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Al-doped TiO2 nanoparticles with different Al contents were prepared by a simple sol–gel method and were applied as UV filters for sunscreen products. These materials were characterized by XRD, Raman, FESEM, N2 adsorption-desorption, WDXRF, FTIR, and UV–visible diffuse reflectance spectroscopy. Their color and photocatalytic activity were evaluated through CIE L*a*b* colorimetric method and the degradation of methylene blue under UV light, respectively. According to the results, the insertion of Al3+ ions into TiO2 successfully reduced the photocatalytic performance via the decrease in the mass fraction of rutile phase, the decrease in surface hydroxyl groups, and the increase in dislocation density. These Al-doped powders display better UV absorption than the undoped TiO2, which can be attributed to the increase in anatase content and the decrease in particle size due to Al-doping. Consequently, the sunscreen using 4 mol% Al-doped TiO2 reveals the enhanced SPF value and improved color stability, which are suitable for UV protection cosmetics. Highlights: Preparation of Al-doped TiO2 nanoparticles by sol-gel method. Al-doping successfully reduces the photocatalytic activity of TiO2. Al-doped TiO2 nanoparticles show high UV absorption and bright ivory-white color. Sunscreen using Al-doped TiO2 display high SPF values and high color stability. Al-doped TiO2 nanoparticles can be safety used as UV filters in sunscreens. [ABSTRACT FROM AUTHOR]

The present paper reports the synthesis of magnetic photo-Fenton catalysts based on CuFe2O4 via an environmentally friendly sol-gel method at different annealing temperatures (700, 800, and 900°C) using tamarind fruit extract as a chelating agent. The catalysts were characterized by X-ray diffraction, scanning electron microscopy, nitrogen adsorption, Fourier-transform infrared spectroscopy, and vibrating sample magnetometry. Their photo-Fenton catalytic performance was tested with oxalic acid for the degradation of Methylene Blue under UVA light and under visible light. According to the results, the annealing temperature was found to be the important factor, significantly affecting the oxalic acid-induced-photo-Fenton activity. When the annealing temperature increased from 700 to 800°C, the catalytic performance was strongly improved, which can be explained by the enhanced Fe3+ content on the catalyst surface. At higher annealing temperature, due to the growth and agglomeration of particles, the specific surface area was decreased, consequently reducing the catalytic activity. The sample prepared at 800°C also displayed good ferromagnetic properties, making it the most promising recyclable material for wastewater treatment in this study. [ABSTRACT FROM AUTHOR]

An Erratum to this paper has been published: https://doi.org/10.3103/S1063455X24030123 [ABSTRACT FROM AUTHOR]

The aim of the study was to prepare magnetic photo-Fenton catalysts based on CoFe2O4 by polyethylene glycol-assisted sol-gel method for the degradation of methylene blue under UVA and visible light irradiation with H2C2O4 as a radical producing source. The catalysts were synthesized at different annealing temperatures in order to investigate the influence of annealing temperature on their crystal structure, morphology, surface functional groups, magnetic properties, and their photo-Fenton catalytic activity. According to the results, when the annealing temperature increased from 600 to 800 °C, the content of CoFe2O4 cubic spinel phase was significantly enhanced, the amount of Fe3+ ions in the tetrahedral sites also increased on the surface of samples, which improved the magnetic properties as well as the photo-Fenton catalytic performance under both UVA and visible light. However, at the annealing temperature of 900 °C, the photo-Fenton activity was declined, which can be attributed to the growth of catalytic particles and the decrease of Fe3+ ions on their surface. Preparation of CoFe2O4 catalysts by polyethylene glycol-assisted sol-gel method.Increasing of annealing temperature improves the CoFe2O4 phase content.The Fe3+ ions in surface tetrahedral sites increases with annealing temperature.Enhanced CoFe2O4 phase and surface Fe3+ contents improve the photo-Fenton activity.H2C2O4 plays as an efficient radical source for the photo-Fenton catalysis. [ABSTRACT FROM AUTHOR]

Abstract: Magnetic Mn2O3/CuFe2O4 catalysts for the synthesis of p-hydroxybenzaldehyde were prepared by a facile in-situ growth method at different annealing temperatures in order to study the influences of annealing temperatures on their structure, atomic composition, morphology, surface functional groups, magnetic and catalytic properties. The catalytic performance was evaluated via the aerobic oxidation of p-hydroxybenzyl alcohol to p-hydroxybenzaldehyde. All Mn2O3/CuFe2O4 catalysts exhibited the activity for the synthesis of p-hydroxybenzaldehyde with the selectivity of 100% and ferromagnetic properties, which allows them to be easily separated from the solution by a magnet. When the annealing temperature increased from 300 to 500 °C, the atomic manganese content on the surface and the particle size were not modified, but highly crystalline α-Mn2O3 was formed on the surface of CuFe2O4 nanoparticles, leading to the enhanced conversion of p-hydroxybenzyl alcohol. It was also observed that the elemental composition and the core–shell structure of this catalyst remained unchanged after the synthesis of p-hydroxybenzaldehyde, which ensures its magnetic separation. However, when the annealing temperature rose up to 700 °C, the catalytic activity was reduced, due to the increase of Mn–O bonding strength and the growth of particles.Graphical Abstract: [ABSTRACT FROM AUTHOR]