Synthesis and characterizations of Al-doped ZnO photocatalyst for removal dyes

Abstract

The disposal of organic dyes from different processing textile plants imposes series challenges to the environment and therefore to the health of society. Thus, these toxic and environmentally polluting organic dyes have to be amended before discharging them to the environment. In this work, ZnO and Al-doped ZnO photocatalytic materials were synthesized by the sol-gel method for removal of methylene blue (MB) organic dye from textile waste effluent. The phase purity and morphology of the synthesized samples were investigated by using X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM)/Energy dispersive spectroscopy (EDS), respectively. Fourier Transform Infrared (FT-IR) Spectroscopy and UV visible (UV-VIS) spectroscopy were used, respectively, for chemical composition analysis and optical bandgap property measurements. FT-IR result showed predominant absorbance peaks at 864, 712, and 506 cm^-1, which correspond, respectively, to the Al-O, Al-O-Zn, and Zn-O bond stretching. From the absorbance spectra, the optical bandgap energies were calculated and found to be around 3.5, 3.0, 2.5, and 2.4 eV, respectively, for undoped, 0.5 %, 1%, and 2% Al-doped ZnO.  The performance of the photocatalytic materials was investigated against the degradation ability towards the MB dye under different condition in a batch reactor. The 2%Al-doped ZnO exhibited the best performance with about 99 % degradation of MB under a light intensity of 5810 lux and corresponding reaction temperature of 65 °C