Role of fabrication parameters on microstructure and permeability of geopolymer microfilters

A new method for preparing geopolymer filtrations was suggested, using silica fume in an alkali activator as an environmentally and economically sustainable material. The geopolymer filtration was fabricated by activating metakaolin with a blend of sodium hydroxide and silica fume. Different phase structures and microstructures were fabricated with varying preparation parameters, such as silica fume content, Na₂O/Al₂O₃ molar ratios, and curing temperatures. The filters were characterized using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersion spectroscopy, and mercury intrusion porosimetry. Filters were tested for pure water flux, compressive strength, and wastewater permeability using industrial textile wastewater. The geopolymer-zeolite composite filter, including 10 wt% silica fume, Na₂O/Al₂O₃ molar ratio of 1, and curing temperature of 60 °C exhibited the highest pure water permeability of 144 L/m².h.bar, wastewater permeability of 77 L/m².h.bar, and achieved 95.5 % turbidity reduction for the textile wastewater.