Investigation of enhanced degradation of the antibiotic under visible in novel B/ZnO/TiO2 nanocomposite and its electrical energy consumption

Abstract

Both ZnO and TiO2 are common semiconducting metal oxides with high mechanical and chemical durability. However, they only have good photocatalytic ability in the UV region, besides the rapid recombination between electrons and holes reduces the efficiency of the decomposition of organic substances. To improve their catalytic efficiency, in this study, ZnO and TiO2 were doped with B to produce the novel B/ZnO/TiO2 nanocomposites for degrading tetracycline hydrochloride (TCH) in the aqueous solution. The characteristics of samples were analyzed by the diffuse reflectance ultraviolet–visible (DR/UV–vis), scanning electron microscope (SEM), energy-dispersive (EDS), Fourier transform infrared spectroscopy (FT-IR), and x-ray diffraction (XRD) techniques. The 3B/ZnO/TiO2 sample had a band gap energy (E g) of 3.21 eV. Although the B/ZnO/TiO2 sample had a tightly aggregated morphology composed of many nanoparticles in 33–137 nm, it still exhibited a higher uniformly and photocatalytic efficiency than ZnO and ZnO/TiO2. At the optimal doped B of 3 wt%, the degradation efficiency (DE) was achieved at 96.33% with a rate constant of 0.067 min−1. The factors that affect the photocatalytic process such as the initial TCH concentration, the catalyst content, and the pH solution were comprehensively investigated. In addition, the stability of 3B/ZnO/TiO2 nanocomposite was evaluated via three consecutive cycles and the DE was 69.75% in 3rd cycle. The Z-scheme mechanism was proposed for the photocatalytic mechanism of TCH in the B/ZnO/TiO2 catalyst. In addition, electrical energy consumption was estimated that the electrical energy per order only was 29.05 kW.h.l−1.