Bismuth Upconversion Luminescent Glass for Fluoride Removal and Photocatalytic Performance of the Fluoride Removal Products
Fluoride-containing wastewater treatment typically relies on calcium-based precipitation and flocculation, which suffer from low compliance rates and difficult valorization of fluoride-laden sludge. This study introduces a novel bismuth upconversion luminescent glass (BULG) synthesized from Bi2O3, SiO2, Yb2O3, and Er2O3, designed for efficient fluoride removal and subsequent photocatalytic application. By varying the Bi2O3:SiO2 molar ratio, a series of BULGs with superior upconversion luminescence were obtained. Under optimal conditions (Bi3+:F− molar ratio = 1:1, pH = 2), fluoride removal efficiencies exceeded 97% for all compositions, with the 0.7:0.3 Bi2O3:SiO2 formulation achieving 99.9% removal and rapid settling of the precipitate. The fluoride removal products retained upconversion luminescence and exhibited semiconductor heterojunctions, enabling complete photocatalytic degradation of ciprofloxacin (100% within 60 min). This approach not only efficiently removes fluoride ions but also valorizes the waste into a functional photocatalyst, offering a promising strategy for fluoride-containing wastewater treatment.