Sodium lignosulphonate (also spelled sodium lignosulfonate) is a water-soluble, anionic polymer made from lignin, the natural binder in wood. It is recovered from the sulfite pulping of wood and is used mainly as a dispersant, concrete water reducer and binder. Our product range is on the sodium lignosulfonate product page.
Key Facts
| Item | Detail |
|---|---|
| Other names | Sodium lignosulfonate, sodium lignin sulfonate, lignosulfonic acid sodium salt (sometimes misspelled “sodium lignosulfate”) |
| CAS number | 8061-51-6 |
| Type | Anionic, water-soluble polymer; a mixture of chain sizes, not a single molecule |
| Source | Spent liquor from sulfite pulping of wood |
| Appearance | Yellow-brown to brown powder; liquid grades are dark brown to black |
| Molecular weight | Typically about 10,000 – 50,000 g/mol for lignosulfonates used as dispersants (review data) |
| Main functions | Dispersant, water reducer (plasticizer), binder, dust suppressant |
How It Is Made
In sulfite pulping, wood chips are cooked with a sulfite or bisulfite liquor. The lignin is sulfonated and dissolves, while the cellulose fibre goes to papermaking. The lignosulfonate is recovered from the spent liquor, purified and dried. In the sodium-base process it forms directly as the sodium salt; otherwise it can be converted by neutralising lignosulfonic acid with sodium hydroxide or sodium carbonate. Full steps: how sodium lignosulfonate is produced.
Structure
It is a branched aromatic polymer built from phenylpropane units. Sulfonate groups (attached during pulping) and carboxyl groups carry the negative charge, and phenolic groups add reactivity. The charge makes it dissolve in water and adsorb on particles. Because chain sizes vary, no single formula describes it: sodium lignosulfonate structure and sodium lignosulfonate formula.
Main Uses
- Concrete and cement: normal-range water reducer and grinding aid; strength effects depend on the mix and dosage.
- Dispersant: for pesticide formulations, dyes, carbon black, and clay or mineral slurries.
- Binder: for ceramic bodies, iron ore fines, coal, briquettes and feed pellets.
- Dust control: on unpaved roads and in dusty industrial areas.
- Oil drilling: thinner for water-based drilling muds.
- Leather: retanning and dye-leveling auxiliary, used alongside the main tanning agents.
- Lead-acid batteries: organic expander in negative plates.
Grade guidance and application details are on LigninCorp’s sodium lignosulfonate page; properties are summarised on sodium lignosulfonate properties.
How Grades Differ
| Grade | Lignosulphonate content | Reducing sugar | Insolubles | Typical use |
|---|---|---|---|---|
| Grade One | 55% min (dry basis) | 7% max | 1.5% max | General purpose: concrete, ceramics, binders, dispersant |
| Construction Grade | 65% min | 7% max | 1% max | Concrete water reducer |
| Light Color, Lower Sugar | Total lignin 50% min | 3.5% max | Not listed | Light-coloured admixtures, selected feed uses |
| Super Grade | 95% min (dry basis) | Not listed | 0.5% max | High-purity dispersant and emulsifier |
| Liquid Grade | 50% min | Around 7% | 1.0% max | Direct dosing from tanks; 45% min solids |
Safety and environmental questions should be answered from the product SDS rather than from its natural origin: environmental and safety considerations.
Frequently Asked Questions
What is sodium lignosulphonate?
A water-soluble, anionic polymer made from wood lignin during sulfite pulping. It is used as a dispersant, concrete water reducer and binder. CAS 8061-51-6.
Is it lignosulphonate or lignosulfonate?
Both spellings are correct. “Lignosulphonate” is British spelling and “lignosulfonate” is American; they name the same material.
Is sodium lignosulphonate the same as lignin?
It is lignin that has been sulfonated during pulping. The sulfonate groups make it water-soluble, which ordinary lignin is not.
What is sodium lignosulphonate used for?
Mainly as a concrete water reducer, a dispersant for pesticides, dyes and slurries, a binder for ceramics, ore fines and pellets, and a dust suppressant.
