Pure and Fe-Doped Mesoporous Titania Catalyse the Oxidation of Acid Orange 7 by H2O2 under Different Illumination Conditions: Fe Doping Improves Photocatalytic Activity under Simulated Solar Light

Abstract

A sample of mesoporous TiO 2 (MT, specific surface area = 150 m 2 ·g −1 ) and two samples of MT containing 2.5 wt.% Fe were prepared by either direct synthesis doping (Fe2.5-MTd) or impregnation (Fe2.5-MTi). Commercial TiO 2 (Degussa P25, specific surface area = 56 m 2 ·g −1 ) was used both as a benchmark and as a support for impregnation with either 0.8 or 2.5 wt.% Fe (Fe0.80-IT and Fe2.5-IT). The powders were characterized by X-ray diffraction, N 2 isotherms at −196 • C, Energy Dispersive X-ray (EDX) Spectroscopy, X-ray Photoelectron Spectroscopy (XPS), Diffuse Reflectance (DR) ultra-violet (UV)-Vis and Mössbauer spectroscopies. Degradation of Acid Orange 7 (AO7) by H 2 O 2 was the test reaction: effects of dark-conditions versus both UV and simulated solar light irradiation were considered. In dark conditions, AO7 conversion was higher with MT than with Degussa P25, whereas Fe-containing samples were active in a (slow) Fenton-like reaction. Under UV light, MT was as active as Degussa P25, and Fe doping enhanced the photocatalytic activity of Fe2.5-MTd; Fe-impregnated samples were also active, likely due to the occurrence of a photo-Fenton process. Interestingly, the Fe2.5-MTd sample showed the best performance under solar light, confirming the positive effect of Fe doping by direct synthesis with respect to impregnation.

Nanomaterials for the Abatement of Pharmaceuticals and Personal Care Products from Wastewater

“…When Degussa P25 was adopted as a photocatalyst, the drug adsorption at the surface of TiO2 NPs played an important role, in that the drug adsorption was enhanced at alkaline pH, whereas mass transfer problems occur at acidic pH (where both the drug and the TiO2 surface are protonated). A similar result was observed by some of us when the adsorption of negatively charged species on mesoporous TiO2 were studied [49,50].…”

Effects of the Brookite Phase on the Properties of Different Nanostructured TiO2 Phases Photocatalytically Active Towards the Degradation of N‐Phenylurea

“…6a), the band at 235 nm markedly decreases with all the samples: −NH 2 substituted benzene rings usually absorb close to 230 nm and, thus, disappearance of the 235 nm band may indicate some degradation processes concerning the —NHCONH 2 group. Simultaneously, a new band is seen to appear at 213 nm, likely due to formation of some hydroxylated compounds, as expected during photodegradation in water, implying the occurrence of ⋅OH radicals, which are strong oxidizing species able to attack benzene rings (phenol absorbs at 210 nm) . Unfortunately, the adopted UV/Vis spectroscopy technique does not allow gaining further insights into the degradation mechanism, which is, by the way, out of the scope of this paper.…”

Recent Progress in the Abatement of Hazardous Pollutants Using Photocatalytic TiO2-Based Building Materials

“…TiO 2 -inclusive photocatalytic materials were developed to degrade indoor VOC pollutants under UV light irradiation [140,141]. Several TiO 2 -based photocatalytic materials have been developed for the decomposition of VOCs [142][143][144][145]. These reviews, published in the years between 2014 and 2019, focus the discussion on the utility of TiO 2 -based photocatalytic building materials towards VOC abatements.…”