Photocatalytic degradation of azithromycin using GO@Fe3O4/ ZnO/ SnO2 nanocomposites

چکیده مقاله

Sewage output contains a wide range of organic materials, such as pharmaceutical compounds. These compounds have harmful effects on the environment, such as generation of antibiotic-resistant bacteria; therefore, their degradation has been considered as one of the environmental challenges. The purpose of this research is to synthesize graphene reinforced with nanocomposites of iron oxide/zinc oxide/tin oxide and evaluate its ability to photocatalytic degradation of azithromycin in the aqueous environment. GO@Fe3O4/ZnO/SnO2 nanocomposite was characterized by various techniques including XRD, FT-IR, TEM and VSM. In the batch system, the effect of pH, contact time, catalyst content and initial concentration of azithromycin was investigated; in this system, under optimal conditions of pH = 3, 120 min with 1 g/L of GO@Fe3O4/ZnO/SnO2, 90.06% of 30 mg/L azithromycin were degraded under UV-C irradiation. In the continuous system, the variables of bed height, flow rate and initial concentration of azithromycin have been investigated. The times to reach the column breakthrough point (Cb = 0.02C0) at heights of 6, 8 and 10 cm are 5, 8 and 14 min, respectively. By increasing the height of the bed from 6 to 10 cm, the azithromycin degradation rate increases; the reason for this increase can be due to the increase in contact time. The results indicate that the degradation of azithromycin in a constant bed column strongly depends on these parameters; actually, the time to reach the breaking point decreased with increase of flow rate and initial concentration of azithromycin while increasing with increase of bed height. Estimating the empty bed residence time showed that this model is in good agreement with laboratory data. Therefore, considering the high ability of GO@Fe3O4/ZnO/SnO2 to eliminate azithromycin, this compound can be used as an effective catalyst for the degradation of antibiotics in aquatic environments.