Lignin - Economic Significance

Economic Significance

Highly lignified wood is durable and therefore a good raw material for many applications. It is also an excellent fuel, since lignin yields more energy when burned than cellulose. Mechanical, or high-yield pulp used to make newsprint contains most of the lignin originally present in the wood. This lignin is responsible for newsprint's yellowing with age. Lignin must be removed from the pulp before high-quality bleached paper can be manufactured.

In sulfite pulping, lignin is removed from wood pulp as sulfonates. These lignosulfonates have several uses:

• Dispersants in high performance cement applications, water treatment formulations and textile dyes

• Additives in specialty oil field applications and agricultural chemicals

• Raw materials for several chemicals, such as vanillin, DMSO, ethanol, xylitol sugar, and humic acid

• Environmentally sustainable dust suppression agent for roads

The first investigations into commercial use of lignin were reported by Marathon Corporation in Rothschild, Wisconsin (USA), starting in 1927. The first class of products that showed promise were leather tanning agents. The lignin chemical business of Marathon was operated for many years as Marathon Chemicals. It is now known as LignoTech USA, Inc., and is owned by the Norwegian company Borregaard.

Lignin removed via the kraft process (sulfate pulping) is usually burned for its fuel value, providing energy to run the mill and its associated processes.

More recently, lignin extracted from shrubby willow has been successfully used to produce expanded polyurethane foam.

In 1998, a German company, Tecnaro, developed a process for turning lignin into a substance, called Arboform, which behaves identically to plastic for injection molding. Therefore, it can be used in place of plastic for several applications. When the item is discarded, it can be burned just like wood.

In 2012, it was shown carbon fiber can be produced from lignin instead of from fossil oil.