Photocatalytic removal of ciprofloxacin in drinking water treatment plant process using nanocomposite BN/TiO2

Abstract In this study, BN/TiO 2 was evaluated for the photocatalytic removal of ciprofloxacin (CIP) under UV irradiation in real water collected from a drinking water treatment plant (DWTP) at the following treatment points: influent, clarifier, and effluent. Comparative photocatalytic experiments were conducted in both synthetic and real water matrices using TiO 2 , BN, and BN/TiO 2 . The optimized parameters were pH 5, CIP concentration 5 mg/L, and photocatalyst dosage 20 mg. The highest removal efficiency of 97.04% was determined under these optimised parameters. BN/TiO 2 outperformed both the synthesized TiO 2 and BN due to synergistic effects arising from strong interfacial contact, which facilitated efficient charge separation, where BN acted as an electron sink. Superoxide radicals (O 2 •− ) were the primary species responsible for CIP photocatalytic removal, with the contribution of the other scavengers in the order: holes > electrons > hydroxyl radicals. The photocatalytic removal efficiencies of CIP using BN/TiO 2 were 69.3%, 83.3%, and 90.2% in the influent, clarifier, and effluent, respectively. Enhanced removal in the effluent was attributed to lower turbidity, which improved light transmission; higher dissolved oxygen that promoted superoxide radical formation; and increased ionic strength, which facilitated charge transport while suppressing electron–hole recombination. One-way ANOVA confirmed that both the operational parameters and the water matrix significantly influenced BN/TiO 2 photocatalytic removal of CIP. These findings position BN/TiO 2 as a promising photocatalyst for DWTP integration, ideally in fixed-bed reactors post-clarifier stage for easy recovery. For practical use, UV-powered BN/TiO 2 system proves most effective between clarifier and disinfection stages under near-neutral pH conditions.