Preparation of heteropolyacid/TiO2/fly-ash-cenosphere photocatalyst for the degradation of ciprofloxacin from aqueous solutions

Abstract

The TiO2/fly-ash cenosphere photocatalysts modified with heteropolyacid were synthesized by sol–gel followed solvothermal method at 40°C. Their chemical composition and optical absorption were characterized by X-ray diffraction (XRD), UV–vis diffuse reflectance spectra (UV–vis DRS), Fourier Transform Infra Red spectroscopy (FTIR) and Scanning electron microscopy (SEM). It was found that heteropolyacid modification could facilitate the absorption edge of TiO2/fly-ash cenosphere photocatalyst to shift the visible light region. Heteropolyoxanion could be loaded on the titanium dioxide surface, by which could hinder the recombination rate of excited electron holes. The photocatalytic activity of TiO2/fly-ash cenospheres modified with heteropolyacid was observed for the degradation of ciprofloxacin (CPFX) under visible light irradiation. The result from degradation of CPFX suggested that the photocatalytic activity of TiO2/fly-ash cenospheres modified with silicotungstic acid was superior. The synergistic effects of heteropolyacid in modified TiO2/fly-ash cenospheres photocatalyst particles were responsible for improving visible light photocatalytic activity. Besides, the novel photocatalyst was easy to recycle during post treatment because the fly-ash cenosphere was adopted for carrier.