycol)-block-poly (ethylene glycol) (PEG-PPG-PEG) in liquid carbon dioxide. The TX-100™ is solubilized in the liquid CO₂ in a programmable phase equilibrium analyzer at varying temperatures and pressures. The emulsion characteristics as well as the water capacity of TX-100™ and PEG-PPGPEG each in liquid CO₂ is predicted by using ethyl acetate as substituted solvent. For PEG-PPG-PEG and TX-100™ emulsion systems, microemulsion form at water-to-surfactant volume ratios of less than 1.0 and 1.2 with their corresponding liquid CO₂ volume of greater or equal to 94% and 94.6%, respectively.

Keywords:

• liquid and supercritical co₂
• microemulsion
• miniemulsion
• near critical fluids
• reverse micelles
• surfactants

ACKNOWLEDGEMENTS

This article was prepared with the support of National Science Foundation (NSF) Science and Technology of Environmentally Responsible Solvents and Processes under Cooperative Agreement CHE-9876674. However, any opinions, findings, and conclusions, or recommendations expressed herein are those of the authors and do not necessarily reflect the views of the NSF. The authors also express their appreciation to the Kenan Center for the Utilization of Carbon Dioxide in Manufacturing at the North Carolina State University for using their phase equilibrium analyzer.

Notes

*Currently with Hobart Corporation, 701 S. Ridge Avenue, Troy, OH 45374.