Industrial dye removal using bio-synthesized Ag-doped ZnO nanoparticles

Abstract

This contribution reports on the bioremediation of the industrial textile effluent by the valorization of agro-waste extracts of Rosmarinus officinalis (rosemary) leaves using biosynthesized Ag-doped ZnO nanoparticles (NPs), as photocatalysts. Characterization of the NPs was carried out using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), UV-Visible, photoluminescence (PL), and efficacy in the photocatalytic degradation of dyes in non-synthetic industrial textile effluent. FESEM and XRD results depicted the hexagonal structure of the Ag-doped ZnO NPs with the average particle size of 21.65 ± 0.25 nm for FESEM, in the range of 7.450-38.611 nm from Scherrer equation and 28.946 ± 0.002 nm from the Williamson-Hall plot for XRD. EDS indicated Ag (3.94%), Zn (41.01%), and O (30.52%) atoms in the sample, and the carbon (24.53%) attributed to the phenolic compounds in the plant extract, while ATR-FTIR identified stretching vibration mode of Ag-O and Zn-O at 476 cm−1 and 840 cm−1, respectively. From UV-Vis-NIR, the energy bandgap has amounted to 3.23eV and the photoluminescence emission spectrum indicated the existence of surface defects and oxygen vacancies. Synthesized NPs were used for the treatment of the industrial textile effluent (TE) by assessing the pH and temperature, total suspended solids (TSS), biochemical oxygen demand after 5 days (BOD), chemical oxygen demand (COD). The mineralization thus decontamination of the TE has been confirmed with 63 % degradation of the dye being observed after 100 min visible light exposure. The analyses reported herein indicated that this plant extract synthesized nanoparticles can play an important role in the bioremediation of textile industry wastewater.