Application of Ag, N-TiO2 nanomaterial for the photocatalytic control of harmful cyanobacterial cells

In this work, Ag– and N– modified TiO2 photocatalysts were synthesized via a solvothermal method and characterized to evaluate their photocatalytic performance toward cyanobacterial inactivation and microcystin-LR degradation. The modified materials exhibited reduced band-gap energies of 3.00 eV (N–TiO2), 2.45 eV (Ag–TiO2), and 2.17 eV (Ag, N–TiO2) indicating enhanced visible-light absorption. Photocatalytic treatment of Microcystis aeruginosa (∼106 cells mL-1) at catalyst dosage of 0.3 g L-1 showed high removal efficiencies of 89.1 ± 0.9 – 96.3 ± 0.1% under UV light (365 nm) and 81.8 ± 1.7 – 95.0 ± 1.0% under visible light. Ag, N–TiO2 exhibited the highest activity and achieved complete MC-LR degradation within 16 h. Both cyanobacterial inactivation and MC-LR degradation were consistent with the Hom kinetic model, suggesting the combined contributions of photolysis and adsorption. A tentative MC-LR degradation pathway under UV irradiation was proposed based on ESI–MS analysis. The enhanced photocatalytic performance is attributed to the synergistic effects of nitrogen modification and Ag deposition, which improve visible-light absorption, facilitate charge separation, and promote hydroxyl radical generation. These findings highlight the potential of Ag, N–TiO2 photocatalysis for controlling cyanobacterial blooms and associated toxin contamination in water.