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A green low-temperature deposition and crystallization method was developed to uniformly coat RuO2/TiO2 nanocomposite onto cotton fabrics for efficient solar photocatalysis. The sequential growth of anatase TiO2 and rutile RuO2 on the surface of the cotton was confirmed by XRD, Raman and XPS characterizations. After the deposition of RuO2, the optical properties of RuO2/TiO2/Cotton revealed better visible light absorption and higher charge mobility, and XPS spectra showed that the peaks of Ti 2p3/2 and O 1 s shifted towards the lower binding energies due to the interfacial charge transfer at the robust RuO2/TiO2 mediated with Ti–O–Ru bonding. The photocatalytic performances of the RuO2/TiO2/Cotton were evaluated towards the photodegradation of o-toluidine (o-TD), an aromatic amine widely used in the chemical industry. Compared with TiO2/Cotton, RuO2/TiO2/Cotton exhibited a remarkable improvement in the photocatalytic activity. The presence of RuO2 on the surface of TiO2/Cotton narrowed the band gap and improved the absorption of visible light. Moreover, the successful formation of a robust heterogeneous interface between TiO2 and RuO2 suppressed the charge carrier (e–/h+) recombination effectively. With the RuO2/TiO2 coating chemically bound to the cotton fibers, RuO2/TiO2/Cotton delivered long-term stability in photocatalytic activity and high mechanical durability even after 20 washing times. Our facile and scalable synthesis strategy paved a universal route to efficient immobilization of visible-light-responsible TiO2-based photocatalysts on the low-heat-resistant substrates for various applications. [ABSTRACT FROM AUTHOR]

The photochemical oxidation of styrene under UV-A irradiation in acetonitrile solution containing H 2 O 2 was investigated in absence or in presence of TiO 2 or ZnO. The effects of the molar ratio H 2 O 2 /styrene and of the pH on the disappearance rate and on the selectivity into benzaldehyde and benzene oxide were investigated. Under H202/UV, a conversion of about 6% and a total selectivity into benzaldehyde was observed. In presence of TiO2 the conversion is multiply by 2 and styrene oxide was detected. However, its selectivity is only 10%. At basic pH, in presence of TiO2 or ZnO, the conversion of styrene are 47% and 60% respectively. A similar selectivity of styrene oxide (50%) was found for the both catalysts. However, in presence of TiO 2 benzoic acid is formed with a selectivity of 20% whereas only benzaldehyde was found on ZnO. The impact of the nature of the catalyst and of the active species generated under irradiation were suggested for explaining the difference of reactivity observed. A mechanism of the formation of benzaldehyde and styrene oxide in absence or presence of photocatalyst and of NaOH was proposed. [ABSTRACT FROM AUTHOR]

In this work, the sol-gel technique was carried out to prepare lithium doped ZnO materials with a controlled percentage (3-10 %). The changes in structural, optical and photocatalytic properties were investigated using X-ray powder diffraction, FT-IR spectroscopy, diffuse reflectance UV-visible and scanning/transmission electron microscope. X-ray diffraction showed that ZnO nanoparticles exhibit hexagonal wurtzite structure. The calculated average crystalline size increases from 30 nm of ZnO and 40 nm of ZnO-Li (10 %). The UV peaks positions of the modified samples shifted towards the longer wavelength compared to pure ZnO. The optical band gap of the samples was found to be 3.24 eV for ZnO-Li (3 %) and 3.28 eV for ZnO-Li (10 %), which proves the change in the acceptor level induced by the Li atoms. For the application, the evaluation of the photocatalytic activity is carried out using p-nitrophenol (p-NP) as a model of chemical pollutants. As result, Li doped ZnO materials displayed photocatalytic activity is less than pure ZnO, due to the Li atom that increases the recombination rate of electron-hole pairs, which decreases the photocatalytic activity. [ABSTRACT FROM AUTHOR]

