APPLICATION OF ACTIVATING INFLUENCES IN OBTAINING TiO2-PILLARED MONTMORILLONITE WITH IMPROVED PHOTOCATALYTIC PROPERTIES

Abstract

A new approach to the obtaining of a highly efficient photocatalyst - TiO2-pillared montmorillonite – by hydrothermally activated intercalation of mechanically dispersed bentonite matrix with the polyhydroxocomplexes of titanium is proposed. The material was characterized by the X-ray diffractometry, low-temperature nitrogen adsorption-desorption, scanning electron microscopy, energy dispersive microanalysis, and zeta potential measurement. The use of short-term (up to 3 min) mechanical dispersion in a planetary mill significantly increases the capacity of cation exchange during intercalation, and the photocatalysts obtained after annealing at 500 °C are characterized by significantly higher values of specific surface area and total pore volume compared with mechanically untreated and initial montmorillonite. The average size of TiO2 crystallites is about 10 nm and the content of anatase is over 90%. Mechanical activation leads to a significant change in the ζ-potential of montmorillonite particles from a significantly negative value in the source material to almost zero, which is an additional argument for more efficient intercalation. Hydrothermal treatment leads to the appearance of coral-like formations of titania on the surface of montmorillonite, and after mechanical treatment they significantly increase in size. Adsorption and photocatalytic properties were studied in a quartz reactor using the rhodamine B dye as example. Complete photocatalytic destruction of the dye was achieved within about 100 min (initial concentration of 40 mg/l, amount of photocatalyst 1 g/l, UV lamp power 250 W). Adsorption kinetics is described by pseudo-first and pseudo-second order models. The kinetics of photocatalysis is described by the Langmuir-Hinshelwood model. The high photoactivity is explained both by the improvement of textural properties and the appearance of additional photocatalytic centers due to the defective structure of mechanically activated montmorillonite. For citation: Ovchinnikov N.L., Vinogradov N.M., Gordina N.E., Butman M.F. Application of activating influences in obtaining TiO2-pillared montmorillonite with improved photocatalytic properties. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2023. V. 66. N 5. P. 59-71. DOI: 10.6060/ivkkt.20236605.6798.