Environmental applications of flame synthesized CuO nanoparticles through removal of Congo Red dye

Abstract

The Copper oxide (CuO) transition metal oxide nanoparticles (NPs) synthesized by simple, fast and commercially viable comfortably slight modified flame pyrolysis method. The CuO NPs were synthesized by direct burning of ethanolic copper chloride solution. The prepared CuO NPs were characterized for phase and crystallinity by X–ray Diffraction [XRD] and Fourier Transform Infrared [FT–IR] Spectroscopy, estimation of morphology was done by Field Emission Transmission Electron Microscopy [FE–SEM], average particles size of prepared CuO NPs estimated by High Resolution Transmission Electron Microscopy [HR - TEM] as well purity ensured by Energy Dispersive X–Ray Spectroscopy [EDS]. UV–vis absorption spectroscopy done for adsorption of aqueous Congo Red (CR) dye of flame synthesized CuO NPs. The structural, elemental and morphological characterization emphasised the synthesized CuO NPs are crystalline, pure and exhibited monoclinic structure with spherical morphology. The environmental applications of these flame synthesized CuO NPs were also evaluated by using adsorption of Congo Red (CR) dye and temperature effect on dye adsorption were also verified. HR-TEM revealed the average particles size of around 30 nm with fringe spacing of 2.788 Å and 2.377 Å, which corresponds to (110) and (200) planes of monoclinic phase of CuO NPs. The synthesized CuO NPs exhibited optical bandgap of 2.93 eV. The synthesized NPs showed high dye removal capacity up to 99.90% for the aqueous solution of Congo Red azo dye. These CuO NPs may emerge as the best catalytic adsorption alternative for the removal of industrial dyes, heavy metals and waste water treatment.