Lignin structure and function
The lignin structure suggests that has the potential to be the main renewable source for aromatics and represents an excellent raw material alternative for the production with high added value compunds such as chemicals, polymers and new materials.
One of the main challenges that arise when investigating possible uses and applications of lignin is still its poorly defined chemical structure and functional adaptability. Both are dependent of the lignocellulosic raw material (hardwood, softwood or herbaceous material), as well as the separation and fragmentation processes used.All together, determine the physicochemical properties of the lignin narrowing or increasing its potential uses.
” 50 million tons of lignin are produced every year, mainly from the pulp and paper industry.
Currently, around 50 million tonnes of lignin are generated every year, coming mainly from the pulp and paper processes. Of those, only 4 % goes to other uses different than power generation, which is a low value recovery thereof.
Traditionally, commercial lignins obtained from paper production are known as kraft lignin or sulfonated lignin. However, due to the boom in biofuels, and more particularly the second generation bioethanol, it is expected to have another great alternative kind of lignin that would allow, on the one hand, to create new products from theco-streams (market and portfolio diversification) and to increase the profitability of technologies where, the lignin is generated.
Lignin is being considered as one of the most promising raw materials from renewable sources.
At present, there are commercial products with acceptable value that incorporate lignin in their composition as adhesives, dispersants, plasticizers and additives that are mainly used for construction chemicals and animal feed. However, thanks to their particular properties, lignin is a perfect candidate to be used for higher value applications (more than 900 €/t), such as production of resins (phenolic and polyurethane), phenols, natural antioxidants and composites, among others.
Currently, the research on lignin is focusing its efforts on discovering new uses of high added value; that will allow the increment of the annual growth rate of products where the lignin is implied.
Therefore, this is leading to consideration of lignin as one of the most promising raw materials from renewable sources, “lignin is a rising star“.