Photocatalytic activity of granular composite TiO2/SiO2 oxides in destruction reactions of dyes

Organic pollutants in the environment undergo decomposition with the help of microorganisms: pollutants are subjected to destruction into simple substances - carbon dioxide, water, etc. Organic pollutants can be divided into natural and synthetic according to their origin. Natural pollutants are of natural origin: metabolic products of living beings, remains of plants, animals, etc. These substances are successfully decomposed by microorganisms living in the environment. Synthetic pollutants are formed as a result of various technological processes or themselves are used in industry. These are phenol and its derivatives, dyes, petrochemical products. These pollutants are synthetic in nature, so the natural microflora is not adapted to them. Decomposition of such compounds proceeds very slowly, sometimes over several decades. As a result, the accumulation of these pollutants occurs, at best, in special landfills, or simply in the environment (soil, lakes, rivers). Existing treatment methods - such as sorption, ion exchange, membrane treatment - do not decompose pollutants, only concentrate them, which leads to their global accumulation. In a number of countries, there are entire lakes and even rivers, rainbow-coloured due to accumulated organic pollution. In the present paper the photocatalytic properties of composite granular photocatalysts have been investigated, in which photocatalytically active nanoscale particles, based on anatase, are embedded in the bulk of a silica gel granule. It has been shown that composite granules successfully oxidize model organic impurities: dyes like methylene blue, methyl orange, and methyl violet.