Biorefineries using wood for production of specialty cellulose fibers, lignosulfonates, vanillin, bioethanol and biogas – the Borregaard Sarpsborg example - Biomass as Energy Source: Resources, Systems and Applications - page 144

Figure 8.4. Structural representation of spruce lignosulfonate.
absolute rectified 99.5%). All grades are certified as kosher/pareve and are utilized in a wide
variety of applications, including biofuels, paints, solvents and pharmaceuticals.
8.2.4 Biomaterials, lignosulfonates
After fermentation and distillation, the remaining cooking liquor constitutes the raw material for
production of different lignin chemicals. At this point, the main components in the liquor are
sulfonated lignins, i.e. lignosulfonates, which are produced in the pulping process by hydrolysis
and sulfonation of the wood lignin. Due to the introduction of the highly hydrophilic, charged
sulfonate groups, the lignin is solubilized into the cooking liquor.
Lignosulfonates are highly complex aromatic polymers with multiple functionalities, including
phenolic and aliphatic hydroxyl, methoxyl, carboxyl and sulfonate groups (Fig. 8.4).When leaving
the fermentation plant, the cooking liquor is still a complex mixture, containing lignosulfonates
of different molecular weights, but also certain amounts of residual (C5) sugar components,
inorganic salts and insolubles.
In the lignin modification plant, this raw material is processed further by fractionation, purifi-
cation and chemical modification (e.g. oxidation and desulfonation) depending on the end use of
the product.
Due to their multifunctional nature, lignosulfonates have both dispersing, complexing and
binding properties, making them useful in a wide variety of applications. Looking into the history
of lignosulfonates, many current applications were also known 50 years ago. However, changes in
the customers' technologies, introduction of new technologies, competition from other products
etc. have changed the picture, and improvements and new lignosulfonate products have been
the result of the company's ongoing R&D efforts. The interest for lignosulfonate products is also
increasing since the products are produced from renewable resources, are environmentally friendly
and sustainable. Today the most important applications include plasticizers in concrete, binder
in animal feed pellets, extender in batteries, corrosion inhibitors in organic acids, dispersant in