Department of Bioproducts and Biosystems


Biorefineries research group is led by Emeritus Prof. Herbert Sixta. The group's research covers the entire value chain from the fractionation of the lignocellulosic biomass to valorization of the isolated biopolymers, with the aim of sustainably producing commodities analogous to fossil-based products.
CHEM_Bio_Marianna_Granatier_From wood to fiber
Marianna Granatier, From wood to fiber

Research themes:

1. Biomass fractionation - chemical pulping refineries and novel fractionation processes:

We investigate radically new energy and resource efficient production technologiesfor chemical pulping, e.g. Kraft-Oxygen Delignification (KrOxy) process and new dissolving pulp technologies.In addition, our research group develops novel biomass fractionation processes based on the utilization of Biomass valorisationsupercritical water and green solvents, e.g. gamma-valerolactone (GVL).


2. Biomass valorisation:

Cellulose: We study conversion of cellulose e.g. into man-made cellulose fibers and all-cellulose composites.

Hemicelluloses: Our research topics include the valorisation of xylan from alkaline extractions, production of xylo-oligosaccharides and catalytic conversion of biomass-derived sugars into furans.

Lignin: Lignin is an interesting biomass component which can be converted into valuable products such as bio-oil. Lignin-cellulose blends can be used e.g. as precursor fibers for carbon fibers, or as natural dye in textiles.

Our versatile reactor portfolio enables flexible pulping experiments from small lab-scale (30 mL) to pilot scale (10 L), including both traditional (prehydrolysis) kraft and novel Organosolv processes. Elemental-Chlorine-Free (ECF) and Total-Chlorine-Free (TCF) bleaching techniques are readily available.

Our flagship research in biomass valorization is the production of novel man-made cellulose fibers for the circular economy by the dry-jet-wet spinning Ioncell® process, which convert cellulose from virgin wood pulp or cellulosic textile waste into high-quality, high-strength textile fibers. In addition, our research group is equipped with fiber characterization equipment and yarn spinning machinery. We also investigate in the conversion of extracted hemicelluloses and lignin to high value products such as furanic platform chemicals, monoaromatic compounds and bio-oil. Our lab developed advanced chromatography methods (HPLC, CE, IC, GPC) for comprehensive analysis of complex product mixtures.


Examples of ongoing research projects:

  • Trash-2-Cash (EU Horizon 2020)
  • SolvRec (Business Finland)
  • iCom (Business Finland)
  • ALL-CELL (FiDiPro, Prof. Tatiana Budtova)
  • WoCaFi (ERC starting grant, Dr. Michael Hummel)
  • Tekide (ERDF)

ALL-CELL: From ultra-light to ultra-strong all-cellulose composites via green processing

Finland Distinguished Professor grant awarded to Prof. Tatiana Budtova (Center for Materials Forming of MINES ParisTech, France). The goal of the 4-year project (started 2016) is to imagine, prepare and characterize new fully bio-based materials, all-cellulose composites.

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Feng Chen, Tatiana Budtova and Oona Korhonen - ALL-CELL team. Photo by Eveliina Jutila
Aalto University / Ioncell logo


Ioncell-F is a technology that turns used textiles, pulp or even old newspapers into new textile fibers sustainably and without harmful chemicals. The process converts cellulose into fibers which in turn can be made into long-lasting fabrics.

Read more about the Ioncell process and our projects at!

Twitter: @IoncellFibers


The Ioncell-F process was granted the Global Change Award 2016 by the H&M Conscious Foundation, the Paper Recycling Award 2015 of the European Recovered Paper Council (ERPC), and the DIA Innovation Award 2018.

Ioncell fibers:

President Sauli Niinistö and Jenni Haukio at 2018 Finnish Independence Day reception. Photo: Vesa Moilanen/Lehtikuva

Mrs. Jenni Haukio’s gala dress in the Independence Day Reception 6.12.2018; photo: Vesa Moilanen, Lehtikuva. Textile design: Helmi Liikanen (ARTS), dress design: Emma Saarnio (ARTS)

CHEM_Bio_Ioncell_from jeans to scarf

A scarf made of Ioncell® fibers from recycled waste cotton and given to president Macron

CHEM_Bio_IOncell Marimekko dress

Marimekko’s Unikko dress. It was produced form Ioncell®/Tencel™ blend woven fabric. Photo: Sebastian Johansson, dress design: Riikka Buri, Marimekko

CHEM_Bio_Ioncell dress group

The Ioncell dress group

γ-valerolactone biorefinery

γ-valerolactone pulping is a novel organic solvent fractionation process developed by Professor Herbert Sixta’s Biorefineries research group.

