Critical-fluid extraction of organics from water. Volume II. Experimental. Final report, 1 October 1979-30 November 1983

Critical fluid extraction has been tested at the pilot plant scale as a method of separating organics from water. The process employed resembles a liquid-liquid extraction in which the solvent is near-critical carbon dioxide and the feed is an organic in aqueous solution. Carbon dioxide's solvent and other thermodynamic properties, and the effective utilization of a vapor recompression cycle in the process design have significantly reduced the energy required for these separations. This process is an energy-conserving alternative to the distillation processes which are currently employed. The objectives of this portion of the project were to demonstrate the feasibility of this technology and to gather the engineering data required to evaluate the process. Three alcohols were tested in these experiments - ethanol, isopropanol and sec-butanol - and were all successfully extracted

An Alpha-Helical Peptide in AOT Micelles Prefers to be Localized at the Water/Headgroup Interface

A model alpha-helical peptide encapsulated in a reverse micelle is used to study the structure and dynamics of proteins under constrained environments that mimic the membrane-water environment in cells. Molecular dynamics simulations of the self assembly of systems composed of a peptide, sodium bis(2-ethylhexyl) sulfosuccinate (AOT), water, and isooctane show that the peptide prefers to be located at the water/AOT headgroups interface. We explore the effect of the AOT headgroup charge and the peptide charge and find that the peptides migrate to the interface in all cases. These results show that the peptides prefer the constrained hydration environment of the AOT headgroups. The driving force for this configuration is the gain in entropy by released water molecules that otherwise would solvate the protein and surfactant headgroup