When specifying sodium sulfite bulk density, industrial buyers touch on far more than a simple physical constant. The bulk density of sodium sulfite (Na₂SO₃) directly influences packaging design, freight costs, silo sizing, dosing accuracy, and even the price you negotiate. For procurement managers at power plants, pulp mills, or textile finishing operations, overlooking this parameter can lead to hidden costs and operational inefficiencies. In this guide, we unpack what sodium sulfite bulk density means, how it varies between anhydrous and heptahydrate forms, and why it deserves a prime spot on your technical specification sheet.
Sodium sulfite bulk density refers to the mass per unit volume of the material in its freely settled state, expressed in kilograms per cubic meter (kg/m³) or grams per cubic centimeter (g/cm³). It accounts for the particle size distribution, shape, moisture content, and degree of compaction. Unlike true density, which measures only the solid matter, bulk density includes the interstitial air spaces between granules. For an industrial chemical like sodium sulfite, typical loose bulk densities range from 800 to 1,050 kg/m³ for the anhydrous grade, while the heptahydrate form (Na₂SO₃·7H₂O) often falls between 1,200 and 1,400 kg/m³ due to its crystalline water content. These values shift when the powder is tapped or vibrated—a phenomenon buyers must consider when designing silos or specifying big-bag dimensions.
A buyer who ignores bulk density risks paying for air. Sodium sulfite is sold by weight, but it is shipped and stored by volume. A lower bulk density means fewer kilograms fit into a 25 kg bag, 1-tonne FIBC, or bulk tanker—driving up packaging material costs, warehouse footprint, and freight charges per effective tonne. Conversely, a higher bulk density product may require less storage space and allow more flexible packaging, but could pose challenges in pneumatic conveying systems if it compacts easily. By understanding sodium sulfite bulk density, procurement teams can:
Leading suppliers like Weifang Hailei Fine Chemical Co., Ltd. provide bulk density data as part of the certificate of analysis, enabling data-driven purchasing decisions.
Sodium sulfite is commercially available as anhydrous (Na₂SO₃, 96–98% purity) and heptahydrate (Na₂SO₃·7H₂O). The heptahydrate contains approximately 50% water by weight, forming larger, denser crystals. Its bulk density is therefore significantly higher—often around 1,300 kg/m³ compared to the anhydrous grade’s 900 kg/m³. Buyers using sodium sulfite as an oxygen scavenger in boiler water systems typically prefer anhydrous for its higher active content, but they must account for the lower bulk density when retrofitting storage from a previous heptahydrate source.
The production process (crystallization, drying, milling) determines particle size and shape. Irregular flakes, fine powders, or compacted granules each pack differently. A fine powder may have a lower aerated bulk density but can compact heavily under vibration, creating a wide gap between “loose” and “tapped” densities. For consistent dosing in water treatment or textile bleaching neutralizers, buyers should request both loose and tapped bulk density values from the supplier.
Anhydrous sodium sulfite is hygroscopic and may absorb moisture during transit or storage, leading to caking and a measurable increase in bulk density. Tight moisture specifications (typically ≤0.5% for anhydrous) help maintain predictable material flow properties. Suppliers like Hailei Chemical package the product in moisture-resistant PE-lined bags and advise on proper storage conditions to preserve the original bulk density.
To appreciate the practical impact, consider a 20-foot shipping container. A container with a 25‑tonne payload could hold approximately 27.8 m³ of anhydrous sodium sulfite (assuming 900 kg/m³), but only 19.2 m³ of heptahydrate (at 1,300 kg/m³). The heptahydrate uses about 30% less volume for the same weight—potentially lowering freight costs if volume is the limiting factor. However, since the heptahydrate delivers only half the active Na₂SO₃, the landed cost per kilogram of effective chemical often favors anhydrous. This trade-off is central to sodium sulfite price negotiations. Speaking of which…
When evaluating sodium sulfite price, buyers typically focus on EXW, FOB, or CIF rates per metric tonne. Yet the true cost per functional unit depends on both purity and how much of the product actually arrives in usable form. Bulk density ties into this equation in two ways: first, through freight economics—lower bulk density means more pallets or containers to ship the same net weight; second, through processing losses if poor flowability or caking requires extra handling. A supplier offering a slightly higher unit price but a consistent, high bulk density with free-flowing particles can reduce total landed cost. Smart procurement teams therefore request bulk density specifications alongside chemical purity, heavy metals content, and solubility profiles. For transparent pricing and bulk density data, visit our sodium sulfite product page.
