Molecular design of porous nanostructured photocatalysts based on metal oxide nanocomposites for photodestruction of toxic organic substances.

Project Manager: Candidate of technical sciences Yarbekov A.E.

Senior Research Scientist: Ph.D. Mirkhamitova D.Kh.

Researcher: Saidov K.N.

Junior Researcher: Parmanov A.

Senior Research Scientist: Ph.D. Khozhamberdiev M.

Scientific adviser: Ph.D. Ruzimuradov O.N.

Object of study:

Synthesis of nanostructured porous metal oxide composites and their structural, physico-chemical, adsorption and photocatalytic properties.

Method of research work:

sol-gel method in situ, impregnation method – “impregnation”, structural and physicochemical methods of investigation.

Relevance of the topic consists in the fact that as a result of studying the regularities occurring in the formation of a nanostructure in photocatalytic materials, the most optimal conditions for obtaining photocatalytic and sorption materials with qualitatively new properties will be revealed. The structure-properties relationships in catalytic systems based on metal oxides Ti, Sr, etc. have been studied, which is a fundamental problem of modern nanomaterials chemistry and is relevant from the point of view of their promising application in the destruction of various toxic organic substances (phenols, dyes, etc.). .
The purpose of the proposed project is to study the formation of porous photocatalysts based on metal oxide nanocomposites with controlled nanostructures and activity using modern technologies for photodestruction of toxic organic substances (phenols, dyes, etc.). We hope to achieve special preparation of systems in which the organo-inorganic phase and the required interfacial agents are synthesized in one volume using a sol-gel process.

Scientific novelty is determined by the fact that kinetics, formation regularities and process chemistry will be studied, nanostructured photocatalytic and sorption materials based on metal oxide nanocomposites with a given activity in one step using a sol-gel process in situ and an impregnation method are obtained.

Results of work:

A search work was carried out with literature on the synthesis of organic-inorganic nanostructured materials (adsorbents, (photo) catalysts, aerogels, membranes, films, etc.).
A one-stage synthesis of organo-inorganic materials was studied by adding an organic polymer component (templat) to the sol-gel process of inorganic mesh formation during the hydrolytic polycondensation of alkoxymetals. Synthesis of inorganic (SiO2-TiO2) nanocomposites has been carried out and the influence of various factors (type and ratio of initial components, nature and concentration of catalysts, duration of synthesis, temperature, etc.) on the structure and morphology of materials has been studied. The texture and physico-chemical characteristics of the obtained materials are determined by modern analysis methods, such as nitrogen adsorption, IR spectroscopy, X-ray diffraction, microscopic and thermal analyzes. The adsorption and photocatalytic properties of polymer-templated inorganic (SiO2-TiO2) nanocomposites during separation, purification and photodegradation of aqueous solutions of phenols and its derivatives have been studied. A convenient approach for obtaining a macroporous heterostructural TiO2-SrTiO3 monolith by conversion and impregnation of the preformed macroporous TiO2 monolith into an aqueous solution, containing Sr2 + ions, followed by calcination at 800 ° C for 2 hours. The heterostructure TiO2-SrTiO3 was determined, which consists of thin crystals with a size of 15-20 nm and is characterized by a narrow distribution of macropores in size with an average size of ≈ 1.7 μm.

Recommendations for implementation:

Based on the data obtained, recommendations will be made on the use of metal oxide composite nanomaterials as stationary phases for adsorptive separations and as a photocatalyst for oxidation and degradation of toxic organic contaminants in industrial wastewater effluents.

Application area:

the study of methods for the preparation of such metal oxide dispersed materials relates to the latest technologies and will allow solving a number of issues related to the development of special materials for the needs of the chemical industry, modern methods of chemical analysis, medicine, technology for obtaining composite materials, etc. The solution of the set tasks in the project will contribute to the development fundamental, applied and technological research, and the development of scientific foundations will create a number of nanostructured metal oxide dies New generation systems for photodegradation of phenolic compounds, dyes, etc.

