As part of Helsinki Design Week, FinnCERES research is widely presented at the Designs for a Cooler Planet exhibition. In the FinnCERES "Clean air and water" theme, we are seeking for solutions to remove microplastics and pharmaceutical residues from wastewaters utilizing bio-based materials.
Microplastics and pharmaceutical residues are notorious villains in our water systems. Scientists at VTT and Aalto have developed wood-based materials to tackle these nasty problems: a filter that can capture the smallest microplastic particles and a yarn that can capture harmful hormonal residues, both made possible with nanocellulose.
A thousand litres of seawater can contain up to 8.3 million particles of microplastics. Until now, identifying these very small particles has been difficult – usually they are only detected once they have accumulated in the bodies of fish. A method developed at VTT utilises nanocellulose structures for early particle identification. Nanocellulose would allow particles to be captured even before they enter waterways.
The properties of nanocellulose films and hydrogels support the identification and capture of very small microplastic particles. “Nanocellulose has a mesh-like, porous structure and a large BET surface area. In the water, powerful capillary forces are generated in this structure, allowing particles to be transported inside the mesh and bound there”, says Research Professor Tekla Tammelin from VTT.
The method provides a way to catch microplastic particles of a size that the human eye cannot detect. These are particles with a diameter of only 100 nanometres.
“Nanocellulose structures can be used to identify and analyse these particles and to obtain information about their behaviour at an earlier stage. We can determine the concentration of particles in water and analyse, for example, whether particles are released into drinking water from plastic bottles "
Next step: filtration methods
The identification of microplastic particles with nanocellulose structures has been developed at VTT as part of the FinnCERES flagship project, which is exploring new bio-based material solutions. The next step could be to develop new and inexpensive filtration solutions utilising the method.
“New filtration solutions would allow particles to be captured where they are generated. The solutions could be utilised, for example, in laundry, where microplastic particles are released from fleece clothing and other synthetic fibres. Similarly, we could develop filtration methods for any industry where there is a risk of microplastics being generated and released into waterways.”
Fighting microplastics and pharmaceutical residues with nanocellulose. Samples of these important innovations are exhibited for the first time to the public at Aalto University Väre main entrance 2nd floor.
Wood-based yarn captures hormones from wastewater
Hormones and other pharmaceuticals ending up in bodies from natural waters are a globally significant environmental problem.
VTT and Aalto University have developed a wood-based cellulose fibre yarn that is an affordable solution for capturing pharmaceutical substances – especially ethinylestradiol in contraceptive pills – that would otherwise end up in bodies of water.
By attaching a cyclic sugar onto the surface of the cellulose fibre yarn, the research scientists were able to create a material that efficiently captures ethinylestradiol (EE2), a hormone used in contraceptive pills. The cyclic sugars are bonded chemically onto the surface of the yarn. The sugars form a pocket into which hydrophobic pharmaceutical substances seek to enter. This way, it only takes a few minutes for pharmaceutical compounds to become bound to the cyclodextrins coupled to the surfaces and cavities of the fibre. Test results demonstrate that one gram of fibre yarn can capture approximately 2.5 milligrams of the hormone.
'Hormone capture would be most effective in wastewater treatment plants and hospitals, since the wastewater in these facilities contains a higher concentration of the compounds. We are developing a wood-based affordable material that could be thrown into a tank in a wastewater treatment plant or used as a filter in a pipe connected to the tank. After some time, the material is collected mechanically. It is disposed of by incineration, but it is also possible to separate the pharmaceuticals and reuse the material,' describes VTT's Senior Scientist Hannes Orelma.
The development effort used wood-pulp-based fibre yarn that was manufactured using deep eutectic solvents (DES) in a method developed by VTT. DESes represent a new generation of organic solvents, some of which can be environmentally very friendly. This research used an environmentally friendly DES.
'It would be interesting to test how effectively the cellulose yarns can capture hormones and pharmaceuticals from wastewater at a larger scale,' states Orelma.
Hormones and other pharmaceutical agents ending up in bodies of water are a major problem in Central Europe and the United States, where the reported concentrations of oestrogen hormones have reached up to 0.83 micrograms per litre. These hormones are called endocrine disruptors, since they affect the gender of fish and turn male fish into females. The EU has identified pharmaceuticals in waters as a challenging problem, since wastewater treatment plants cannot capture the substances efficiently enough. At present, wastewater treatment plants capture pharmaceuticals by means of activated sludge tanks, but a portion of the compounds nevertheless escape the tanks and end up in bodies of water.
The development of the material started in 2015 as a collaborative effort between VTT and Aalto University. The development was funded by Tekes (currently known as Business Finland) under the Design Driven Value Chains in the World of Cellulose II project. At present, the design and development of the material is supported by the Academy of Finland and proceeds in the FinnCERES Materials Cluster that develops entirely new kinds of biomaterials. Clean air and water is one of the key research themes of FinnCERES.
