Lignosulfonate binders, emulsifiers and dispersants
The only lignin products obtained from a pulping process that have found a vast range of applications up to now are lignosulfonates. These are non-hazardous materials with excellent properties that are used as binders, emulsifiers and dispersants for a great variety of materials.
As inexpensive components in binders, lignosulfonates are commonly used for commodities like coal briquettes, ceramics,briquetting of mineral dust, and the production of plywood or particle boards. Their ability to retain moisture and suppress dust makes them a useful tool for construction works, gravel roads, airports and sports facilities.
As an anti-settling agent that also prevents lumping, lignosulfonates are used in concrete mixtures, ceramics, gypsumboard production and for leather tanning. Lignosulfonates provide flowability and plasticity to cement. This is a replacement for more expensive materials that provide setretardation such as superplasticisers, gluconates and gluconic acid. Wet-process Portland cement mills utilise lignosulfonates to increase the solids content of raw slurries.
Lignin-based concrete additives are in demand and can be worth as much as $1.05–$1.32/L as an aqueous solution (Holladay et al., 2007). Sulfur-free lignin such as soda lignin has also been shown to improve flowability of mortar (Nadif et al., 2002).
Lignosulfonates can also stabilise emulsions of immiscible fluids like asphalt emulsions, pesticide preparations, pigments and dyes. Due to their low toxicity, they can be used as binders in animal feed and thereby improve the feed properties of pellets.
In addition, lignosulfonates show the ability to keep micronutrients in solution which is useful for micronutrient transport or as a cleaning and decontaminating agent in water and soils (Nadif et al., 2002; Calvo-Flores and Dobado, 2010)