The doctoral dissertation in the field of Chemistry will be examined at the Faculty of Science, Forestry and Technology, Joensuu campus and online.
What is the topic of your doctoral research? Why is it important to study the topic?
The idea of the research was studying industrial waste, developing green technologies utilizing waste as raw material and monitoring microplastic pollution. The research had three aims: firstly, to synthesize zeolites out of waste incineration fly ash to enable recycling of fly ash waste into cheap catalytic materials. Fly ash is currently among the biggest waste resources in the world and conversion into useful zeolites would recycle a large amount of this waste.
Secondly, to prepare artificial microplastics that accurately represent real world samples and use them to test methods that we use for microplastic detection. This is necessary because right now, methods are tested with standardized polymer beads that are idealized and do not accurately represent real microplastic particles. This ensures better accuracy of research.
The final aim was to develop an analytical protocol to study industrial wastewater samples. Industrial samples are currently very understudied and do not have a universal protocol for sample preparation and analysis. This gap must be filled in order to have comparable results between laboratories, accurate measurements and data on the contribution of the industrial sector to microplastic pollution.
What are the key findings or observations of your doctoral research?
Fly ash zeolites can be prepared from municipal waste incineration waste fly ash and they show promising results for future use for instance as catalysts in industrial processes or even to remove microplastics from wastewaters. If this technology is further developed, large amounts of fly ash waste could be recycled.
Artificial microplastics accurately represent microplastics found in environmental and industrial samples. A grinding protocol for everyday polymers was created to ensure consistency and comparability between analytical laboratories in the future.
The digestion protocol developed for industrial samples offers shorter analysis times compared to current methods, it is a universal procedure that works on a very wide array of samples and enables companies to better monitor their microplastic pollution in the future.
How can the results of your doctoral research be utilised in practice?
This study's results may have several benefits for the industrial sector. A company may be able to use fly ash from one process, produce zeolites from it, which they can use as catalysts for another process. Companies can monitor their microplastic pollution and satisfy future law regulations more efficiently. The two technologies can even be combined, and fly ash zeolites can be used to remove microplastics from industrial wastewater.
What are the key research methods and materials used in your doctoral research?
The research was done in close collaboration with the industry. There was a joint effort with the industrial sector to develop efficient methods that benefit the industry. Municipal waste incineration fly ash was obtained from a waste incineration plant and inorganic chemistry was utilized for producing the zeolites. Different synthesis parameters were studied to determine their effects on the production of zeolite.
Then, those zeolites were characterized via common analytical methods (microscopy, X-ray diffraction, adsorption/desorption tests, surface area measurement...) and compared with commercial references. Synthesized zeolites showed increased surface area, increased porosity, and signs of comparable catalytic activity to commercial zeolites. To prepare artificial microplastics, common everyday polymers were obtained in the shape of beads, which were cooled in liquid nitrogen and grinded into microplastics with a polymer mill. The resulting particles were then used to test common microplastic detection methods (Fourier Transform Infrared Spectroscopy and Raman spectroscopy). Microplastics were prepared in many size ranges even down to nanoscale and thus, the produced particles can be used in future method development.
The industrial samples were obtained from the respective facilities, and we developed a universal sample preparation protocol that utilizes various enzymes and hydrogen peroxide. Then, the samples were analysed using IR spectroscopy to get microplastic content of the industrial samples. The developed digestion protocol significantly reduced processing time compared to protocols used for environmental samples and was universally applicable on all the diverse samples obtained in this study.
The doctoral dissertation of Blaž Hrovat, MSc, entitled Industrial waste management: Fly ash zeolites and microplastics will be examined at the Faculty of Science, Forestry and Technology, Joensuu Campus and online. The opponent will be Professor Satu-Pia Reinikainen, Lappeenranta-Lahti University of Technology, and the custos will be Research Director Arto Koistinen, University of Eastern Finland. Language of the public defence is English.
For more information, please contact:
Blaž Hrovat, blaz.hrovat@uef.fi, tel. +358 50 473 8825
