A Comparative Study of the Activity of TiO2 Degussa P25 and Millennium PCs in the Photocatalytic Degradation of Bromothymol Blue

Abstract

The photocatalytic activities of TiO2 Degussa P25 and Millennium PCs (PC50, PC100, PC105 and PC500) were evaluated by the photocatalytic degradation of Bromothymol Blue (BTB). The relationship between the photocatalytic reaction and the adsorption of BTB on the TiO2 catalysts at acidic, natural and basic mediums of pH was investigated. The crystalline phase, average crystalline size and surface area of the catalyst were found to have a significant influence on the adsorption and photocatalytic activity of the TiO2 samples. The mixed phase of anatase/rutile (Degussa P25) was found to be the most efficient photocatalytical material than pure phase anatase (Millennium PCs) and faster degradation is observed for PC500 compared to other Millennium PCs, this was attributed to the high surface area of PC500. Within the PC50, PC100 and PC105 series, the photocatalytic efficiency increased with the decrease of the surface area. The COD and TOC removals increased slowly, however, the decolorization ratio of BTB increased rapidly at the same time. Thereafter, the efficiency of P25 and PC500 were compared in presence of H2O2, Cl− and HCO3− at different mediums of pH. H2O2 was found to enhance strongly the BTB degradation in presence of P25 with an optimum at natural pH. In contrast, the reaction was inhibited in the presence of PC500, due to the inhibition of dye adsorption. At different pH, the BTB degradation has been significantly inhibited in the presence of the mixtures of HCO3−/H2O2. In contrast, the mixtures of Cl−/H2O2 accelerate the BTB degradation at acidic pH.

Optimization of TiO2-P25 photocatalyst dose and H2O2 concentration for advanced photo-oxidation using smartphone-based colorimetry

“…This small surface area suggests rather low adsorption properties. This is consistent with the study (Bouanimba et al 2018) which showed that the P25 photocatalyst is not able to adsorb the dye Bromothymol Blue and it provides much faster photodegradation compared to other TiO 2 samples. Moreover, previous studies have shown that the P25 photocatalyst provides rapid degradation of many organic compounds (Katal et al 2020).…”

Synthesis and Characterization of Titanium Dioxide Hollow Nanofiber for Photocatalytic Degradation of Methylene Blue Dye

“…Degussa P25, a commercially available TiO 2 , is one of the most efficient photocatalysts in terms of cost and photocatalytic ability, with a number of works published elsewhere [ 7 , 8 , 9 , 10 , 11 ]. Despite that, these studies reported some issues with this particular photocatalyst, and one of them is the high bandgap energy (~3.2 eV) The high bandgap value limits the light utilization efficiency and reduces the number of electrons that could participate in the redox reaction, which consequently deteriorates the photocatalytic activity.…”

Synthesis of ZnO Nanostructures Using Sublimation-Condensation and Sol-Gel Methods: Evaluation of the Photocatalytic Degradation Activity of Industrial Dye

“…The XRD spectra of the obtained nanoparticles are shown in Fig. 2 Crystallite size was obtained by Debye-Scherrer formula given by equation [16,20]:…”

“…In addition, another reason can explain these results is that after the addition of HCO − 3 ions, CO •− 3 radicals has been formed in the solution, since carbonate radicals can attack the dye molecules and enhance the photocatalytic reaction, however, the CO •− 3 radicals are less reactive than • OH radicals [16].…”

“…Synthetic dyes constitute one of the larger groups of pollutants in wastewater released from textile, leather tanning, paper production, plastics, and other industries. These dyes have a big impact on the environment because of their potential carcinogenic properties [15,16].…”