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

• Template extraction efficiency is strongly dependent on the modifier identity.
• Modifier performance may be explained by the solubility parameter difference.
• Over 85% of amine can be removed by methanol, water, formic and acetic acids.
• Modifiers have strong effects on physical properties of resultant HMS materials.
• Water modifier can induce the material pore collapse as shown by XRD spectra.

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.

Dependence of extraction efficiency and |δS–δmSF| on the 10 modifiers used for 1 h SCCO2 extraction at 65 °C and 15.0 MPa.Figure optionsDownload as PowerPoint slide