Photocatalytic abatement of VOCs by novel optimized TiO 2 nanoparticles

Abstract

In this work, photocatalytic degradation of different VOCs has been investigated using novel TiO 2 nanoparticles (TNP) at near room temperature. The TNP was synthesized in a vortex reactor by sol–gel process with controlled operating parameters. The final product was optimized through an effective control of the calcination temperatures (400–700 °C) and times (1–7 h). The optimized 10–20 nm particle size TNPs exposed a high specific surface area (151 m 2/g), which was three times higher than the commercial Degussa P 25 TiO 2 material. It also showed rather pure crystalline anatase with small rutile traces, confined band gap energy, relatively more Ti 3+ on the surface, and higher OH surface groups as characterized by X-ray diffraction (XRD), Raman spectroscopy, specific surface area analysis, diffuse reflectance ultraviolet–visible spectroscopy (DR/UV–vis), Fourier transformed-infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The optimized TNP showed superior photocatalytic degradation of ethylene at ambient temperature, as tested in an ad hoc designed Pyrex glass photocatalytic reactor. It was found that the mixed phase of the optimized TNP with a high surface area might induce the adsorption of ethylene and water and generate OH groups which act as oxidizing agents on the TNPs surface, leading to higher photocatalytic activity. The effects of different factors, including adsorption, flow rates, concentrations, catalyst weight and reaction temperature were studied in detail for ethylene, propylene, and toluene oxidation. Moreover, higher photocatalytic activity for VOCs abatement was obtained than the Degussa P 25 TiO 2 due to the above-mentioned characteristics.