Sodium Metabisulfite (SMBS), represented by the chemical formula Na2S2O5 (CAS No.: 7681-57-4, EC No.: 231-673-0), is an inorganic, white to slightly yellowish crystalline powder with a faint odor of sulfur dioxide (SO2). Functioning as a potent reducing agent, antioxidant, and preservative, SMBS dissolves readily in water to form sodium bisulfite (NaHSO3), generating a mildly acidic solution with strong reducing activity.
In the global chemical marketplace, Sodium Metabisulfite is a critical raw material across diverse sectors including municipal and industrial water treatment, mining and mineral processing, food and beverage preservation, textiles, and chemical manufacturing. As supply chains prioritize purity consistency, environmental compliance, and cost optimization, sourcing high-grade SMBS from established manufacturers has become an essential strategy for industrial procurement teams.
Grades, Technical Specifications & Quality Assurance
Selecting the appropriate grade of Sodium Metabisulfite is vital to prevent process contamination, ensure regulatory compliance, and optimize operational efficiency. Hoochemtec manufactures and exports two primary market grades: Food Grade (E223/FCC) and Technical Grade.
Key Specification Comparison (CoA Standard Parameters)
| Parameter | Food Grade (E223 / FCC) | Technical / Industrial Grade |
|---|---|---|
| Main Purity (Na2S2O5) | ≥ 97.0% | ≥ 96.5% |
| Sulfur Dioxide (SO2) Content | ≥ 65.3% | ≥ 65.0% |
| pH Value (5% aqueous soln) | 4.0 – 4.8 | 4.0 – 4.8 |
| Iron (Fe) | ≤ 5 ppm (0.0005%) | ≤ 15 ppm (0.0015%) |
| Heavy Metals (as Pb) | ≤ 5 ppm | ≤ 20 ppm |
| Arsenic (As) | ≤ 1 ppm | ≤ 5 ppm |
| Clarity / Appearance | Clear, colorless in water | Slightly off-white to clear |
| Certifications Available | ISO 22000, HALAL, KOSHER, FCC | ISO 9001, REACH, SGS Inspection |
Quality Assurance Focus: Low-Iron Control for Membrane Safety
In high-tech industrial reverse osmosis (RO) systems, trace iron (Fe) contamination can lead to severe membrane fouling and catalytic degradation. Hoochemtec enforces strict micro-filtration during crystallization to guarantee iron levels consistently remain below 5–10 ppm, protecting sensitive membrane surfaces.
Key Industrial Applications
1. Water Treatment & RO Membrane Dechlorination
In industrial effluent treatment and seawater reverse osmosis (SWRO) desalination, free chlorine and ozone are used as biocides to destroy microorganisms. However, oxidizers degrade delicate polyamide RO membranes. Sodium Metabisulfite serves as the industry-standard chemical dechlorinating agent, reacting rapidly with hypochlorous acid (HOCl) according to the stoichiometric equation:
Na2S2O5 + 2 HOCl + H2O → Na2SO4 + H2SO4 + 2 HCl
Approximately 1.8 to 3.0 ppm of SMBS is typically dosed per 1.0 ppm of free residual chlorine to ensure complete dechlorination, prevent biofouling, and preserve membrane integrity.
2. Gold Mining & Cyanide Detoxification
In gold and silver hydrometallurgy, SMBS plays a pivotal role in the widely adopted INCO SO2/Air Cyanide Detoxification Process. Free and weak-acid-dissociable (WAD) cyanides present in tailing slurries are oxidized to less toxic cyanates (CNO–) in the presence of copper catalysts:
CN– + SO2 + O2 + H2O → CNO– + H2SO4
Mining operators prefer Hoochemtec’s heavy-duty bulk bags due to consistent particle size, low dusting, and rapid dissolution rates under high-throughput mine site conditions.
3. Food & Beverage Processing (Preservative E223)
As a regulated food additive (E223), SMBS acts as an antimicrobial, antioxidant, and anti-browning agent in dried fruits, potato products, wines, and seafood. It prevents enzymatic and non-enzymatic (Maillard) browning while extending shelf life by inhibiting bacterial and fungal growth.