In the present work, the efficiency of UV-A/TiO2 photocatalytic process to remove sulfamethoxazole (SMX) from aqueous solution was investigated using TiO2 Degussa P25 and TiO2 Millennium PC500 immobilized on glass plates. The effects of operating parameters such as initial SMX concentration (10-50 mg L-1), initial pH value (3-9), flow rate of the reactor (0.11-0.48 L min-1) and visible irradiation on process efficiency were studied. All experiments were performed on a fixed-bed recirculating photoreactor. The optimal condition for the SMX removal was obtained at low SMX initial concentration and nearly complete SMX degradation was attained after 7 h irradiation at 10 mg L-1 with TiO2 Degussa P25. The SMX degradation was not affected by the variation of the initial pH of the solution. The effect of flow rate showed that there was no significant impact of this variable on the degradation of SMX, which eliminates the influence of diffusion limitation. Photodegradation seems to follow the Langmuir Hinshelwood pseudo first order kinetic model. The apparent rate constants were found to be 0.008 and 0.003 min-1 under UV irradiation for TiO2 Degussa P25 and TiO2 Millennium PC500, respectively. The obtained results show that supported TiO2 Degussa P25 is more active than supported TiO2500. [ABSTRACT FROM AUTHOR]

Highlights: [•] ZnO-SnO2 photocatalysts were prepared successfully by the coprecipitation method. [•] The best conditions found are: calcination at 600°C/2h; molar ratio Zn/Sn=1/0.05. [•] The lower tin content in the samples led to the higher photocatalytic activity. [•] Zn-Sn0.05 photoactivity under solar light was better than visible lamps light. [ABSTRACT FROM AUTHOR]

Abstract: Supported nanocrystalline titanium dioxide has been prepared by a sol–gel method through the use of mesoporous silica materials SBA-15. The synthesized titania/silica composites were characterized by X-ray diffraction, transmission electron microscopy (TEM) and UV–visible spectroscopy. The TiO2–SBA-15 composites presented in this study showed much higher photodegradation ability of methylene blue (MB) than commercial pure TiO2 nanoparticles Degussa P-25 using different light sources (UV, visible and solar light). Experimental results indicate that the photocatalytic activity of titania/silica mixed materials depends on the adsorption ability of composite and the photocatalytic activity of the titania, and the highest activity was observed on the sample with Ti/Si ratio is about 8. [Copyright &y& Elsevier]

Anionic (Alizarin S (AS), azo-Methyl Red (MR), Congo Red (CR), Orange G (OG)) and cationic (Methylene Blue (MB)) dyes were degraded, either individually or in mixtures, by using UV-irradiated TiO2 in suspension or supported on glass and on paper. The influence of the chemical structure of different dyes as well as that of pH and of the presence of inorganic salts on the photocatalytic properties of TiO2 has been discussed. The role of adsorption is suggested, indicating that the reaction occurs at the TiO2 surface and not in the solution. S and N hetero-atoms are respectively mineralized into SO42−, NO3− and NH4+, except azo-groups which mainly formed N2 which represents an ideal case for a decontamination reaction. The fate of nitrogen strongly depends on its initial oxidation degree.High photocatalytic activities have been found for TiO2 coated on glass by the sol–gel method. Its efficiency was intermediate between those of PC-500 and P-25 powders.The efficiency of PC-500 TiO2 sample, fixed on paper by using a binder, is slightly less important than that of the powder. The presence of a silica-binder with an acidic pzc is suggested to be at the origin of the decrease in efficiency. [Copyright &y& Elsevier]

Paper-TiO 2 -Ag 2 O floating photocatalysts were produced under mild condition and their photocatalytic activity for the degradation of aromatic amine under sunlight stimulant was investigated. Characterizations by Raman, XRD, XPS, DRS and PL confirmed the presence of TiO 2 and Ag 2 O, and the morphology of the appended TiO 2 /Ag 2 O layer was probed by FE-SEM. The photocatalytic activity of the prepared samples was investigated by the degradation of aniline (AN) in water under simulated sun-light illumination and constrained conditions, i.e. non-stirring and non-oxygenation. The presence of Ag 2 O combined with TiO 2 was shown to improve the resistance of paper to bacteria attack, thus increasing the durability of the photocatalyst. Thanks to its hydrophobic character, the paper-TiO 2 -Ag 2 O NPs can be employed as useful floating photocatalyst and can be reused in continuous cycles., (Copyright © 2021 Elsevier Inc. All rights reserved.)