Magnesium lignosulfonate is a versatile, water-soluble anionic polyelectrolyte derived from the sulfite pulping process of wood in the paper industry. It is a byproduct of lignin, a complex polymer found in plant cell walls, modified through sulfonation to introduce sulfonic acid groups, enhancing its solubility and functionality. Typically appearing as a light yellow to brown powder, magnesium lignosulfonate is widely used in industries such as construction (concrete admixtures), agriculture (soil stabilization), animal feed (pellet binding), ceramics, dust control, and chemical processing (dispersants and chelating agents).
The following specifications are typical for magnesium lignosulfonate, though exact values may vary by manufacturer and application requirements. These are compiled from industry sources and general standards:
- Product Name: Magnesium Lignosulfonate (Magnesium Lignosulphonate)
- Chemical Formula: Variable, as it is a complex polymer (general representation: lignosulfonic acid, magnesium salt)
- CAS Number: 8061-54-9
- Appearance: Light yellow to brown powder or fine granular material
- Solubility: ≥98.5% soluble in water; insoluble in ethanol, acetone, benzene, and neutral solvents
- Lignosulfonate Content: 55–60% (dry basis, primary active component)
- Moisture Content: ≤7% (typically 3–7%, depending on drying process)
- pH Value: 4–6 (measured in a 5–10% aqueous solution at 25°C)
- Water-Insoluble Matter: ≤0.5–1% (indicating high purity for industrial use)
- Reducing Sugars: ≤5–7% (residual sugars from the pulping process)
- Calcium & Magnesium Content: 5–8% (magnesium as the primary cation, with trace calcium possible)
- Ash Content: ≤12% (non-combustible residue, indicating mineral content)
- Sulfate Content: ≤4–6% (as SO₄²⁻, from sulfonation process)
- Chloride Content: ≤0.5% (low chloride ensures compatibility with concrete and other sensitive applications)
- Molecular Weight: 1,000–140,000 Da (polydisperse, varying with processing conditions)
- Bulk Density: 0.3–0.5 g/cm³ (depending on particle size and packing)
- Particle Size: Typically 80–100 mesh (fine powder for better dissolution)
- Packaging: Available in 25 kg woven polypropylene bags, 550 kg jumbo bags, or customized bulk packaging
- Storage: Store in a cool, dry, well-ventilated area away from moisture and strong oxidants
- Shelf Life: Typically 24 months under proper storage conditions
Chemical and Physical Properties
- Chemical Nature: Magnesium lignosulfonate is an anionic polyelectrolyte with sulfonic acid groups (-SO₃⁻) attached to a lignin backbone, neutralized with magnesium ions. This structure imparts excellent water solubility and dispersant properties.
- Thermal Stability: Stable up to approximately 200°C, suitable for high-temperature industrial processes like ceramics or asphalt production.
- Hygroscopicity: Moderately hygroscopic; absorbs moisture if not stored properly, which may affect flowability.
- Environmental Profile: Biodegradable, non-toxic, and eco-friendly, making it suitable for applications like agriculture and animal feed.
Applications and Functional Benefits
Magnesium lignosulfonate’s unique properties make it valuable across multiple industries. Below is an expanded overview of its applications:
- Concrete Admixtures:
- Role: Acts as a water-reducing agent and superplasticizer in concrete formulations.
- Benefits: Reduces water content by 10–15%, improving workability, compressive strength, and durability of concrete. Enhances flowability without segregation.
- Usage: Typically dosed at 0.2–0.5% by weight of cement.
- Standards Compliance: Often meets ASTM C494 Type A (water-reducing) and Type F (high-range water-reducing) specifications.
- Dust Control:
- Role: Used as a dust suppressant on unpaved roads, mining sites, and construction areas.
- Benefits: Binds dust particles to surfaces, reducing airborne particulates and improving safety and visibility. Environmentally friendly compared to chloride-based suppressants.
- Application: Applied as a diluted aqueous solution via spraying equipment.
- Soil Stabilization and Agriculture:
- Role: Soil conditioner and stabilizer in erosion control and agricultural applications.
- Benefits: Improves soil structure, enhances water retention, and promotes nutrient availability. Used in reclamation projects for degraded soils.
- Additional Use: Acts as a dispersant in pesticide and fertilizer formulations, improving spray uniformity.
- Animal Feed:
- Role: Binder in pelleted feed production.
- Benefits: Increases pellet durability, reduces dustiness, and improves feed handling. Non-toxic and safe for livestock.
- Dosage: Typically 1–3% by weight in feed formulations.
- Ceramics and Refractories:
- Role: Binder and dispersant in ceramic slurries and refractory materials.
- Benefits: Reduces viscosity of slurries, improves green strength of ceramic bodies, and enhances moldability.
- Chemical and Industrial Applications:
- Dispersant: Used in dyes, pigments, and pesticide formulations to prevent agglomeration and improve stability.
- Chelating Agent: Binds metal ions in wastewater treatment, aiding in heavy metal removal.
- Oil Drilling: Component in drilling muds to control viscosity and stabilize emulsions.
- Carbon Black and Asphalt: Improves dispersion and binding in carbon black production and asphalt emulsions.
Quality and Testing Standards
- Purity Testing: Determined via gravimetric analysis for lignosulfonate content and titration for magnesium content.
- Solubility Testing: Ensures ≥98.5% dissolution in water, critical for applications requiring aqueous solutions.
- pH and Impurity Checks: Conducted to confirm compliance with pH range and low levels of water-insoluble matter or chlorides.
- Performance Testing: For concrete admixtures, tested for water reduction, setting time, and compressive strength per ASTM or EN standards.
Safety and Handling
- Safety: Non-toxic, non-hazardous, and non-corrosive. No special precautions required beyond standard industrial hygiene practices.
- Handling: Wear dust masks to avoid inhalation during handling of powder. Use gloves to prevent skin contact in sensitive individuals.
- Environmental: Biodegradable and considered environmentally safe. Avoid release into water bodies in large quantities to prevent oxygen depletion during degradation.
Supplier and Customization Notes
- Suppliers: Companies like Green Agrochem offer magnesium lignosulfonate with tailored specifications for specific industries. For example, Green Agrochem emphasizes low moisture and high lignosulfonate content for concrete applications.
- Customization: Specifications can be adjusted (e.g., pH, lignosulfonate content, or particle size) based on customer needs. Contact suppliers for custom formulations or technical data sheets.
- Availability: Widely available globally, with major production in North America, Europe, and Asia due to the prevalence of sulfite pulping.
Additional Considerations
- Comparison with Other Lignosulfonates: Magnesium lignosulfonate is similar to calcium or sodium lignosulfonate but offers specific advantages, such as better solubility in certain pH ranges and compatibility with magnesium-based systems. It is often preferred in applications requiring low sodium content (e.g., animal feed or specific concrete mixes).
- Regulatory Compliance: Generally recognized as safe (GRAS) for animal feed in many regions. For construction, ensure compliance with local standards (e.g., ASTM, EN, or IS).
- Sustainability: As a byproduct of the paper industry, magnesium lignosulfonate supports circular economy principles by repurposing waste lignin.