Synthesis and characterization of CuAl2O4 nanoparticles: Application for the removal of Eriochrome Black T under solar light irradiation

Abstract

This work focuses on the use of the spinel CuAl2O4 as photocatalyst for the degradation of Eriochrome Black T (EBT), a potentially hazardous dye. CuAl2O4 is synthetized by co-precipitation and studied by physic-chemical and electrochemical properties. X-ray diffraction revealed the formation of a single phase with cubic symmetry with a homogeneous morphology. X-ray Photoelectron Spectroscopy (XPS) and FTIR spectroscopy provide a better understanding of the chemical composition and surface structure of CuAl2O4. Diffuse reflectance (DR) gave a band gap of 1.94 eV, attributed to Al3+ in octahedral configuration. The BET analysis led to a specific surface area of 37 m2/g with the availability of an appreciable surface for photochemical reactions. Chrono-amperometry indicated n-type conductivity of CuAl2O4, with electrons as dominant charges and an activation energy (Ea) of 0.17 eV. A flat band potential of 0.26 VSCE (Volt vs. Saturated Calomel Electrode) was calculated from the interfacial capacitance in Na2SO4 solution. The photoactivity of EBT degradation was assessed by using chemical oxygen demand (COD). A quasi-complete degradation of EBT was observed within 180 min under sunlight. The mineralization was carried out with an initial EBT concentration of 10 mg/L, a dose of 1 g/L at pH ∼ 8, similar to that of an aquatic environment. These experimental conditions are important to assess the applicability of this method in a real environment.