Reusable ZnO/Activated Carbon-Alginate beads for photocatalytic textile dye degradation: Synthesis, efficiency and...

The development of sustainable, efficient, and reusable catalysts is essential for wastewater treatment. This study presents a novel hybrid photocatalyst composed of ZnO nanoparticles and activated carbon (AC) derived from date pits, an abundant, low-cost agrowaste, encapsulated within alginate beads (ZnACAB). The encapsulation enhances reusability, stability, and adsorption capacity. Comprehensive characterization was performed using XRD, FTIR, UV-Vis, Raman, SEM-EDS, BET, and EPR spectroscopy. Photocatalytic activity was evaluated under both UV and natural solar irradiation for the degradation of Basic Yellow 28 (BY28) and Basic Red 46 (BR46), demonstrating a realistic and energy-efficient treatment approach. Under solar light, ZnACAB achieved dye removal efficiencies of 83 % for BR46 and 78 % for BY28 using 15 g.L^-1 of catalyst at ambient pH over 6 h. Reusability tests confirmed high photocatalytic activity over twenty successive cycles. Phytotoxicity and biodegradability analyses validated the improved quality of treated effluents. A cost evaluation of the synthesis and treatment process further demonstrated the economic and environmental viability of ZnACAB. These results highlight the material's strong potential for practical and scalable wastewater treatment applications.