Advanced Oxidation Processes (AOPs)
Laboratory of Green Chemistry has a strong research background in the field of chemical oxidation. Novel materials and methods are studied in order to improve existing processes by keeping both applicability and cost-efficiency in mind. Scaling-up and commercialization are considered important in the projects.
Chemical oxidation includes the technologies based on:
- Ozonation (O3)
- UV light with oxidants (e.g. hydrogen peroxide)
- Fenton mechanisms
- Catalytical oxidation
- Advanced oxidation nanotechnology
- Photocatalysis under visible light
- LED-based photocatalysis
- Different combinations of these treatment technologies
The advantages of chemical oxidation are:
- disinfection (bacterias, molds, viruses, biofilm)
- enhancement of processes
- oxidation of toxic and refractory compounds
- minimizing the sludge production
- the improvement of biological processes
- sum effects (e.g. colour, odour, microbes, toxicity, organics)
Advanced Oxidation processes
The processes that are based on the utilization of secondary oxidants, such as hydroxyl radicals are called advanced oxidation processes (AOPs). AOPs have been suggested for example for the treatment of landfill leachates and biorefractory organic pollutants, such as aromatics.
By AOPs it is possible to oxidize a larger spectrum of compounds, by the highly reactive and unselective radical pathway than by direct ozonation. The generation of hydroxyl radicals (.OH) can be considerably intensified via various combination of oxidants, radiations and catalysts.
Ongoing research in laboratory
Nanotechnology in advanced oxidation process; a green process for the treatment of toxic organics present in water and wastewater
In this project catalysts used for photodegradation are prepared by methods of nanotechnology. Nanosize and nanostructured semiconductors are of particular interest because of their environmentally friendly features. In general, due to rapid OH-radical based oxidation reactions, photocatalysis by nanocatalysts is characterized by high reaction rates and short treatment times. Other advances are that toxic intermediate products are not formed and pollutants can be degraded in ppb level when no further treatment is necessary.
LED-based photocatalysis for water treatment
The aim of the project is to enhance the photocatalytic water treatment. UV-lamps are replaced by long-lasting, mechanically stable, and environmentally safety LED-lamps (light emitting diodes) and catalytic thin films used as photocatalysts. ALD-technique (atomic layer deposition) or sol-gel dipping methods are used in thin film preparation.
Disinfection by UV-LED radiation
The target of the project is to investigate the disinfection of water, air, and surfaces by UV-LED radiation.
Hybrid membrane process for water treatment
In this project photocatalytic membranes operating in the visible light region are prepared and their efficiency tested under LED-radiation.
Sonoelectrocatalysis in water treatment
The objective of this research is to develop novel metal oxide electrodes for combined sono- and electrocatalytic treatment of low- and non-transparent wastewaters leading to complete mineralization of organic pollutants. Also, aim is to enhance the efficiency of catalysis by increasing the specific surface area of electrodes and changing the chemical composition of their top layers. The use of low cost substrates and precursors is another goal of the study.
- Catalytic Degradation of Persistent Organic Pollutants
- Sonochemically-assisted Electrochemical Treatment
- Nanolyst – Nanostructured materials for Catalytic Oxidation
- Novel Materials and Systems for Degradation of Organic Pollutants
- AOP´s in Treatment of Pulp and Paper Mill Wastewaters
- UV LED and ALD-coated Photocatalysts in Water Treatment
- Novel micro- and nanostructured semiconductors and their photocatalytic properties
Examples of case studies done in the laboratory:
Integrated technologies for the treatment of contaminated soils (PAHs, CPs, Syanides), ground waters and industrial landfill leachates
Ozone treatment of circulation waters and effluents in the pulp and paper industry – removal of resin acids, EDTA and microorganisms
Impact of ozonation on the colour and COD of pulp and paper mill waters
Inactivation of microbes and fungus in a Finnish fish farm (O3, UV ja H2O2)
The oxidation of malodorous odours from compost (prestudy)
The oxidation of quicksilver wastes (prestudy)