Abstract
In this work, the influence of simple acids in the room temperature sol-gel synthesis of TiO2 was investigated and the efficiency of prepared photocatalysts was evaluated in the removal of caffeine. To improve the photoactivity of TiO2, vanadium-doped TiO2 (VTiO2) samples were obtained starting from different amount of vanadyl sulphate as a dopant source. The samples were centrifuged, washed and finally dried at room temperature, and no calcination step was carried out. The prepared photocatalysts were characterized by different techniques (X-ray powder diffraction (XRD), specific surface area (SSA), ultraviolet-visible diffuse reflectance spectra (UV-vis DRS) and Raman). VTiO2 photocatalysts were tested in the photocatalytic removal of aqueous solutions containing caffeine. The photocatalytic tests were carried out in a recirculating batch cylindrical photoreactor irradiated by a UV LEDs strip (nominal power of 12 W and wavelength emission peak at about 365 nm) surrounding the external surface of the reactor. The optimized VTiO2 photocatalyst was able to reach a caffeine degradation of about 96% after 360 min of UV light irradiation with a total organic carbon (TOC) removal of 72%.
Highlights
The design of nanomaterials is a critical issue for industrial applications and their preparation methods largely affect the efficacy of nanotechnology and their application
TiO2 based photocatalysts were obtained at room temperature starting from a modified sol-gel method
The characterization data showed that the presence of nitric acid during the synthesis induced the formation of a biphase crystalline structure TiO2
Summary
The design of nanomaterials is a critical issue for industrial applications and their preparation methods largely affect the efficacy of nanotechnology and their application. TiO2 is used in a wide range of common and high-tech applications due to its moderate price, chemical stability, non-toxicity, biocompatibility and efficient photocatalytic properties [1]. It was reported that the photocatalytic activity of TiO2 depends on crystal size, specific surface area, crystallinity and absorption properties [2]. Among the various crystalline phases of titania, anatase shows a better photocatalytic activity [3]. It is well known that anatase TiO2 , with a small fraction of rutile or brookite phase, showed enhanced photocatalytic activity compared to pure anatase TiO2 due to the improved electron and hole separation [4]. Some papers report that anatase-brookite composites were more efficient than anatase-rutile TiO2 for the photodegradation of a wide range of organic pollutants [5]
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