Photocatalytic Degradation of Organic Pollutants

Address:
South Ural State University
76, Prospect Lenina
Office 303, University Building №1A
Tel.: + 7 351 267 95 17
E-mails: avdinvv[at]susu[dot]ru

Research Team

	Viacheslav Avdin D.Sc., Associate Professor
	Igor Krivtsov Ph.D.

The project aims at developing a reagent-free and wasteless method of photocatalytic degradation of organic pollutants resistant to oxidation.

Objectives:

• Optimisation of the existing photocatalytic properties to degrade organic pollutants. The catalyst must interact specifically with the particular pollutant, while other present industrial substances must not disturb the degradation process.
• Studying the kinetics of the photodegradation and the precipitation kinetics of catalyst grains; mathematical modelling of water purification process and catalyst grains extraction; theoretical and experimental research on the optimal grain properties.
• Development of the method for the catalyst surface modification (catalytic activity, pollutant selectivity).
• Design and development of the pilot water purification system (for the MMK plant).
• Development of catalysts tailored for different customers.
• Collaboration with different industrial partners.
• Development of high-tech catalyst manufacturing centres.

About

We developed a method for the synthesis of silica–titania composite oxide using novel solution/sol single precursor containing titanium peroxocomplex and silicic acid. The silica–titania hydrogel is dissolved in hydrogen peroxide. The obtained solution loses its stability as hydrogen peroxide decomposes, and the precipitate is formed. We studied the dried precipitations (xerogel) in comparison with the mixed SiO/TiO xerogel, prepared via the co-precipitation of inorganic salts. The samples prepared via the peroxo method provides a lower degree of molecular homogeneity (i.e., number of Si-O-Ti bonds) than the co-precipitated materials, keeping the anatase phase less prone to rutile formation. Therefore, silicon dioxide does not significantly affect the TiO crystallisation process allowing to achieve higher crystallinity of titanium dioxide. The utilisation of this precursor for the synthesis of the mixed oxides SiO-TiO material in hydrothermal conditions led to unexpected results. We found that in the mixed oxide anastase crystallinity and crystal size increase as the SiO content increases until the equimolar SiO2/ TiO2 state, and then, as the concentration of silicic acid further increases, the crystallinity and crystal size decrease.

The research on photocatalytic properties has shown that this method enables to develop photocatalysts that are five times more effective in their photocatalytic degradation of methylene blue under UV light than its commercially available counterpart.

Results

• Understanding structure formation of composite gels on the basis of silica gel and transition metal oxyhydroxides;
• Development of composite materials on the basis of transition metal oxides;
• Synthesis of silica–titania composite oxide for the application in photocatalysis;
• Development of nanostructured catalysts for resource-efficient technologies.

Future research projects

• The application of the existing nanostructured catalysts for industrial purposes is limited due to the very small aggregate size in the composite (approx. 50 nm) that complicates their extraction from treated water. We have developed a composite catalyst that includes nano-sized particles of titanium dioxide (approx. 10 nm) embedded in the amorphous silica matrix. With that said, the aggregate size grows hundreds of times keeping the same level of efficiency, which allows using these photocatalysts for industrial applications. At present, we are working on the technology of phenol removal from industrial wastewaters that will reduce its emissions and positively affect the environment of the region and, in the future, other Russian regions. We are further planning to commercialise the technology.

Partners