Sodium Metabisulphite (SMBS) is a white crystalline powder widely used as a reducing agent, bleaching agent, antioxidant, and preservative in multiple industrial processes.
Helps convert dyes to a soluble leuco form
Improves dye uptake and levelness
Prevents oxidation during dyeing operations
Used to correct dyeing faults
Removes unfixed dye on fabric surface
Effective in reprocessing dyed goods
Safe bleaching of wool, silk, leather & delicate fibers
Prevents excessive fiber damage compared to chlorine bleach
Removes residual chlorine from hypochlorite bleaching
→ Prevents fiber weakening, yellowing & brittleness
Removes dyes and pigments from wastewater
Acts as a reducing chemical to lower COD/Color
Protects certain dye formulations from oxidation
Extends bath life and maintains color consistency
| Application | Dosage |
|---|---|
| Vat/sulphur dyeing | 1–10 g/L |
| Anti-chlor treatment | 0.5–2 g/L |
| Stripping | 2–10 g/L |
| Effluent decolorization | As per COD/Color load |
Note: Exact dosing depends on fiber type, dye class & equipment.
Strong reducing ability
Quick reaction and high effectiveness
Protects fabric quality and dye fastness
Cost-effective alternative to other reducers
Preservative and antioxidant in food production
Prevents oxidation & microbial spoilage
Common in wines, juices, dried fruits, starch
Dechlorination of municipal & industrial water
Heavy metal precipitant (especially Cr⁶⁺ reduction)
Bleaching stabilizer
Controls oxidation of lignin
Leather Industry
Aids in leather deliming and pickling
Prevents grain damage & discoloration
| Function | Description | Benefits |
|---|---|---|
| Deliming Agent | Helps remove liming chemicals from hides | Reduces damage, improves softness |
| Pickling & pH Control | Maintains required acidity during tanning | Enhances chrome uptake efficiency |
| Bleaching of Dark Grains | Reduces natural pigment in hides | Produces cleaner and brighter leather |
| Preservative & Antioxidant | Prevents oxidation of leather chemicals | Improves chemical stability |
| Chromium (VI) Reduction | Converts toxic Cr⁶⁺ → safe Cr³⁺ in wastewater | Essential for meeting environmental standards |
Used widely in chrome tanning operations
Strong reducing capability
Cost-effective and fast-reacting
Protects fabric & hide quality
Serves both process enhancement and environmental control
Intermediate for sodium dithionite production
Used in pharmaceuticals, photography chemicals
Oxygen scavenger to prevent pipeline corrosion
Sodium Metabisulphite is a widely used reducing agent in industrial and municipal wastewater treatment. Its primary function is to neutralize oxidizing agents, remove toxic metals, and reduce colored organic pollutants for safer discharge.
Used to remove excess free and combined chlorine after disinfection (e.g., NaOCl or Cl₂ bleaching).
Chemical Reaction
Cl₂ + Na₂S₂O₅ + H₂O → 2HCl + Na₂SO₄
Prevents toxic chlorine discharge to the environment
Protects downstream biological treatment systems
Ensures compliance with effluent chlorine limits
Applied in:
Textile wastewater after bleaching
Drinking water plants
Industrial process water
Particularly effective in converting Hexavalent Chromium (Cr⁶⁺) to Trivalent Chromium (Cr³⁺) — the safer and precipitable form.
Reaction:
Cr⁶⁺ → Cr³⁺ (reduced) → Cr(OH)₃ (precipitated)
✔ Essential for leather tannery effluents, electroplating wastewater
✔ Helps meet strict global environmental standards
Acts as a strong reducing agent to break down:
Reactive dye chromophores
Sulfur & vat dye residues
Oxidized organic contaminants
Result: Lower color units, improved water quality clarity
Used commonly in textile & paper mill wastewater
Works as anti-microbial under low pH conditions
Enhances hygienic control in water systems
Not a replacement for primary disinfection but supports bio-control.
Removes dissolved oxygen in boiler feedwater systems to prevent corrosion.
O₂ + Na₂S₂O₅ → Na₂SO₄
Used in:
Boilers
Pipelines
Oil & gas injection water
| Purpose | Dosage (approx.) |
|---|---|
| Dechlorination | 1.0–4.0 mg SMBS per 1 mg/L of chlorine |
| Heavy metal reduction | Based on metal load & pH control |
| Dye wastewater | Determined by color & COD levels |
| Boiler water | 10–50 mg/L depending on O₂ levels |
Exact dosage must be optimized via jar tests and process parameters.
Strong reducing efficiency
Rapid reaction kinetics
Cost-effective
Safe handling & storage vs. gaseous sulfur dioxide
Wide compatibility with treatment systems
Avoid exposure to moisture; releases SO₂ gas
Use ventilation and protective equipment
Store in cool, dry, sealed containers
Keep away from acids
NGHI SON CHEMICALS IMPORT EXPORT COMPANY LIMITED
Head office:
P7-38.OT09 ("Officetel") Vinhomes Central Park, 720A Dien Bien Phu Street, Thanh My Tay Ward, Ho chi minh city, Vietnam 70000
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Tel: +84-28-36208490
Fax : +84-28-36208492
Website: https://www.nghisonchemical.com
Email : Nghisonchem@nghisonchemical.com
Nscchem@nghisonchemical.com
Nghisonchem@gmail.com
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