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In this paper, we analyze the structural, morphological, and magnetic properties of CaMn 1−x Mo x O 3 (x = 0.08, 0.10, 0.12) system prepared by the usual solid-state reaction method. The results obtained by scanning electron microscopy (SEM) show an appropriate sintering process, and energy dispersive spectroscopy (EDS) shows that there is not a presence of strange elements. The X-ray diffraction analysis (XRD), through the Rietveld method, reveals that samples crystallize in a Pnma (62) orthorhombic structure, with an increase in the unit cell volume as a function of Mo concentration. Curves of magnetization zero field cooling (ZFC)-field cooling (FC) in a temperature range of 50 to 350 K show similar paramagnetic behavior of every applied field above 110 K in each one of the Mo doping. Below this temperature, the magnetic response becomes ferromagnetic. The antiferromagnetic transition was analyzed by fitting of the Curie-Weiss law. An increase in total effective magnetic moment and Neel temperature, ranging from 200 to 295 K, is observed when Mo concentration increases in CaMn 1−x Mo x O 3 (x = 0.08, 0.10, 0.12) system.

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The extensive production of coal fly ash by coal combustion is an issue of concern due to its environmental impact. TiO2-zeolite composites were synthesized, at low cost, using recycled coal fly ash from a local thermoelectric power plant to produce the zeolite using the hydrothermal method. TiO2 was loaded by means of the impregnation method using ethanol and titanium isopropoxide between 8.7 and 49.45 wt% TiO2. The samples were characterized by X-ray diffraction, Raman, electron spin resonance, high-resolution transmission electron microscopy, N2 adsorption-desorption, doppler broadening of annihilation radiation, and diffuse reflectance techniques, and the photocatalytic activity of the composites was evaluated according to the degradation of methyl orange under UV light. The results show that TiO2 crystallizes in the anatase phase with a Ti3+ oxidation state, without post-treatment. TiO2 particles were located within the pores of the substrate and on its surface, increasing the surface area of the composites in comparison with that of the substrates. Samples with TiO2 at 8.7 and 25 wt% immobilized on hydroxysodalite show the highest degradation of methyl orange among all studied materials, including the commercial TiO2 Degussa P25 under UV light.

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In order to improve the photocatalytic effect of Nb2O5, manganese from 1% to 10% was added by the polymeric precursor’s method. The samples obtained were subjected to different calcination temperatures from 400 to 700 °C. Characterization of the synthesized materials was performed by XRD, IR, Raman and Diffuse Reflectance Spectroscopy (DRS) spectroscopy, FE-SEM, Brunauer–Emmett–Teller (BET) method, Photoluminescence (PL) and Dynamic Light Scattering (DLS). Photocatalytic performance for degradation of Rhodamine B was also evaluated. The Rietveld refined X-Ray Diffraction (XRD) pattern of Nb2O5:Mn 1.0 wt.% (700 °C) sample was similar to that of the un-doped oxide, therefore indicating that Nb was replaced by Mn and, consequently, there are not significant variations in the oxide structure. The Nb2O5:Mn 10.0 wt.% (700 °C) sample has the lowest band gap energy. The specific surface area (SBET) PL value increased as manganese concentration increased. The Nb2O5:Mn 5.0 wt.% (700 °C) sample has an Eg of 3.15 eV and morphological and surface characteristics that made it an appropriate photocatalyst in the Rhodamine B degradation. The novelty of this work relies on the use of a small quantity of Mn ions as dopants leading to Nb2O5:Mn nanostructured particles without using any surfactant or other additives.