Development and characterization of a purified pyrophyllite-based ultrafiltration membrane for the treatment of dye-contaminated water

This study reports the development and optimization of a low-cost ultrafiltration (UF) membrane fabricated from purified pyrophyllite clay for the removal of organic dyes from wastewater. The raw clay, sourced from Morocco, underwent sequential sedimentation, carbonate removal, and organic matter elimination. The purification reduced average particle size from 11.70 to 1.14μm and minimized loss on ignition from 4.25 to 0.07wt%. The optimized membrane produced following clay purification, was sintered at temperatures between 1000 and 1100 °C. Among these conditions, SC1050 membrane (sedimentation and carbonate removal, sintered at 1050 °C) exhibited the best trade-off between permeability and selectivity. It achieved a water permeability of 86Lm-2 h-1 bar-1 and a direct red 80 dye rejection of 91.4%. The membrane also rejected 92.9% of methylene blue (cationic) and 81.4% of Congo red (anionic), indicating performance governed mainly by electrostatic interactions. Fouling tests showed a flux recovery ratio of 89.9% and a low irreversible fouling ratio of 10.1%. Cost analysis estimated the total membrane production cost at USD 14.3m-2, substantially lower than commercial ceramic membranes (USD 500-1000m-2). These findings indicate that purified pyrophyllite is a promising geomaterial for cost-effective and high-performance UF membranes, offering a potentially scalable and sustainable solution for textile wastewater treatment.