4. Chemical Synthesis, Textiles & Paper Industry
SMBS serves as a reducing agent in pharmaceutical synthesis, a bleaching agent for wool and jute, an antichlor in paper mill bleaching operations, and a sulfonation agent in surfactant manufacturing.
Packaging, Logistics & Safe Handling
Standard Packaging Configurations
- 25 kg PP/PE Bags: Multi-layer polypropylene woven bags with an internal polyethylene liner to prevent moisture ingress and oxidation.
- 1000 kg / 1100 kg Jumbo Bags (FIBC): Heavy-duty bags designed for automated discharge in water treatment plants and mining operations.
- Custom Private Labeling: OEM bag design and palletized stretch-wrap solutions tailored for regional distributors.
Logistics & Regulatory Compliance
Depending on regional customs standards and physical state specifications, Sodium Metabisulfite is classified as either a non-hazardous solid or under UN 2693 / Class 8 (Corrosive Solids, Acidic, Inorganic). Hoochemtec provides fully compliant SDS (Safety Data Sheets) in multiple languages, fully meeting GHS, REACH, and IMDG guidelines.
Storage & Stability Recommendations
SMBS gradually decomposes upon exposure to moisture and atmospheric air, releasing toxic sulfur dioxide (SO2) gas and converting into sodium bisulfate. It must be stored in a cool, dry, well-ventilated warehouse away from strong acids, oxidizing agents, and direct heat sources. When kept in sealed original packaging under ideal storage conditions, the typical shelf life is 24 months.
Pricing Drivers & B2B Sourcing Strategies
Understanding cost dynamics allows procurement teams to secure favorable contract terms. Primary price determinants include:
- Upstream Raw Material Costs: Soda Ash (Na2CO3) and Sulfur (S) pricing fluctuations directly dictate base manufacturing costs.
- Grade & Purity Level: Food Grade SMBS commands a premium over technical grade due to refined crystallization, stringent heavy-metal controls, and food safety certifications.
- Freight & Logistics Dynamics: Global container ocean freight rates and regional port fees heavily impact CIF landed prices.
Why Partner with Hoochemtec?
Hoochemtec is a global chemical exporter dedicated to providing dependable supply chain solutions and technical excellence to industrial partners worldwide.
- Consistent Quality Control: Every production batch undergoes comprehensive laboratory analysis with guaranteed Certificate of Analysis (CoA) traceability.
- Flexible Lead Times: Large-scale warehouse inventory ensures standard orders ship within 7–14 days.
- Comprehensive Compliance: Full international regulatory support, including ISO, REACH, HALAL, KOSHER, and third-party inspection (SGS/BV) upon request.
- Technical Support & Free Samples: Our chemical engineers offer dosage recommendations, solubility consultation, and complimentary sample testing for pilot evaluations.
Frequently Asked Questions (FAQ)
Q1: What is the difference between Sodium Metabisulfite and Sodium Bisulfite?
Sodium Metabisulfite (Na2S2O5) is the anhydrous, solid powder form of Sodium Bisulfite (NaHSO3). When dissolved in water, SMBS hydrolyzes instantly into sodium bisulfite ions. SMBS is preferred for international shipping due to higher active concentration and reduced transportation costs per unit of active SO2.
Q2: How does Sodium Metabisulfite protect Reverse Osmosis (RO) membranes?
SMBS acts as a rapid scavenger of free active chlorine (hypochlorous acid), converting oxidizers into harmless chloride ions. This neutralizes oxidative potential before water passes through sensitive thin-film composite polyamide membranes, preventing permanent structural damage.
Q3: What is the shelf life of Hoochemtec Sodium Metabisulfite?
When stored in original, unopened moisture-proof packaging in a cool, dry warehouse environment, Hoochemtec SMBS maintains a guaranteed shelf life of 24 months from the date of manufacture.
Request a Bulk Quote or Technical Sample Today
Looking for a reliable, high-purity Sodium Metabisulfite manufacturer for your water treatment plant, mine site, or chemical distribution network? Contact Hoochemtec’s technical export team today for real-time pricing, Certificates of Analysis (CoA), and complimentary testing samples.
Email: sales@hoochemtec.com | Web: www.hoochemtec.com
