Stevia rebaudiana leaf extract mediated green synthesis of cerium oxide nanoparticles for antibacterial activity and photocatalytic degradation of tetracycline

Cerium oxide nanoparticles (CeO 2 -NPs) are multifunctional oxide metal nanoparticles that have been considered by many due to their unique properties, including antimicrobial, antifungal, semiconducting, and photocatalytic activity. In this research, CeO 2 -NPs were synthesized using a natural sweetener glycoside in the aqueous crude extract of Stevia rebaudiana that acted as an excellent bio-reductant. The prepared nanoparticles were further characterized by Raman spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and field emission -scanning electron microscopy (FE-SEM). The FE-SEM results confirmed that the CeO 2 -NPs were nano -size (10-50 nm). The antibacterial activity of CeO 2 -NPs against Pseudomonas aeruginosa and Enterococcus faecalis has shown that the Minimum Inhibitory Concentration (MIC) was 6.25 and 12.5 mu g/mL and Minimum Bactericidal Concentration (MBC) were 12.5 and 25 mu g/mL respectively. In the presence of CeO 2 -NPs (under optimal conditions: catalyst dosage = 0.75 g/L, TC concentration = 5 mg/L, pH=10), about 80.68% of tetracycline (TC) was degraded after 45 min UV -irradiation that it is indicative of the acceptable photocatalytic property of CeO 2 -NPs.