What is Lignin – everything you need to know

The name Lignovations combines lignin and innovation which forms the core of our activities. For the reader unfamiliar with lignin, we have summarized everything you need to know about our favorite biopolymer, what it is, and how it can be useful in our lives.

Lignin – cellulose’s favorite sibling

You are probably familiar with cellulose which is used in paper production. Above all, it is the main structural material in the cell walls of plants and algae, but this is not the only material in plants. For example, wood is typically composed of 70% cellulosic carbohydrates (45% cellulose, 25% hemicellulose) and 25% lignin. But what is lignin and why should you care?

The word ‘lignin’ comes from the Latin “lignum” and means “wood”. In scientific literature lignin is often described as “the second most abundant polymer in the world” which is itself the most abundantly used statement in the 1000+ scientific articles on lignin published every year. As a biomass component, lignin has many special characteristics that keep plants stable and help them stay healthy:

1. Structural support
   It serves as a natural glue, maintaining the plants’ structural integrity and giving them resistance to biological and environmental damage. In addition to that it provides mechanical strength to resist wind, gravity, and other physical forces.
2. Antioxidative functions
   It helps protect cells from damage caused by free radicals.
3. Disease defense
   It is part of the plant’s defense system against pathogens and pests by forming physical barriers that prevent the spread of invaders within the plant tissues.
4. Stress protection
   Lignin helps protect plants against environmental stressors such as UV radiation, extreme temperatures, and dehydration.

Realizing that lignin has all these great characteristics makes it hard to believe that it is much less known than cellulose. However, for many decades the pulp and paper industry has only regarded it as a “by-product” which is an euphemism for simply burning it to supply energy and pulping reagents.

Approximately 50 million tons of lignin are produced in Europe every year. But only 40% of the generated lignin is needed to cover the internal energy demand for these biorefineries. That means a lot of lignin could be used for something else than energy production. So, why do we still waste lignin instead of using its functional properties?

The answer lies in the complex and always changing structure of the lignin molecule which makes standardized industrial processing extremely difficult.

The challenging structure of lignin

The structure of lignin is influenced by three different factors:

1. Its composition
2. Its origin
3. Its extraction process

Lignin itself is highly heterogenous due to its composition of different monomers, which make up one lignin polymer. These monomers can be composed in various ways. Meaning even if one took two samples of the same plant, the microscope would show two different compositions of lignin. With this in mind, this diverse structure makes it nearly impossible to use as a functional material in high-value applications.

Furthermore, lignin occurs in different types of wood. There are hardwood lignins, softwood lignins and herbaceous plants. The more rigid a plant is, the more lignin it contains. Moreover, each plant has a different lignin structure. Considering these different types, one can already grasp the complexity of lignin.

As a matter of fact, there is even one more source of heterogeneity: the extraction method. Lignin can be extracted in many different ways, e.g. depolymerization and modification of its molecular structure via chemical or enzymatical pathways being two of them. These different extraction processes make it still difficult to use lignin – because they increase heterogeneity even further.

Summing up it can be said that the refining methods, the different sources and the structural composition all are part of lignin’s heterogeneity and make it difficult for industrial processing. Some extraction methods use sulfates, agglomerations occur, and much energy is used to bring lignin in a size where one can work with it. Therefore, there needs to be an alternative that is eco-friendly, high performing and resulting in homogenous lignin particles which can easily be used in high-value applications.

Lignovations’ Colloidal Technology

Based on decades of knowledge generated by researchers and industry we have developed a process that yields lignin products that can be used broadly. Our refining technology amplifies the natural properties of the lignin while protecting our environment and our health. We manufacture tiny lignin particles in colloidal form (colloidal lignin particles or CLPs), which maximize performance and processability.

Our technology decreases lignin particles’ size purely with physical processes and no chemical modifications. These generated CLPs can be used in a range of application areas such as cosmetics, pharmaceuticals, food packaging, functional coatings, films, wood veneers, adsorbents, biomaterials, fertilizers, corrosion inhibitors, antifouling membranes and many more.

By downsizing lignin and reducing its heterogeneity, we can upcycle lignin that otherwise would go to waste into a multifunctional ingredient for a variety of applications. Learn more about colloidal lignin and its advantages for lignin valorization in our blog article on the importance of lignin particle size.

Explore lignin’s versatility with us

Over many years we have accumulated extensive know-how on the utilization of lignin and we are excited for all the applications that are still waiting to be discovered. Contact us if you are interested in developing the existing applications and discovering further application areas. We appreciate everyone who wants to join us on this journey.