Plasma catalysis as an efficient and sustainable air purification technology
1 June 2016
UAntwerp, Campus Drie Eiken, Promotiezaal Q0.02 - Universiteitsplein 1 - 2610 Antwerpen-Wilrijk
Organization / co-organization:
Department of Bio-engineering Sciences
Karen Van Wesenbeeck
Silvia Lenaerts & Birger Hauchecorne
PhD defence Karen Van Wesenbeeck - Faculty of Science, Department of Bio-engineering Sciences
Our indoor air environment is two to five times more toxic than the outdoor environment while we spend as much as 90% of our time indoors. Inadequate ventilation, damp and mould damage, tobacco smoke, building materials, furniture, electronic equipment etc. cause increased concentrations of chemical compounds reducing the indoor air quality in homes, schools and other public places. The quality of the indoor air is thus an important issue for human health and comfort.
Non-destructive techniques such as mechanical and electronic filtration or adsorption are not sufficient for achieving a high indoor air quality. In recent years advanced oxidation processes (AOP) received growing attention due to their potential for degrading a wide range of pollutants at mild conditions. Non-thermal plasma technology is the AOP that is studied in this work. A particular advantage of plasma technology is its flexibility and ability to be combined with other technologies. Consequently, a more effective use of plasma is possible by exploiting its inherent synergetic potential through combination with heterogeneous catalysts. In the past decades, photocatalysis has gained more attention as an innovative and promising process for cleaning indoor air. The hypothesis is that by placing (photo)catalysts inside or in close vicinity of the discharge zone of a plasma reactor a synergetic effect of the two techniques can be obtained.
The main objective of this research is to study and deliver an innovative and efficient air purification technology by combining a direct current (DC) corona discharge system with a (photo)catalytic coating on the collector electrode in order to achieve a sustainable plasma catalytic system. In first instance a plasma reactor based on DC corona discharge is developed to study the degradation of nitrogen oxide (NO). Different parameters like humidity, voltage, polarity and configuration of the reactor are tested. A set of optimal conditions for the mineralisation of pollutants is defined by studying each parameter separately.
In the next part of the work, a suitable (photo)catalytic coating for implementation in plasma catalysis is optimised. The coating is based on the P25-powder-modi_ed-sol-gel method. The water, titaniumisopropoxide and diethanolamine content are studied. In the last part, plasma and (photo)catalysis are combined to obtain a plasma catalytic air purification technology. A new plasma reactor is built which allows to insert a UV lamp inside the unit. The decomposition effiiencies of the plasma unit with and without coating on the collector electrode and the synergetic effects are studied.
The final conclusions about this research of plasma catalysis as a sustainable and efficient indoor air technology can be summarised as follows:
- A set of working conditions for a self-developed DC corona discharge plasma reactor is found
- A suitable catalytic TiO2 coating is optimised for implementation in a plasma catalytic system
- The combined plasma catalytic system enhances the mineralisation of ethylene and diminishes the formation of by-products upon irradiation with an external UV source