Green synthesis of zinc sulfide nanophotocatalysts using aqueous extract of Ficus Johannis plant for efficient photodegradation of some pollutants

Summary In this work, a green and plant-mediated approach based on the aqueous extract of the Ficus Johannis plant was presented for synthesis of zinc sulfide (ZnS), as efficient and eco-friendly nanophotocatalysts (NPCs). In the first phase, after identification, collection, and drying of the plant, the aqueous extract of the plant fruits was prepared by microwave-assisted extraction (MAE) technique. The characterization of the as-prepared ZnS NPCs was carried out by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution scanning electron microscopy (HR-SEM), Fourier-transform infrared spectroscopy (FT-IR), fluorescence, and UV-Vis absorption spectroscopy. The fluorescence and UV-Vis absorption investigations showed an obvious emission peak between 420-440 nm with a broad absorption band between 290-320 nm. From SEM and TEM images, the particle size of the ZnS NPCs was estimated to be smaller than 20 nm. In the next step, the application of the as-prepared ZnS NPCs was examined as for photodegradation of some industrial pollutants including naphthalene (Naph), anthracene (AnT), 4- chlorophenol (4-CP), and 4- nitrophenol (4-NP). The effect of experimental parameters on photodegradation percentage of the pollutants such as NPCs dosage, initial pollutant concentration, UV-irradiation time, scavenger type was studied. Under optimum conditions, high-degradation efficiency was obtained using a low amount of ZnS NPCs, after 120 min UV irradiation. Finally, the probable mechanism of the presented heterogeneous photodegradation approach was discussed, too.