Bridging ceramic engineering and photocatalysis for sustainable water treatment through green solid-casting of TiO2 on alumina-kaolin pellets

Ceramic-based photocatalysts are attracting growing attention for sustainable water treatment, owing to their mechanical stability, chemical resistance, and suitability for immobilized operation. This study introduces a green synthesis approach for fabricating alumina-kaolin ceramic pellets as robust photocatalyst supports. TiO 2 nanoparticles were subsequently immobilized via dip-coating to form TiO 2 @alumina–kaolin composites. Structural characterization revealed a defect-free microstructure with strong necking between alumina and kaolin grains, providing high mechanical integrity and surface accessibility. Photocatalytic activity was evaluated in a fixed-bed photoreactor using mixed organic dyes (Methylene-blue and Rhodamine-B) as model pollutants. The system followed pseudo-first-order kinetics with rate constants of 0.0068 and 0.0019 min -1 , respectively. Operational parameters including dye concentration, pH, contact time, and photocatalyst loading were optimized through response surface methodology. The pellets retained over 85% of activity after five reuse cycles, confirming high durability and recyclability. This solid-casting approach provides a scalable, cost-effective, and environmentally benign route for immobilizing photocatalysts on ceramic supports.