Preparation and characterization of metakaolin-based geopolymer membrane supports by facile pressed one-part route

This study reports on the possibility of applying one-part pressed geopolymers as a support for microfiltration membranes. The mineralogical, physical, mechanical, microstructural and hydraulic properties of the investigated materials are presented. Metakaolin-based geopolymeric membrane flat supports were synthesized by uniaxial pressing a dry-mixed powder (Si/Al = 1.45, Na/Al = 0.9, Na/Si = 0.62, H2O = 12%), with pressure between 2 and 20 MPa and a curing temperature of 70 °C. Mixing and pressing optimization resulted in samples with a total open porosity up to 39%, a modal pore diameter up to 23.5 μm and a flexural strength up to 20.4 MPa. Permeation measurement with demineralized water and ethanol-water solutions were carried out using a dead-end geometry membrane apparatus. A hydraulic permeability up to 31.3·103 L h−1 m−2 bar−1 has been obtained. Furthermore, permeation tests using water-ethanol solutions have demonstrated that the material is hydrophilic. These results highlighted the potential of geopolymers as microfiltration support.