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LISE APPELS: PAVING THE WAY FOR GREEN CHEMISTRY
How can chemicals and plastics become sustainable, climate-friendly and part of the circular economy? Renewable energy and decarbonisation alone will not suffice, because organic chemistry remains based on carbon. According to Lise Appels, Professor of (Bio)Chemical Conversion Processes at the De Nayer Campus, the solution must be sought in renewable carbon, the key to Green Chemistry.
First, some history. In 2022, a groundbreaking paper was published, entitled ‘Renewable Carbon as a Guiding Principle for Sustainable Carbon Cycles’. The article contained the core ideas of what has become known as the ‘Renewable Carbon Concept’. “Fossil carbon should eventually be completely replaced by renewable carbon from alternative sources such as biomass, CO2 and recycling”, Lise explains. “This challenge touches on the essence of the problem of climate change and global warming: the emissions from the combustion of fossil resources. Industry is therefore encouraged to replace fossil resources with renewable carbon. For the chemical and materials industry, this means the biggest transformation since the first industrial revolution.”
Resource recovery
Lise Appels graduated in 2006 as a Bioengineer at the University of Antwerp. As a specialist in Environmental Technology, she was immediately able to start working at the De Nayer Campus in a research project on the disinfection of cooling water circuits. This was the prelude to her doctoral work at the Faculty of Engineering Science of KU Leuven on the anaerobic digestion of sew- age sludge to biogas consisting of methane and CO2. After two years of postdoc, Lise became an assistant professor at the De Nayer Campus in 2013. Since 2023, she has been a full professor and head of the Education and Research Unit Chemical Engineering Technology. Lise teaches, among other things, Environmental Technology, Industrial (Organic and Inorganic) Chemistry and Green Chemistry. She also leads the research group Chemical and Biochemical Reactor Technology and Safety ( CREaS De Nayer). This group is active in the field of resource recovery and the production of renewable chemicals and energy carriers from waste, side streams and biomass. This involves advanced (photocatalytic) wastewater treatment, optimization and design of mixed culture microbial processes and the production of renewable chemicals by thermal, chemical and biochemical conversion technologies.
Lise’s own research follows two main lines. The first line is the biological valorisation of organic waste streams such as polluted wastewater, manure and sewage sludge. “Mixed cultures are very robust and versatile. Via the alteration of process conditions, in combination with the use of advanced structural materials, we optimize our processes towards the recovery of renewable energy carriers such as biogas (CH2) and H2 and renewable chemicals such as carboxylic acids ammonia.”
Antibacterial components
In her second line of research, Lise and her colleague Professor Raf Dewil work with more solid forms of biomass. Her team develops innovative microwave and ultrasound-based processes for converting them into high-value chemicals. A good example of this is the EXACT project that Lise set up with Geert Potters, head of research at the Antwerp Maritime Academy. “During the PhD of Nick Sweygers, we developed an innovative extraction process based on ultrasound and microwaves which we patented later on. This process is the basis for the EXACT-project, where we extract antibacterial components from brown seaweeds”, Lise explains. “These components can be used to make the coatings of ships less toxic to the environment.”
It goes like this. The hull of a ship that is under water must be protected against corrosion and the growth of sponges and shellfish that slow down the ship’s speed. The coatings used for this contain substances that are harmful to marine life. By using protective coatings with natural antibacterial components, no more toxic substances are released into the water that could ultimately end up in our food.
High purification
“Our patented process allows us to extract specific components with a very high degree of purity”, says Lise. “Brown seaweed is abundant in the North Sea. We can use a large part of the biomass for extraction. What remains can be for example digested to generate a form of renewable green energy. This leaves hardly any waste. In this way, we kill two birds with one stone: valuable extraction and renewable energy. And we are one step closer to Green Chemistry.”
Yves Persoons