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GVL biorefinery Photo: Aalto University / Anni Hanén
CHEM_Bio_Herbert Sixta

We urge not only for investment in pulping research, but also for the commitment of young researchers.Together we make pulping great again!

Herbert Sixta, head of the research group
Ioncell thread on four different colors

The textile industry needs sustainable fibers produced from renewable or recycled sources, which can be recycled at the end of their life and which do not produce micro-plastics.  The demand for textile fibers is growing due to population growth and living standards. Currently, most textile fibers are synthetic, e.g. polyester, and are made from non-renewable sources. Cotton cultivation causes environmental problems due to the high consumption of irrigation water, pesticides and fertilizers. When textiles made of synthetic fibres are washed and worn, small fragments are released, causing microplastic contamination.

Aalto University offers the opportunity to study the raw material chemistry and process engineering necessary for the development of a sustainable textile industry, thereby combining materials research with textile and fashion design.

Production of commodities from biomass is the most viable option in the foreseeable future to mitigate the climate changes.

The raw materials of novel man-made cellulose fibers that we are developing in our research group are virgin pulp and recycled cotton waste. Cellulose pulp is made from smaller trees, and thinning stimulates the growth of remaining trees, thereby increasing carbons storage. When pulp is used for long-lasting products like textiles, the carbon is stored in the product. The recycling of cellulosic textiles even prolongs the carbon sink

CHEM_Bio_Biorefineries group

Related content:

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.

Biorefineries and Herbert Sixta in spotlight at 2022 seminar

Biorefineries research group annual seminar presented the latest developments in forest-based, sustainable refineries and analytical tools.

Herbert Sixta presents at the Biorefineries Annual Scientific Seminar 2022

Fibre made from recycled cloth towels and hemp stronger than cotton

The tensile strength of fibres created with the Ioncell method is up to 2.5 times more than that of cotton, while an Ioncell knitted fabric made from recycled hemp withstands abrasion for twice as long as normal hemp fabric.

Ioncell-kuituja kierrätysmateriaalista

Solving the systemic challenges in textile and fashion industry

We need systemic and fundamental changes in the textile and fashion industry’s business model, including a deceleration of manufacturing and the introduction of sustainable practices throughout the supply chain; decreasing clothing purchases and increasing garment lifetimes.

We need systemic and fundamental changes in the textile and fashion industry’s business model.

Take Finland’s lead and choose clothes you don’t have to feel guilty about

An Aalto University-designed and -produced dress made of birch trees shows how one day we will all look—and feel—good in sustainable fabrics

Haukio and Niinistö. Photo: Vesa Moilanen/Lehtikuva

Jenni Haukio to wear gown made of sustainable Ioncell material at December’s Independence Day reception

Ioncell is a new technology that creates high-quality textile fibres from wood or recycled materials.

Aikaisempi Ioncell-lankoja

President Macron received a scarf made from old jeans with Ioncell-F technology

The sustainable textile process was introduced to the President during his visit to Aalto University on 30 August 2018.

Professor Herbert Sixta presented Marimekko fabric made with Ioncell-F technology to President Macron, Finland’s Prime Minister Juha Sipilä and Aalto University President Ilkka Niemelä. Photo: Aalto University/Mikko Raskinen

”Koivikko” scarf paving way for new textile fibres made out of renewable and traceable birch

Professor Herbert Sixta donated an Ioncell scarf to Sirpa Välimaa, Product Manager Dissolving Pulp, Stora Enso Oyj, in PulPaper Conference on 31 May in Helsinki.

Professor Herbert Sixta and Sirpa Välimaa. The scarf was donated to Sirpa Välimaa as an expression of gratitude for Stora Enso's great support for Ioncell process over many years. Photo: Sofi Vuojakoski

High performance man-made cellulosic fibres from old newspapers

Increasing consumption requires new ways to recycle waste. In Aalto University old newspapers were converted to textile.

