Search

New NT:M/zeolite composites with functional nanoparticles of titanium(IV) oxides NT (η-phase and anatase) have been prepared by introducing nitrates with dopant metals (M = Ag, Ni, and V) and zeolites (H-Beta and H-ZSM-5) within the process of NT synthesis during the hydrolysis of TiOSO4·nH2O. The prepared composites have been characterized by X-ray diffraction, XAS-method, XPS-spectroscopy, UV-Vis diffuse reflectance spectroscopy, and Brunauer–Emmett–Teller and chemoluminescence methods. The greatest photodegradation rate constants (visible light radiation) were achieved in the reaction of thiamethoxam pesticide and difenoconazole fungicide oxidation in the presence of NE:Ni/H-Beta (NE – η-phase with composition TiO2−x·nH2O), i.e. k = 0.0270 min−1 and k = 0.0147 min−1 respectively, that is 2.5 times higher than the k value obtained for the commercial anatase Hombifine N (UV-irradiation). A relationship between the photocatalytic activity (PCA) and the NT:zeolite ratio, the type and concentration of M, the type of NT and zeolite, the content of OH groups and the reactive oxygen species (radical anions ˙OH, ˙O2− and H2O2) on the surface, and the composition and structure of the decomposed pollutant has been found. The decisive role of the composition of the volume and surface of nanocomposites in the realization of PCA has been noted. The adsorption (removal of P(V), As(V), Se(VI) ions from aqueous solutions) and antimicrobial activities (against bacteria Staphylococcus epidermidis, Bacillus antracoides, Escherichia coli) of the NT:M/zeolite composites, in the absence of light emission, have been studied for the first time and their high performance has been demonstrated: the removal degrees of P(V), As(V), and Se(VI) ions from aqueous solutions in the presence of all composites were more than 99% and the inhibition growth zone of composites NA:Ag/zeolite was >13 mm. New composites could be recommended for preparing wound dressings, antiseptic ointments for external use and water filters.

Samples containing vanadium-doped nanosized titanium(IV) oxides with anatase and η-phase structures were prepared by a modified sulfate process, and samples with vanadium-doped η-phase were prepared for the first time. The bulk and the surface of the samples were characterized by a lot of methods, including X-ray diffraction, diffuse reflectance spectroscopy, X-ray absorption spectroscopy (EXAFS/XANES), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The photocatalytic activity (PCA) of the samples was studied in the reaction of photodegradation of the cationic dye rhodamine 6G (in the visible region) and the systemic triazole fungicide difenoconazole (in the UV and visible regions). The PCA was found to be influenced by the phase composition of the samples, the composition of their surface, and nanosized titanium(IV) oxide modifications. Vanadium-doped samples with η-phase containing different ions (Ti3+, Ti4+, V4+, and V5+) and reactive OH groups on the nanoparticle surface exhibited the highest PCA. The samples were shown to have a higher adsorption capacity (AC) for the extraction of As(V) (the highest AC in the presence of vanadium-doped anatase and η-phase) and P(V) (the highest AC in the presence of undoped anatase and η-phase) anions from aqueous systems. The adsorption capacity correlates with the amount of reactive OH groups on the nanoparticle surface and does not depend on the modification of the adsorbent. Only vanadium-doped anatase containing the largest fraction of an amorphous component and the largest amount of SO42− groups on its nanoparticle surface exhibits antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Bacillus anthracoides. Vanadium doped anatase and η-phase can be used to purify aquatic environments of harmful organic pollutants and a wide range of anions.

This study produced for the first time composites based on polystyrene microspheres with nano-sized titania synthesized by sulfate and sol-gel methods, as well as commercial Hombifine N, Hombikat UV100, and Degussa P25. The starting samples and the composites were characterized by X-ray diffraction, scanning electron microscopy, nitrogen adsorption capacity, and IR spectroscopy. The highest content of nano-titanium dioxide both in the bulk and on the surface of microspheres was obtained with the use of Hombikat UV100. This sample has the largest specific surface area and a high content of reactive OH groups. The adsorption properties of composites were investigated.