Biosynthesis of the ZnO/SnO2 nanoparticles and characterization of their photocatalytic potential for removal of organic water pollutants

• Viscum album ethanol extracts have high levels of phenolic, flavonoid, and antioxidant activity. • A cheap and simple method for the synthesis of ZnO/SnO 2 green nanoparticles was performed. • The ZnO/SnO 2 green nanoparticles exhibited greatly increased visible-light photocatalytic efficiency. • The mechanism for the increased photocatalytic activity of ZnO/SnO 2 green nanoparticles was propounded. • Efficient photoactivity and high stability were obtained for organics pollutant degradation. Plants are rich sources of antioxidant compounds including phenols and flavonoids. These antioxidants are crucial elements in diet and protect the body against oxidative stress. In this study, antioxidant activity of the phenolic compounds and flavonoids of mistletoe ( Viscum album ), as a substituent for synthetic antioxidants, was quantitatively investigated. The plant alcoholic (ethanol) extract was used for biosynthesis of the ZnO/SnO 2 composite nanoparticles that were employed for photodegradation of three organic pollutants (Congo red (CR), Biphenyl A (BPA), and tetracycline (TC)) under solar light. The photodegradation tests were performed considering the effect of pH, photocatalyst dosage, temperature, and initial concentration of the pollutants. The obtained data were analyzed by a Pseudo-first-order kinetic model. The most optimum conditions for photodegradation of the organic pollutants were found to be: 5 mg/l initial pollutant concentration, 0.5 g/l photocatalyst dosage, and acidic pH. The reusability test implied that the nanoparticles remain stable and can perform well even after 4 cycles of reuse. Conclusively, Viscum album extract offers promising antioxidant properties and allows for biosynthesis of the composite nanoparticles that can optimally photodegrade organic pollutants of wastewater under solar light.