Degradation of crystal violet over heterogeneous TiO2-based catalysts: The effect of process parameters

Abstract

In this study, modified sol-gel method was employed to synthesize the pure and Zr-doped titania catalysts. Brunauer-Emmett-Teller (BET) method was applied to determine porosity, X-ray diffraction (XRD) analysis was used to study crystal structure, scanning electron microscopy (SEM) was used to investigate morphology and Fourier transform infrared spectroscopy (FTIR) was used to examine surface properties/total acidity of the obtained catalysts samples. Photocatalytic activity was tested in the reaction of crystal violet (CV) dye decolourization/degradation under UV light irradiation. The effects of several photocatalysis operational parameters were considered, such as catalyst dosage, initial dye concentrations, duration of UV irradiation treatment, as well as catalysts calcination temperatures and dopant amounts. The obtained results indicated faster dye decolourization/degradation with the increase of the catalyst dosage and the decrease of initial CV concentrations. The Zr-doping affects photocatalytic properties, i.e. CV decolourization/degradation of the prepared catalytic materials. Thus, addition of 5 wt.% of ZrO 2 to titania increases photocatalytic effect for ∼15% and addition of 10 wt.% of ZrO 2 improves the photocatalytic efficiency of titania for nearly 30%.

Effect of Chelating Agents on the Structural, Optical, and Dye-Degradation Properties of Tungsten Oxide Nanoparticles

“…Degradation time increases with increasing dye concentration. The dye solution at higher concentration hinders the penetration of photons to the catalyst surface, which in turn suppresses the effectiveness of the catalyst in degrading dye molecules [32,33]. The obtained results indicate that the optimal conditions for obtaining better degradation efficiency towards CV dye are 10 ppm dye concentration, 10 mg catalyst dose, and 1 mL H2O2 concentration.…”

“…Degradation time increases with increasing dye concentration. The dye solution at higher concentration hinders the penetration of photons to the catalyst surface, which in turn suppresses the effectiveness of the catalyst in degrading dye molecules [32,33].…”

Decolourization of crystal violet using nano-sized novel fluorite structure Ga2Zr2−xWxO7photocatalyst under visible light irradiation

“…In this manner only, fewer photons can arrive at the catalyst surface, and therefore the creation of HO • free radical on the surface of the catalyst declined, since the available effective sites of catalyst become covered by the crowded dye ions. This results in decolourization rate reduction [68,72,73,76,77,80,81].…”

“…The degradation of 10 mg l −1 CV at optimum reaction time (5 h) and neutral pH were studied at different catalysts loads (0.5-1.25 g l −1 ). Figure 9 displays the direct relation between the % decolourization and the catalyst's loads for both undoped and W-doped GZ catalysts up to 1 g l −1 due to intense numbers of catalytically active sites by increasing of catalysts load [68], that raises the rate of O À † 2 and HO • creation [19]. Reduction of decolourization rate after 1 g l −1 was noted and was owed to the excess catalyst amount impedes the light penetration [20,68,69].…”

“…Figure 9 displays the direct relation between the % decolourization and the catalyst's loads for both undoped and W-doped GZ catalysts up to 1 g l −1 due to intense numbers of catalytically active sites by increasing of catalysts load [68], that raises the rate of O À † 2 and HO • creation [19]. Reduction of decolourization rate after 1 g l −1 was noted and was owed to the excess catalyst amount impedes the light penetration [20,68,69]. Accordingly, 1 g l −1 was elected as the optimum dose for CV degradation.…”