Permeation properties of organic compounds from aqueous solutions through hydrophobic silica membranes with different functional groups by pervaporation

• Silica membranes with ethyl, n-propyl, isobutyl, or n-hexyl groups were prepared.
• PV performances for organic aqueous solutions such as EA or MEK were confirmed.
• Organic fluxes can be estimated by using Hansen solubility parameters.

In this work, hydrophobic silica membranes with phenyl groups were prepared by a sol-gel method using phenyltrimethoxysilane (PhTMS) as the silica precursor. The effect of the hydrolysis and condensation reaction of the PhTMS sol on the separation performance by pervaporation (PV) was investigated. To prepare a membrane for separation of ethyl acetate from water, the optimum reaction time for the silica sol was 3 h. Membranes were also prepared under the same conditions using ethyltrimethoxysilane (ETMS), n-propyltrimethoxysilane (PrTMS), isobutyltrimethoxysilane (BTMS), and hexyltrimethoxysilane (HTMS) as the silica precursors. PV was carried out using the ETMS, PrTMS BTMS, and HTMS membranes to separate organic compounds (5% mass fraction) from water at 295 K. The results indicated that the flux of an organic compound was related to the difference between the Hansen solubility parameters of the membrane and that of the organic compound.

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