Eco-Friendly Ceramic Membranes from Natural Clay and Almond Shell Waste for the Removal of Dyes and Drugs from Wastewater

This study investigates the influence of sintering temperature (850-950 °C) and almond shell content (2-10 wt.%) on the structural, mechanical, and functional properties of natural-clay-based ceramic membranes. Several membranes were prepared by incorporating different proportions of almond shell powder and 2 wt.% lime as additives and sintered under controlled thermal conditions to optimize their performance. The results demonstrate that both sintering temperature and almond shell content significantly affect membrane porosity, mechanical strength, and water permeability. Among all of the tested samples, the membrane designated MP2-900, composed of natural clay, 2 wt.% almond shell powder, and 2 wt.% lime, sintered at 900 °C, exhibited the most balanced performance. It showed high mechanical strength (≈28 MPa), low shrinkage (-1·m-2·bar-1). When tested for the removal of crystal violet (CV) dye and paracetamol (PCT) from synthetic wastewater, the MP2-900 membrane achieved a removal efficiency of 87% for both pollutants. Overall, the MP2-900 membrane represents the optimal configuration, providing an excellent balance between mechanical robustness, porosity, and separation performance. These findings highlight the potential of sustainable clay-based ceramic membranes derived from agricultural by-products for the efficient removal of recalcitrant pollutants from wastewater.