Magnesium lignosulfonate (CAS 8061-54-9) is the magnesium salt of lignosulfonic acid: a water-soluble, anionic polymer made from lignin in magnesium-base sulfite pulping. This page covers its chemistry and the data that buyers use to identify a grade.
Chemical Identity
| Item | Value |
|---|---|
| Name | Magnesium lignosulfonate (magnesium lignosulphonate) |
| Synonym | Lignosulfonic acid, magnesium salt |
| CAS | 8061-54-9 |
| Nature | Mixture of polymer chains; no single molecular formula |
| Charge | Anionic (sulfonate and carboxyl groups) |
How It Is Made
Wood is cooked with magnesium bisulfite. The lignin is sulfonated and dissolves into the spent liquor, which is then purified, evaporated, chemically treated and dried, as the Grade One TDS describes.
Measured Data (Grade One)
| Parameter | Grade One (GAC-MgLS-1) |
|---|---|
| Appearance | Yellow-brown powder |
| pH | 4 – 7 |
| Dry matter | 95% min |
| Moisture | 5% max |
| Water-insoluble matter | 1.0% max |
| Total magnesium and calcium | 8% min |
| Lignosulphonate content | 55% min (dry basis) |
| Sulphate | 2% max |
| Total reducing matter | 7% min |
| Density | 0.55 g/cm³ |
Chemical Behaviour
- Dissolves readily in water to an anionic solution.
- Adsorbs on mineral and cement surfaces and disperses them.
- Forms a film on drying (binding).
- Can complex metal ions.
- Stable in closed containers; avoid strong oxidizers, strong acids and bases and excessive heat (SDS).
All Grades
| Grade (code) | Form | Lignosulphonate (dry basis) | pH | Other key values |
|---|---|---|---|---|
| Grade One (GAC-MgLS-1) | Yellow-brown powder | 55% min | 4 – 7 | Total Mg + Ca 8% min; insolubles 1.0% max; reducing matter 7% min |
| Grade Two (GAC-MgLS-2) | Powder | 50% min | around 10 | Total Mg + Ca 5% min; insolubles 1.5% max |
| Liquid (GAC-MgLS-L) | Liquid, about 45% solids | 50% min | — | Insolubles 1% max; reducing sugar about 7% |
| Feed Grade (GAC-MgLS-Feed) | Light to dark brown powder | 55% min | 4.5 – 6.5 | Pb 10, As 3, Cd 1 mg/kg max; Salmonella negative in 25 g |
More chemistry on lignosulfonate.com.
Magnesium, Calcium and Sodium Compared
| Property (Grade One) | Magnesium (GAC-MgLS-1) | Calcium (GAC-CaLS-1) | Sodium (GAC-NaLS-1) |
|---|---|---|---|
| CAS | 8061-54-9 | 8061-52-7 | 8061-51-6 |
| Lignosulphonate (dry basis) | 55% min | 55% min | 55% min |
| Ca + Mg | 8% min (total Mg + Ca) | 5 – 8% | 0.5% max |
| Water-insoluble matter | 1.0% max | 1.5% max | 1.5% max |
| pH | 4 – 7 | — | 7.0 – 9.5 (10% solution) |
| Moisture | 5% max | 5% max | 5% max |
Test Methods Used on the COA
| Property | Method |
|---|---|
| Lignosulphonate content | UV spectrophotometry |
| Dry matter / moisture | Oven drying |
| Water-insoluble matter | Filtration, gravimetric |
| pH | pH meter on a solution |
| Total Mg + Ca | Titration |
Frequently Asked Questions
What is the chemical name of magnesium lignosulfonate?
Lignosulfonic acid, magnesium salt; CAS 8061-54-9.
Does magnesium lignosulfonate have a molecular formula?
No single formula, because it is a mixture of polymer chains of different sizes.
What reacts with magnesium lignosulfonate?
The SDS advises keeping it away from strong oxidizers, strong acids and bases and excessive heat.
Is magnesium lignosulfonate soluble in water?
Yes, readily soluble or dispersible in water according to the SDS.
Is magnesium lignosulfonate the same as lignin?
No. It is lignin that has been sulfonated, which makes it water-soluble; native lignin is not.
