Lignosulphonate is an organic substance binding the cells, fibres and vessels which constitute wood and the lignified elements of plants, as in straw. After cellulose, it is the most abundant renewable carbon source on Earth. Between 40 and 50 million tons per annum are produced worldwide as a mostly non commercialized waste product.
It is not possible to define the precise structure of lignosulphonate as a chemical molecule. All lignosulphonates show a certain variation in their chemical composition. However the definition common to all is a dendritic network polymer of phenyl propene basic units.
There are two principal categories of lignosulphonate: those which are sulphur bearing and those which are sulphur-free. It is the sulphur bearing lignosulphonates which have to date been commercialized. These include lignosulphonates (world annual production of 500,000 tons) and Kraft lignosulphonates (under 100,000 tons p.a.). Due to the lack of suitable industrial processes, the sulphur-free lignosulphonates are as yet non-commercialized.
As a natural and renewable raw material, obtainable at an affordable cost, lignosulphonate’s substitution potential extends to any products currently sourced from petrochemical substances. The areas in which lignosulphonate is applicable include:
1) Multy-polarity related products
Lignosulphonate contains both hydrophilic and hydrophobic groups. Specific treatments can strengthen either characteristic for particular applications as in emulsions and dispersants.
2) Materials
Binders, thermoset, etc. Lignosulphonate is a natural branched and crosslinked network polymer which lends itself to use in materials.
3) Agriculture
Lignosulphonate and lignosulphonate derived products play an important role in the formation of soils and in plant and animal nutrition.
4) High purity / value applications
High purity support materials or active substances: lignosulphonate can be used as support materials for food and cosmetic applications comprising gels or emulsifiers; specially prepared lignosulphonates are suitable as an active substance with anti-oxidant, anti-bacterial and anti-viral properties. These qualities have already been explored and could play an important role in the future.