Facile one-step synthesis of Au-ZnO/MWCNTs for photocatalytic treatment of Reactive Blue dye in aqueous solution

Abstract

In this work, the multiwall carbon nanotubes (MWCNTs) based gold-zinc oxide (Au-ZnO) nanocomposite has been synthesized for visible light driven photocatalytic decolorization of reactive blue-4 (RB4) dye. The Au-ZnO/MWCNTs nanophotocatalyst has been successfully synthesized via thermal treatment method at 600 0C. The physico-chemical properties of MWCNTs and Au-ZnO/MWCNTs have been investigated via powder X-ray diffraction (XRD) spectroscopy, UV-visible diffuse reflectance spectroscopy (UV-DRS), Fourier transform infrared spectroscopy (FTIR)scanning electron microscope (SEM), atomic force microscopy (AFM) and transmission electron microscopy (TEM). The synergistic effect of MWCNTs and Au NPs doping could offers an interesting opportunity to design photocatalyst material with the maximum absorption shift to the visible region of the spectrum, where photocatalytic activity can be enhanced. The results exhibited the growth of Au and ZnO nanoparticles (NPs) on the MWCNTs surface with an average diameter of 20 – 30 nm. The photodecolorization of RB4 dye was investigated by changing pH (3-11), dosage of photocatalyst (0.2-1.4 g/L), and initial RB4 concentration (25–100 mg/L). Under best treatment conditions (pH 11 and catalyst dosage 1.0 g/L), the best photodecolorization efficiency was reached 94.91 %. Based to the obtained results, the photodecolorization efficiency adopting Au-ZnO/MWCNTs photocatalyst was stated to be a promising route for remediation the organic pollutants in aqueous solutions