Electrochemical and photocatalytic properties of ZnO nanostructures deposited on nanoporous anodized aluminum oxide membrane and its application for degradation of reactive blue 19 in textile wastewater

Abstract

The current study's objective was to develop a ZnO photocatalyst for the treatment of reactive blue 19 (RB19) from textile wastewater by depositing ZnO nanostructures over nanoporous anodized aluminum oxide (ZnO-AAO). The ZnO-AAO membrane was created using the atomic layer deposition (ALD) technique. SEM, XRD, and EDS morphological and structural characterizations demonstrated that ZnO nanostructures were successfully deposited on the AAO membrane. Studying the optical properties revealed that the band gap energies for ZnO, AAO, and ZnO-AAO membranes were found to be 3.19, 2.85, and 2.92 eV, respectively. This resulted in an improvement in the separation efficiency of photo-excited electrons and holes as well as an increase in the photocatalytic activity of the ZnO-AAO sample in the visible light region. Studying the electrochemical parameters revealed that ZnO-AAO had the lowest charge transfer resistance, which indicates that photoinduced electrons and holes in ZnO-AAO contacts effectively transfer charge and have slower recombination rates. According to research on photocatalytic performance, ZnO-AAO and ZnO photocatalysts required 70 and 90 min of visible light exposure to completely decolorize RB19, respectively. The photocatalytic decolorization of RB19 in an actual sample of textile wastewater showed that the dye could be effectively removed by photocatalytic means when ZnO-AAO membrane photocatalyst was present.