title: Oxygenated hydrocarbon ionic surfactants exhibit CO2 solubility.
abstract: Several oxygenated hydrocarbons, including acetylated sugars, poly(propylene glycol), and oligo(vinyl acetate), have been used to generate CO2-soluble ionic surfactants. Surfactants with vinyl acetate tails yielded the most promising results, exhibiting levels of CO2 solubility comparable to those associated with fluorinated ionic surfactants. For example, a sodium sulfate with single, oligomeric vinyl acetate (VAc) tails consisting of 10 VAc repeat units was 7 wt % soluble in CO2 at 25 degrees C and 48 MPa. Upon introduction of water to these systems, only surfactants with the oligomeric vinyl acetate tails exhibited spectroscopic evidence of a polar environment that was capable of solubilizing the methyl orange into the CO2-rich phase. For example, a single-phase solution of CO2, 0.15 wt % sodium bis(vinyl acetate)8 sulfosuccinate, and water, at water loading (W) values ranging from 10 to 40 at 25 degrees C and 34.5 MPa, exhibited a methyl orange peak at 423 nm. This result indicated that the core of a reverse micelle provided a microenvironment with a polarity similar to that of methanol. Quantum chemical calculations indicate that the acetylated sugars may be too hydrophilic to readily form reverse micelles, whereas the VAc-based surfactants appear to have the correct balance of hydrophilic and hydrophobic forces necessary to form reverse micelles.
authors.affiliation: Department of Chemical Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA.
authors.forename: Xin
authors.initials: X
authors.lastname: Fan
authors.forename: Vijay K
authors.initials: VK
authors.lastname: Potluri
authors.forename: M Chandler
authors.initials: MC
authors.lastname: McLeod
authors.forename: Yang
authors.initials: Y
authors.lastname: Wang
authors.forename: Juncheng
authors.initials: J
authors.lastname: Liu
authors.forename: Robert M
authors.initials: RM
authors.lastname: Enick
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Hamilton
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Roberts
authors.forename: J Karl
authors.initials: JK
authors.lastname: Johnson
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Beckman
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry*; D006838:Hydrocarbons / Q000737:chemistry*; D008956:Models, Chemical; D015394:Molecular Structure; D010100:Oxygen / Q000737:chemistry; D012995:Solubility; D013501:Surface-Active Agents / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D006838:Hydrocarbons; D013501:Surface-Active Agents; D002245:Carbon Dioxide; D010100:Oxygen