Carbon dots decorated cadmium sulfide nanomaterials for boosting photocatalytic activity for ciprofloxacin degradation.

This study investigates the utilization of carbon dots (CDs) from neem leaves (Azadirachta indica) decorated onto cadmium sulfide (CdS) for the photocatalytic degradation of ciprofloxacin. A comparative study of ciprofloxacin degradation with pristine CdS and CD decorated CdS demonstrated high degradation of ∼ 75 % with CD/CdS when compared to bare CdS (∼68 %). Process optimization studies were further carried out with CD/CdS catalysts at different solution pH (4-10), feed concentrations (10-50 mg/L), catalyst loadings (25-125 mg/L), temperatures (10 - 30 °C), and lamp power (25, 50, 250 W and sunlight). Higher temperatures, combined with a solution pH of 7 and catalyst loading of 100 mg/L favored the enhanced degradation of 20 mg/L of ciprofloxacin. The ciprofloxacin degradation rate increased linearly with temperature with an apparent activation energy of 27 kJ mol-1. The CD/CdS photocatalyst demonstrated maximum degradation rates with higher lamp powers while it also showed remarkable performance under natural sunlight achieving the same degradation within 3 h.