Upcycling ‘fast fashion’ to reduce waste and pollution

Aalto’s Ioncell team presents their work at a meeting of the American Chemical Society.

Fibres from textile waste to be turned into new attractive consumer products

Trash textiles are a valuable resource that should not be left untapped. Aalto and VTT are participating in an EU project called Trash-2-Cash.

Awarded method makes textile fibre from waste cotton

A greener textile industry requires expertise in chemistry, design and economy, stresses Herbert Sixta who leads the development of Ioncell-F.

A process revolutionising cotton recycling wins the H&M Global Change Award

The Ioncell-F™ process adapted for the conversion of waste-cotton into new textile was awarded as one of five winners among 2,700 proposals.

Luxury fibre from recycled cardboard

Prize-winning spinning method can reduce the environmental hazards of textile production.

Ioncell kierrätyspahvista

Latest publications:

A novel X-ray diffraction approach to assess the crystallinity of regenerated cellulose fibers

Luigi Gentile, Herbert Sixta, Cinzia Giannini, Ulf Olsson 2022 IUCrJ

Conversion of bleached soda bagasse paper-grade pulp to dissolving-grade pulp using different hemicelluloses removing post-treatments with emphasis on IONCELL-P process

Kajal Moradian Gilan, Sahab Hedjazi, Huy Quang Lê, Ali Abdolkhani, Sara Ceccherini, Mira Viljanen, Herbert Sixta 2022 Holzforschung

Base-catalysed depolymerization of lignins in supercritical water: Influence of lignin nature and valorisation of pulping and biorefinery by-products

Eduardo Pérez, Nerea Abad-Fernández, Tainise Lourençon, Mikhail Balakshin, Herbert Sixta, María José Cocero 2022 Biomass and Bioenergy

Application-Related Consideration of the Thermal Stability of [mTBDH][OAc] Compared to Amidine-Based Ionic Liquids in the Presence of Various Amounts of Water

Inge Schlapp-Hackl, Joanna Witos, Krishna Ojha, Petri Uusi-Kyyny, Ville Alopaeus, Herbert Sixta 2022 Industrial & Engineering Chemistry Research

Nanoporous Carbon Electrodes Derived from Coffee Side Streams for Supercapacitors in Aqueous Electrolytes

Julian Selinger, Sebastian Stock, Werner Schlemmer, Mathias Hobisch, Nikolaos Kostoglou, Qamar Abbas, Oskar Paris, Christian Mitterer, Michael Hummel, Stefan Spirk 2022 Nanomaterials

High-purity cellulose production from birch wood by γ-valerolactone/water fractionation and IONCELL-P process

Shokoufeh Shokri, Sahab Hedjazi, Huy Quang Lê, Ali Abdulkhani, Herbert Sixta 2022 Carbohydrate Polymers

Coffee Waste-Derived Nanoporous Carbons for Hydrogen Storage

Sebastian Stock, Nikolaos Kostoglou, Julian Selinger, Stefan Spirk, Christos Tampaxis, Georgia Charalambopoulou, Theodore Steriotis, Claus Rebholz, Christian Mitterer, Oskar Paris 2022 ACS Applied Energy Materials

The effect of temperature on the electrical and thermal conductivity of graphene-based polymer composite films

Ali Tarhini, M. Walid Alchamaa, Massoud Khraiche, Michel Kazan, Ali Tehrani-Bagha 2022 Journal of Applied Polymer Science

Evaluation of Keratin-Cellulose Blend Fibers as Precursors for Carbon Fibers

Hilda Zahra, Julian Selinger, Daisuke Sawada, Yu Ogawa, Hannes Orelma, Yibo Ma, Shogo Kumagai, Toshiaki Yoshioka, Michael Hummel 2022 ACS Sustainable Chemistry and Engineering

The fiber-matrix interface in Ioncell cellulose fiber composites and its implications for the mechanical performance

Mindaugas Bulota, Simona Sriubaite, Anne Michud, Kaarlo Nieminen, Mark Hughes, Herbert Sixta, Michael Hummel 2021 Journal of Applied Polymer Science
More information on our research in the Research database.
Research database
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