Effect of the polar modifiers on supercritical extraction efficiency for template removal from hexagonal mesoporous silica materials: Solubility parameter and polarity considerations

Abstract

The introduction of polar modifiers usually can make supercritical CO2 extraction more attractive in various potential applications. In this work, modified supercritical CO2 extraction of the dodecylamine template has been performed on freshly synthesized mesoporous HMS materials with the use of 10 different polar modifiers. The effects of the polar modifiers on the extraction efficiencies of the amine template and structural properties of resultant HMS materials have been investigated in detail. Among the ten modifiers used, formic and acetic acids, water and methanol give reasonably high extraction efficiencies and the effects of the modifier identity on extraction efficiencies have been discussed in terms of solubility parameter and dipole moment of the modifiers. Methanol seems to be much better than the other modifiers for the SCCO2 extraction of dodecylamine from HMS materials since the resulted materials have well preserved highly ordered mesoporous structure and possessed much large specific surface area and pore volume as reflected by XRD spectra and nitrogen adsorption/desorption results.