Synthesis of Ag-ZnO Nanocomposite Using Psidium Guajava Leaf Extract and Evaluation of its Photocatalytic Activity

Abstract

The increase of environmental pollutions from industry due to organic dye effluents initiated the researcher to design a nanomaterial with a target of photocatalytic degradation capacity. So, the main objective of this thesis was to synthesize Ag-ZnO NCs using Psidium guajava leaf extracts and evaluate its photocatalytic activity. A simple, ecofriendly, inexpensive, short-time consumer and biocompatibility approach was developed for the synthesis of Ag-ZnO NCs using P. guajava leaf extract without employing any chemical stabilizer. The phytochemical screening analysis of the plant extract confirmed the presence of alkaloids, flavonoids, phenols, tannins and saponins. The synthesized crystalline nanoparticles were characterized by UV-Vis, FT-IR and XRD. The UV-Vis absorbance peak for ZnO and Ag-ZnO were 374 and 375 nm with band gap of 3.02 and 2.86 eV respectively. The FT-IR result showed the presence of functiona groups in the leaf extract and prepared nanoparticles. Furthermore, a good coordination of functional groups with the synthesized NPs were observed as it displayed red-shift of absorbance peaks. The XRD data revealed that the average crystalline size of ZnO and Ag-ZnO were 22 and 26 nm, resperctively. Photocatalytic activity of Ag-ZnO NCs was performed under natural sunlight using methylene blue as organic dye pollutant. The dye was entirely decolorized and degraded by more than 98% after irradiation for 120 min. In contrast, the solar light catalyzed dye was not decolorized still it was irradiated upto 200 min. Therefore, the present study provided that the Ag doped ZnO nanocomposites may have good applications and high-efficiency of photocatalytic activity