Bismuth Upconversion Luminescent Glass for Fluoride Removal and Photocatalytic Performance of the Fluoride Removal Products

• • Fluoride removal efficiency exceeded 97% for all BULG compositions at Bi3+:F− = 1:1 and pH = 2, with the 0.7:0.3 Bi2O3:SiO2 formulation achieving 99.9% removal, enabling near-complete fluoride elimination in a single step. • • The optimal BULG (0.7:0.3) removed >99% of F− within 10 minutes, demonstrating rapid kinetics suitable for high-throughput industrial wastewater treatment. • • The fluoride removal products contained Bi26O38F2 and BiOF, which formed semiconductor heterojunctions, allowing 100% photocatalytic degradation of ciprofloxacin within 60 minutes, thus converting waste into a valuable photocatalyst. • • The BULG materials retained upconversion luminescence after fluoride removal, enabling potential optical monitoring of the process and adding multifunctionality to the treatment system.