Ceramic-like membranes without sintering via alkali activation of metakaolin, blast furnace slag, or their mixture: Characterization and cation-exchange properties

Alkali-activated (or geopolymer) membranes have emerged recently as an alternative for conventional ceramic membranes. Their main benefit is the simple and low-energy manufacturing not requiring sintering, thus potential clearly lower costs, while having largely similar performance materials. In this work, metakaolin, blast furnace slag, their mixture (representing typical low, high, medium Ca-content raw materials, respectively) were compared aluminosilicate precursors preparation of self-supporting membrane disks (diameter 75 mm, height 3 mm). A thorough material characterization was performed to evaluate mechanical strength, shrinkage, microstructure, chemical composition, pore size distribution, specific surface area, zeta potential, water flux at different temperatures (20–60 °C) pressures (200–1000 kPa). Based on screening, metakaolin-based (i.e., low-calcium system) indicated overall better than two others based slag or mixture. As a final part study, ammonium-containing model effluent ([NH4+] = 50 mg L−1) distributed through (using 200 kPa pressure 25 nitrogen removal recovery. The mass balance examination that ammonium retained in matrix concentrated retentate fraction), likely mechanism via ion-exchange. obtained results provide interesting insights further development alkali-activated applications removal, such bioreactors municipal wastewater treatment.