Professor Emeritus Herbert Sixta: “The most important task of a professor is to educate young people, to help them build their career”

After an extensive career in academia and the forest-based industries, Professor Herbert Sixta has retired. Having worked in Austria for 25 years, Sixta arrived to Aalto in 2007, where his research in biorefineries helped create, among other things, the Ioncell process, a technology that turns used textiles, pulp, and paper into new textile fibres sustainably and without chemicals.
A portrait of professor emeritus Herbert Sixta.

Sixta completed his habilitation at GUT (Graz University of Technology) in 1995, in the field of Chemical Pulping. A year later, he began working there as an Associate Professor in Wood, Cellulose, and Pulp Chemistry. Alongside his work in academia, he also built a career at the industry.

“I had a long career in a relatively large company that produced regenerated cellulose fibres and pulp in different grades. I had been working at the company during summers already and it was close to the place where I was born and raised, so it was a rather natural development for me”, Sixta says.

At the end of the 1970s, the awareness of environmental issues at companies was not yet pronounced. Sixta started his career as an industrial chemist, in a newly-found environmental department. The employees of the company managed to convince the managers that environmental issues would become increasingly relevant in the coming years.

“Starting in such a department, I had the opportunity to learn of many other areas of a large company, because everything was affected by environmental problems. Therefore, I had a good overview of things like production processes and product portfolios, and I could gather quite a large knowledge in the area of wood-based products.”

From Austria to Finland

After 25 years of working in Austria, Sixta was offered a professorship of chemical pulping at TKK in 2006, which soon became a part of Aalto University. He was one of the few persons to have been offered a professorship at TKK with an invitation, without a formal application.

“At first, I assumed they could not compete with my salary, as I was already in a managerial position at my company. But they did not give up, and after a year of contact, I accepted a kind of dual position in which I would still spend 25 % of my time at the company in Austria.”

From October 2007 onward, Sixta would spend one week a month in Austria and otherwise work in Finland. This arrangement was maintained after he quit his job at his company five years later to focus solely on his work at Aalto.

In 2009, the professorship was renamed to Biorefineries, to more accurately describe the research that was being done.

“The name was an analogy to an oil refinery. We wanted the name of my research group to reflect how a multitude of different products is produced from one raw material. Instead of crude oil, sustainable raw materials such as lignocellulose in general or wood in particular are used.”

The time is now to develop better products from sustainable raw materials like wood and other lignocellulosic materials.

Herbert Sixta

How the Ioncell project was born

In addition to several patents and publications in novel biomass fractionation methods, Sixta is one of the inventors of Ioncell® process. Ioncell is a technology that turns used textiles, pulp and even old newspapers into new textile fibres sustainably and without chemicals.

Sixta and his team of researchers have worked on Ioncell in close collaboration with a team of organic chemists at the University of Helsinki, led by professor Ilkka Kilpeläinen. Over the years, the two teams have been persistently developing the process.

The original idea for Ioncell emerged as a response to the economic pressure on the forest industry in Finland. As newspapers and the writing paper market went down due to the competition by electronic devices, a nationwide research funding hub was founded. The goal was to develop new sustainable forest-based products.

“There was very generous funding and I had the privilege of being part of this undertaking. Over the years, we launched projects for two or three years at a time and developed our ideas. So, we had ample time for going through all the necessary developmental steps in building what would later become Ioncell”, Sixta says.

In 2013, the research team had a major breakthrough when they succeeded in showing that the Ioncell process is capable of producing high-quality textile fibres. This increased the visibility of their research and they were able to attract excellent students to carry out their dissertations as a framework for the development of the Ioncell process in Sixta’s group.

“It took quite a long time to prove that we can not only produce the fibres, but also keep the process as a closed-loop operation. This means that the solvent we use in the process, ionic liquid, can be reused many times and the losses of solvents are minor and not relevant to the environment.”

Professor Emeritus Herbert Sixta and members of the Ioncell team posing beside a Ioncell spinning machine
Ioncell has received funding from Aalto University for the design and construction of a pilot plant, which has now been in operation for about a year. In the pilot plant, the Ioncell process will be developed as a continuous commercial process.

It is important to do work that can serve society

When asked for advice for young professors, Sixta emphasises how important it is to work on subjects that serve society. Specifically, the change from a crude oil economy into a bioeconomy needs to be facilitated.

“We need to join forces to really enable the shift to a bioeconomy. We are currently witnessing this dependency on crude oil also due to the war in Ukraine. We could have seen it earlier, but it was cheaper to turn a blind eye to the problem. The time is now to develop better products from sustainable raw materials like wood or other lignocellulosic materials, such as wastes”, Sixta says.

Sixta also believes that we need to support the industry so that new sustainable processes can be implemented in time, and not decades later. Research projects in the bioeconomy are often not targeted enough, too fragmented or designed past the needs of our society, so that the innovation density is too low to develop sustainable, economically relevant processes to market maturity.

This is also an appeal to funding institutions to pay more attention to ensuring that research proposals are coherent in terms of sustainability and economic relevance and are oriented towards the needs of our society. Of course, this also means that longer development periods must be funded for projects that meet these requirements.  

“All my graduates have received excellent jobs, because this knowledge in textile chemistry has become rare. If you understand the chemistry of wood, especially that of the polymeric components, you at least have the basis for developing processes to convert lignocellulose into chemical products in general. This knowledge was available in Finland and Sweden for many years, but was lost through short-sighted decisions by companies when, for example, the viscose industry in these countries was shut down and at the same time this basic knowledge was not further promoted in research, so that the basis for the successful development of new processes was lost", Sixta says.

The textile industry is currently the second-largest polluter in the world, right after the oil industry. It is therefore crucial that we develop new sustainable processes. This need is reflected in the popularity of Ioncell.

“Ioncell seems to be very attractive to young researchers. I get applications all the time from scientists all over the world who wish to work in our team. This is because they see that we are working on something that could be useful to society.”

Young professors should learn about the industry

Sixta also thinks young professors should learn how to interact with companies. This is especially vital for researchers at technical universities.

“The younger professors who come strictly from academia and may not know what to expect from companies. This is something I often tell my young colleagues – please go work in the industry for half a year and do some work with companies. It is very important to get to know them, to understand their needs, and learn how to collaborate in the best possible way.”

In retirement, Sixta becomes a professor emeritus at Aalto. He intends to take on an active role.

“One of the main reasons why I want to stay at Aalto as an emeritus professor is that I want to be reachable by students, so they can contact me and we can have discussions, I can visit them in the lab, give them advice, and support them within my possibilities. The most important task of a professor is to educate young people, to help them build their career.”

Sixta encourages students to expand their horizons, to not restrict themselves in their life. It is a necessity to stay open to learning new things.

“You have to explore and enjoy different areas, not only your closest neighbourhood. It is also important to not be afraid to contact people that you think can offer you useful input. Please don’t hesitate to ask questions! That is my general advice to students: keep your eyes open.”


  • Professor in Biorefineries at Aalto University since 2007 and Associate Professor in Wood, Cellulose and Pulp Chemistry, GUT (AU) since 1996.
  • Has over 30 years of experience in industrial research on pulp and cellulose chemistry.
  • Head of the Department of Bioproducts and Biosystems at Aalto University during 2014-2020.
  • Other interests include photography, hiking and history. Intends to spend some of his increased free time in retirement hiking with his family and exploring different regions and cultures.
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