Photocatalytic (Reagent-free) Water Treatment by Removal of Persistent Organic Pollutants

Team Head, Dean of the SUSU Faculty of Chemistry Vyacheslav Avdin Doctor of Sciences (Chemistry), Associate Professor avdinvv[at]susu[dot]ru

Project goal is to develop and introduce a new reagent-free and waste-free method of photocatalytic destruction of oxidation-resistant organic pollutants in water medium.

Problems:

1. The most hazardous for the environment are synthetic organic substances because natural microflora is not adapted to them. They are called persistent organic pollutants (POPs). POPs include herbicides and pesticides, cyanides, phenol derivatives, petroleum products, etc. All these substances get accumulated in the environment on special landfill sites, at best. Many of them penetrate into the atmosphere, soil and natural water. All the existing practically implementing methods of removal of such substances, which include sorption, ion exchange and membrane treatment – have one essential disadvantage: using them purifies one medium but pollutes another, no matter the concentrated form.

Photocatalytic treatment lies in organic substances’ total decomposition on catalysts under exposure to ultraviolet emission (artificial ultraviolet or sunlight) till carbon dioxide and water as well as other elementary substances. The same process occurs with organic pollutants naturally, though without any catalysts. POPs require a very long period of time to decompose.

Why haven’t photocatalysts been widely implemented yet?

2. First of all, suchlike highly efficient materials themselves originated recently – just in the last 10-15 years. Secondly, high efficiency of catalysts is ensured by the small size of the grains. The most efficient commercial catalyst is Evonik P25 (Germany), which has grains sized 50 to 70 nm. Such a catalyst is very hard to remove out of water after its purification. Therefore, treatment of large amount of water is very expensive.
3. Over the last several years, a method has been proposed which assumes creation of granules of some inert material filled with nanoparticles of the catalyst. Size of the latter may be reduced to 5 nm, which will provide high activity of the material. The size of granules may be increased up to 1,5…2 mm. Such granules can be extracted from purified water in a usual sediment basin. After the use, the photocatalyst is going to be returned to the beginning of purification process. No regeneration is required. Granules are going to operate in the water until their total abrasion.
4. It is necessary to develop a method for obtaining the granules maximally saturated with the catalyst’s nanoparticles, the activity of which mostly effects organic pollutants.

Possibilities:

There is every necessary infrastructure at the disposal of the Faculty of Chemistry and in the Nanotechnology Research and Education Centre needed to complete these tasks. There is collaboration with the University of Oviedo (Spain), which resulted in 5 publications in Top-10 journals and 2 PhD dissertations defended in Spain by SUSU staff members. There are more than 20 articles on obtainment of new photocatalysts published in Top-25 journals (indexed in Scopus and Web of Science), including 3 articles published in the journals which are the leaders of their rating. There are 5 Candidate’s, two Doctoral and 2 PhD dissertations defended at the University of Oviedo.

Result/ Product

The result is a method used to obtain a composite photocatalyst based on TiO2/SiO2, the properties of which are modified so that it completely removes phenol and its derivatives out of industrial water of the cake—chemical manufacture. Another result is the brand-new water treatment technology.

Consumers of the Result / Product

Consumers of the result/ product are enterprises specialized on metallurgy, such as PJSC Magnitogorsk Iron and Steel Works, JSC Mechel, PAO Severstal, PJSC NLMK, etc. Implementation of the project will allow for a total removal of phenol – one of the strongest toxic agents in the list of POPs – from industrial water of the cake-chemical manufacture, which will essentially reduce the negative impact on the environment and population.

Description of the project

1. Analysis of literature on the issues regarding the control over selectivity of photocatalysts.
2. Synthesis of photocatalysts on the basis of TiO2/SiO2, which are characterized by high activity and selectivity in relation to phenol and cyanides.
3. Exercising the process of phenol and cyanides’ photodestruction with the use of model water and the real industrial water of PJSC Magnitogorsk Iron and Steel Works.
4. Studying kinetics of photodestruction and kinetics of the catalyst granules’ sedimentation.
5. Development of the mathematical model of the processes of water purification and extraction of the catalyst’s grains.
6. Theoretical and experimental obtainment of the optimal operational characteristics of the granules.
7. Publishing articles in Top-25 issues indexed in Scopus and Web of Science databases.
8. Defenses of Bachelors’ and Masters’ graduation theses.
9. Calculation, development of the structure and production of a trial water purification plant according to the requirements of PJSC Magnitogorsk Iron and Steel Works.
10. Implementation of the developed technology at PJSC Magnitogorsk Iron and Steel Works.
11. Developing the technique to modify the surface of the catalysts in order to impart them with the required properties (catalytic activity, selectivity towards certain pollutants, etc.).
12. Patenting the results.
13. Development of a line of catalysts, the properties of which are adjusted for certain industries.
14. Engagement of other industrial partners.
15. Establishment of a hi-tech enterprise for production of the catalysts.

Project value

Project implementation timeline

01.09.2019 – 30.06.2022

Key milestones of the project

Target parameters of the project

Key partners of the project

The number of contracts (letters of intent) signed with the key industrial partners

1. A letter of intent has been signed with PJSC Magnitogorsk Iron and Steel Works

Coordination of the research project with the events held within national projects and state programmes

Ecology National project

Assessment of the current project level by such parameters as “research”, “innovations”, “manufacture”, “market”

The scale includes 10 points (0 is the minimum, 10 is the maximum)

Parameters:

research - 10

innovations - 10

manufacture - 2

market - 2