Influence of gamma-irradiation on the photocatalytic activity of Degussa P25 TiO2

Abstract

The purpose of this article is to study the influence of gamma irradiation on the sorption capacity and photocatalytic activity of commercially available TiO 2 Degussa P25. The photocatalyst was gamma-irradiated at ambient temperature with doses 8-60 kGy ( 137 Cs, dose rate 2 kGy/24 h) and then stored until analysis/tests in liquid N 2 . X-ray diffraction, SEM, TEM, EPR, and UV-VIS reflectance spectrometry were applied to explore phase composition, crystal cell parameters, crystallite size, textural properties (grain size, and specific surface area), the presence of paramagnetic centers, and UV/VIS absorption of the initial and irradiated samples. The sorption capacity and photocatalytic activity of the products under UVA (17 W, k max = 365 nm) and sunlight irradiation were studied against Malachite Green 10 -5 M aqueous solution, applied as a model pollutant. The sorption capacity varied non-monotonically with the irradiation dose, with clearly expressed maximum and minimum seen at irradiation with doses of 28 and 60 kGy, respectively. The maximum in the photocatalytic activity, both at UV and sunlight illumination, is observed after the dose of 28 kGy is applied; at these conditions, the pollutant degradation rate constant is 1.7/2.7-times higher than the value for the non-irradiated product. The explanation of the obtained results is related mainly to the type and concentration of gamma-generated defects in catalysts, and especially the effect of Ti 3? is discussed. Some of the considered factors may act in opposite directions, causing an extreme point in the relation between the photocatalytic activity and the gamma radiation dose.

Effect of gamma radiation on the photocatalytic properties of Cu doped titania nanoparticles

“…In this context, some results, obtained by the application of gamma irradiation treatments on P25 (Degussa) TiO 2 photocatalyst commercial products, showed a surface effect with no significant change on morphology and crystal structure. Optical property investigations revealed an extension of the light absorption from UV down to the visible region, leading to an improvement of the photo-response [18,19]. These findings have been assigned to trapped electrons in oxygen vacant sites or to Ti 3+ states formed in the few atomic layers at the surfaces of TiO 2 crystallites.…”

“…Recently, reduction methods (e.g., by high-energy particle bombardment) showed interesting results in producing catalysts with great photocatalytic performance [17][18][19]. Those methods lead to generate disordered TiO 2 nanophases with simultaneously incorporated oxygen vacancies self-dopants over a few atomic layers at the surface of TiO 2 nanocrystals.…”

Characteristics and Behavior of Different Catalysts Used for Water Decontamination in Photooxidation and Ozonation Processes

“…DTZ degradation by UV/AC and solar/AC systems was also compared with that obtained by the conventional utilization of TiO2 as a photocatalyst. Results in Figure 3 show higher DTZ degradation with solar/TiO2 than with solar/AC systems, attributable to the major difference between the illumination intensity created by solar radiation (64.52 W/m 2 ) and that created by the UV radiation photoreactor (34.62 W/m 2 ) [86]. However, the degradation rates obtained by UV/AC systems are much higher than those obtained by UV/TiO2 system.…”

Visible Light-Driven Photocatalytic Activity of Magnetic Recoverable Ternary ZnFe2O4/rGO/g-C3N4 Nanocomposites

“…The equipment and the procedure applied were similar with those used in our previous studies. [14][15][16][17][18]35,36 For illumination 15W white LED (manufactured by V-TAC), 418-700 nm, situated at 10 cm distance abоve the slurry was used.…”

“…Photocatalytic processes have also been applied, and much effort has been spent on the development of different semiconductors as photocatalysts among which TiO 2 and its modifications is well known. [13][14][15][16][17][18] The aim of the research presented here is to develop new photocatalysts and to overcome the main limitation of TiO 2 , i.e. its wide band gap (3.2 eV) that makes it active under UV light irradiation only (about 5% of sunlight).…”