New composites based on zeolites (H-Beta, H-ZSM-5) and nanosized titanium(iv) oxide (anatase and η-phase) doped by Ni, Ag, V with photocatalytic, adsorption and bactericidal properties

Abstract

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 TiO_2−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.