SODIUM LIGNOSULFONATE — DETAILED OVERVIEW
1. General Introduction
Sodium lignosulfonate is a derivative of lignin—a natural polymer found in the cell walls of plants, especially wood. It is primarily produced as a byproduct of the sulfite pulping process in the paper industry, where lignin is sulfonated and dissolved, then neutralized with sodium to form the sodium salt of lignosulfonic acid.
2. Chemical Information
| Property | Value |
|---|---|
| Chemical Name: | Sodium lignosulfonate |
| Alternative Name: | Lignosulfonic acid, sodium salt |
| Empirical Formula (approximate): | C20H24Na2O10S2 (varies depending on source) |
| Molecular Weight (average): | ≈ 534.5 g/mol |
| Structure: | Irregular polymer containing phenylpropane units with sulfonate (-SO₃⁻) and hydroxyl (-OH) groups |
| CAS Number: | 8061-51-6 |
⚠️ Note: Sodium lignosulfonate is a natural polymer, so its exact molecular weight and composition can vary depending on raw material and processing method. The value 534.5 g/mol is a representative average.
3. Physical Properties
| Property | Description |
|---|---|
| Appearance: | Light brown to dark brown powder, or viscous dark liquid |
| Solubility: | Completely soluble in water |
| pH (10% solution): | Approximately 4 – 7 |
| Moisture Content (in powder form): | Less than 10% |
| Ash Content (as Na₂O): | Around 20 – 30% |
| Density (50% solution): | ~1.3 g/cm³ |
4. Chemical Characteristics
- Functions as an anionic polyelectrolyte (negatively charged macromolecule)
- Capable of chelating metal ions
- Stable in alkaline solutions, moderately stable in weak acids
- Exhibits dispersing, binding, and emulsifying properties
- Acts as a weak surface-active agent
5. Industrial Applications
1. Construction (Concrete Admixtures):
- Used as a water reducer, improving workability and reducing water/cement ratio
- Enhances strength, reduces segregation, and improves surface finish
2. Ceramics Industry:
- Works as a dispersing agent in ceramic slips, reducing viscosity and improving moldability
3. Agriculture:
- Acts as a dispersant for pesticides, herbicides, and fertilizers
- Improves absorption and distribution of active ingredients in soil
4. Animal Feed Industry:
- Used as a binder for pellet formation
- Enhances durability of feed pellets, reduces dust
5. Oil Drilling:
- Serves as a mud thinner and stabilizer in drilling fluids
- Helps control fluid rheology and sediment suspension
6. Dust Control & Soil Stabilization:
- Sprayed onto roads or soil surfaces to reduce dust and prevent erosion
- Improves soil structure and minimizes runoff
6. Key Advantages
- Natural origin, biodegradable, and eco-friendly
- Low cost, widely available, and easy to handle
- Highly versatile, applicable in numerous industries
- Can partially replace more expensive synthetic dispersants (e.g., naphthalene or melamine sulfonates)
7. Safety Information
- Non-toxic, but prolonged direct contact or inhalation of dust should be avoided
- Use personal protection (mask, gloves) when handling in powder form
- Store in a dry, cool, well-ventilated area
- Refer to MSDS (Material Safety Data Sheet) for detailed safety handling procedures
8. Packaging and Storage
| Aspect | Detail |
|---|---|
| Packaging: | 25kg kraft paper bags, or jumbo bags (500–1000kg) |
| Storage: | Store in dry, cool, and covered areas, away from moisture |
| Shelf Life: | 12 to 24 months depending on storage conditions |