Treatment of textile wastewater under visible LED lamps using CuO/ZnO nanoparticles immobilized on scoria rocks

Abstract

ZnO thin film was synthesized by a sol–gel method and dip-coated on granular porous natural scoria. CuO nanoparticles were synthesized on ZnO/scoria using a direct crystallization approach in the presence of sodium borohydride. The structure and characterization of the ZnO/scoria and CuO/ZnO/scoria nanophotocatalysts were studied by X-ray diffraction (XRD) analysis, energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM) and diffuse reflectance spectroscopy (DRS). Photocatalytic decolorization of acid blue 113 and textile wastewater were performed using the CuO/ZnO/scoria nanophotocatalyst under LED visible lamps in a continuous open channel reactor. Effect of pH, flow rate, initial dye concentration and coexisting anions were investigated. A higher acid blue 113 decolorization efficiency was obtained equal to 62.45% at pH = 5, initial dye concentration of 20 mg L⁻¹ and flow rate of 15 ml min⁻¹. For textile wastewater with an initial chemical oxygen demand (COD) of 700 mg L⁻¹, 72% COD removal was obtained at pH = 4 and flow rate of 2 ml min⁻¹.