Investigation of the effect of heat treatment process on characteristics and photocatalytic activity of TiO2-UV100 nanoparticles

The effect of heat treatment process on crystallite size, phase content, surface area, band gap energy and photocatalytic activity of TiO 2-UV100 nanoparticles were investigated. Heat treated TiO2 nanoparticles were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) isotherm and diffuse reflectance spectroscopy (DRS) techniques, and its photocatalytic activity was investigated in the removal of C.I. Acid Red 88 (AR88), an anionic monoazo dye of acid class, as a model contaminant. Heat treatment process at 600 °C causes an increase in crystallite size and band gap energy of TiO2-UV100 nanoparticles. The results indicate that the nanoparticles treated for 1 h at 600 °C show the highest photocatalytic activity which can effectively degrade AR88 under UV-irradiation. Increasing heat treatment temperature above 600 °C led to reduction in TiO2 photoactivity which may be related to the anatase-rutile phase transformation, increasing particle size and decreasing specific surface area. Removal efficiency of AR88 with heat treated TiO 2-UV100 nanoparticles was sensitive to the operational parameters such as catalyst dosage, pollutant concentration and light intensity

Decolourization of tartrazine from aqueous solutions by coupling electrocoagulation with ZnO photocatalyst

Decolourization of tartrazine (C.I. Acid Yellow 23, AY23) in aqueous solutions has been investigated by coupling electrocoagulation and ZnO photocatalyst methods and also by a comparison between ZnO, UV, EC, UV/ZnO, UV/EC, and EC/UV/ZnO systems in the removal of AY23 as a model contaminant. Results indicated that the decolourization efficiency was in order of EC/UV/ZnO > UV/EC > EC > UV/ZnO > ZnO > UV. Combining EC with UV/ZnO can trigger the Fenton or Fenton-like reaction, which accelerates the rate of decolourization. Desired operating conditions for decolourization of 40 mg·dm-3 AY23 solution in EC/UV/ZnO process were [ZnO] 0=650 mg·dm-3, [NaCl] = 800 mg·dm-3, light intensity = 31/2 W·m-2, current density = 120 A·m-2, electrodes distance = 15 mm, pH = 6.29, stirring rate = 900 rpm and electrodes of steel 304/A1, which yielded 99.70% colour removal in 5 min of treatment time