Extraction of surfactants from aqueous media by supercritical fluid extraction

Abstract

Two methods for the supercritical fluid extraction (SFE) of analytes from aqueous media were evaluated: direct extraction and solid-phase extraction (SPE) discs. SPE discs were used to isolate an alcohol phenol ethoxylate (APE) non-ionic surfactant from an aqueous matrix prior to extraction using supercritical CO₂. This method was compared with the direct SFE of surfactant from the aqueous matrix. The second method allowed the continuous extraction of analyte from water using a modified extraction cell. The extraction cell was designed to maximize the exposure of the analyte to supercritical CO₂ interactions and thereby allow the continuous extraction of the analyte from an aqueous sample. The results suggest that there is a difference in the effects of diffusion and equilibrium on the extraction process for the two methods of extraction studied.