Recently, the problem of developing scientific foundations for the production of organic-inorganic nanomaterials of the new generation is relevant for solving a number of problems in medicine, the chemical industry, biotechnology, sensitive methods for monitoring and analyzing environmental objects and residual amounts of pollutants. These issues can be solved with the help of new technologies for the synthesis of highly effective sorption materials, which have different functional groups in their composition. Methods for the introduction of functional groups are associated with immobilization, sol-gel process and chemical grafting on the surface of solid materials. Promising is a one-stage way of synthesizing inorganic adsorbents, photocatalysts, films, etc. using a sol-gel process. These materials, obtained by the sol-gel method, belong to the class of nanocomposite materials, the science of which arose in recent years at the junction of various fields of knowledge about polymers, colloid chemistry, and physicochemistry of ultradisperse systems. A characteristic feature of such materials is the nanometer size of their structural elements, as well as the distances between the meshes and layers formed by polymeric organic and inorganic ingredients. As a rule, they exhibit synergism of the properties of the original components and possess unique properties, which allows them to be used in materials science and causes application in practice. Nanostructured metal oxide composite materials are promising for the production (photo) of catalysts, gas separation membranes, adsorbents for high-performance liquid chromatography. Continuous growth and development of chemical, pulp and paper, petrochemical, chemical and pharmaceutical industries leads to a constant increase in environmental pollution by hazardous organic compounds. One of the highest ecological loads is experienced by water resources, with an increasing number of highly toxic compounds entering the water basins of the water basins used by man for domestic and household needs. Therefore, one of the primary tasks of modern science is to solve the problem of water resources contamination with highly toxic organic compounds, which requires detailed physical and chemical studies. Phenol and its derivatives are the most dangerous pollutants of water resources. Thus, the minimum toxic doses, which reduce by 50% the number of microorganisms that render harmless compounds in water safe, are only 22.1 mg / l, 0.08 mg / l, 31.8 mg / l, respectively, for phenol, hydroquinone and catechin. Thus, the entry of even a small amount of phenolic compounds into the reservoir leads to a decrease in the ability of the water body to regenerate itself with the help of the available geobiocenosis and the impossibility of further deactivation of other contaminants. In addition, phenol and its derivatives are highly toxic to humans and belong to highly dangerous substances of the 2nd hazard class, and the phenol content in drinking water should not exceed the MPC = 0.001 mg / l. For the removal of phenolic compounds currently used: extraction, sorption, membrane and biological purification methods, but none of the above methods allows for effective removal of phenol, which is due to insufficient purification, a large number of by-products, high energy intensity and, as a consequence , a significant cost of cleaning. All of the above requires the creation and implementation of new highly efficient wastewater treatment technologies from phenolic compounds. The use of modern adsorption-catalytic systems allows achieving a deep conversion of phenolic compounds down to carbon dioxide and water in high yield. Special attention should be paid to the possibility of using nanoparticles of transition metals, which makes it possible to significantly change the direction and speed of chemical processes. The versatility of the properties of cluster and nanoscale particles synthesized in the last decade makes it possible to use them in
process of deep oxidation of phenolic compounds. However, the successful use of such systems is possible only if they are systematically studied, including a physico-chemical analysis of the formation, morphology, structure, and state of nanoparticles, the sorption of substrates and reaction products on the surface of synthesized
nanoparticles, the study of the kinetics and mechanism of the reaction. Physico-chemical research and analysis of nanostructured systems makes it possible to conduct their directed synthesis with predetermined properties. The synthesized photocatalytic system should provide a high rate of oxidation of phenolic pollutants, effective oxidation of a wide
spectrum compounds with different functional groups, have a low cost and long life without significant loss of catalytic properties, and also have high mechanical strength and be immune to catalytic poisons. Application of nanotech