Highly hydrophobic ceramic membranes applied to the removal of volatile organic compounds in pervaporation

• TiO2, Al2O3 and ZrO2 ceramic membranes were hydrophobized by using fluorosilanes.
• Efficient removal of VOCs was obtained using hydrophobic pervaporation (PV).
• Hydrophobic ceramic membranes were successfully applied for removal of MTBE and EtAc.
• Hydrophobized TiO2 membrane removed VOCs with the highest efficiency.

Highly hydrophobic titania, alumina and zirconia porous ceramic membranes were prepared by grafting of C6F13C2H4Si(OEt)3 (C6) and C12F25C2H4Si(OEt)3 (C12) molecules and subsequently applied in pervaporation (PV) process for removal of volatile organic compounds (methyl tert-butyl-ether/MTBE and ethyl acetate/EtAc) from binary aqueous solutions. Transport of pure water through pristine and hydrophobized membranes were compared. The transport and separation properties in PV process of investigated hydrophobic membranes were discussed. The influence of the membrane materials, pore size of the membranes as well as conditions of the grafting procedure (time and type of molecules) on the pervaporative properties was presented. All investigated membranes were selective toward organic compounds. The highest efficiency was found for the TiO2 membranes, independently of the utilized system and applied grafting molecules. Better transport and selective properties were observed for membrane modified by C6 molecules than by C12 ones. TiO2 and ZrO2 membranes modified by C6 were characterized by high β separation factors 84 (TiO2) and 56 (ZrO2). The least effective membrane was alumina one. Additionally, the influence of contact of different solvents (water, EtAc and MTBE) with the hydrophobic layer was discussed. It was found that in the presence of organic compounds in the aqueous solution, the conformation of hydrophobic chains is changing from tangled to straight one.

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