In the world of sodium-based chemicals, confusion is common. A recurring query is “what is sodium sulfate formula” and how it differs from sulfite. Sodium sulfate bears the formula Na₂SO₄ — a fully oxidized, stable salt commonly used in detergents and glassmaking. Sodium sulfite (Na₂SO₃), on the other hand, is a reduced form with strong antioxidant properties. The single oxygen atom difference changes everything: sulfite is a powerful dechlorinating agent and oxygen scavenger; sulfate is practically inert. Another frequent search is “what is sodium sulfide used for”. Sodium sulfide (Na₂S) is a tanning and dehairing agent in leather processing—distinct from sodium sulfite, which is also used in leather preparation but as a reducer for hair-saving methods and pH adjustment. Knowing these applications helps buyers avoid costly misorders.
An even simpler question some newcomers ask: “is salt a sulfite?” No, common table salt is sodium chloride (NaCl) and contains no sulfite group (SO₃²⁻). Sulfites are a class of sulfur‑oxygen compounds used as preservatives and reducing agents. While sodium sulfite is a salt in the chemical sense (a product of acid‑base neutralization), it shares nothing with culinary salt. This distinction matters for safety data sheets and regulatory compliance when handling industrial chemicals.
Reputable suppliers define sodium sulfite bulk density according to recognized methods such as ASTM D7481 (loose bulk density) or ISO 3923. For procurement contracts, a typical specification might read:
These ranges reflect real-world production from a reliable manufacturer like Hailei Chemical. Buyers should align their silo and feeder designs with the supplier’s typical values and request batch-specific COAs for sensitive applications. In boiler water treatment, where feed rates are precisely controlled, even a 5% deviation in bulk density can alter the mass flow from volumetric dosing systems, leading to under‑ or over‑dosing and potential corrosion or deposit issues.
For power plant chemical buyers, sodium sulfite as an oxygen scavenger must be fed consistently into high‑pressure boiler systems. A free‑flowing powder with a stable bulk density ensures volumetric feeders deliver the correct mass per stroke. If the bulk density drops because of an ultra‑fine grind, the same volume contains less active chemical, risking dissolved oxygen breakthrough. Conversely, a densified granule that packs too tightly may cause arching in the feeder hopper. Hailei Chemical produces an anhydrous sodium sulfite with carefully controlled granulation, striking a balance between dissolution rate and material handling—ideal for both batching and continuous treatment.
In pulp and paper mills, sodium sulfite is used in sulfite pulping and as a dechlorination agent. Bulk density here influences how quickly the chemical mixes in slakers and bleach‑neutralizing tanks. A product that is too light may float and delay reaction times; one that is too dense and crystalline might settle before fully reacting. Mills can optimize their recipes by specifying a target bulk density range and working with a supplier who can adjust particle sizing. Explore our sodium sulfite solutions for pulp mills.
Textile finishing plants rely on sodium sulfite to neutralize residual bleach after peroxide bleaching or as a reducing agent in certain dyeing processes. Consistent bulk density ensures reproducibility in automated dispensing systems and minimizes dusting, which is a worker safety concern. The heptahydrate grade, with its higher bulk density and lower dust, is sometimes preferred in open vessel operations, though the extra water content must be factored into heat balances.
Beyond chemistry, bulk density shapes logistics. When importing sodium sulfite from producers like Hailei Chemical in China, buyers must optimize container stuffing plans. With anhydrous sodium sulfite at 900 kg/m³, a 40‑foot container can hold about 50 m³, equivalent to roughly 45 tonnes—well above road weight limits in many countries. Thus, volume is rarely the bottleneck; the container is simply filled to the maximum legal payload, often 25–27 tonnes. However, for lower‑density batches, the same weight might occupy more volume, requiring larger bag dimensions that push against container walls and complicate unloading. Hailei Chemical offers custom packaging: 25 kg woven bags, 1,000–1,200 kg FIBCs, or 50 kg drums—all optimized to fully utilize container space while maintaining material integrity.
Storage conditions also interact with bulk density. Anhydrous sodium sulfite exposed to humidity can absorb moisture, forming clumps that increase local density and disrupt silo flow. Heptahydrate may effloresce in dry environments, shedding water and crumbling into finer particles that shift bulk density unpredictably. Adhering to recommended storage—cool, dry, ventilated— preserves the as‑delivered bulk density and extends shelf life.
To select a reliable partner, procurement teams should pose specific questions during the sourcing process:
A manufacturer that welcomes these questions—like Hailei Fine Chemical—demonstrates the technical depth required for global B2B partnerships.
When analyzing quotes, create a simple landed cost model that factors in freight cost per cubic meter and the active chemical delivered per tonne. A product with a slightly higher price per kilogram but a higher bulk density that reduces the number of containers needed can be more economical overall. Use the sodium sulfite price data you gather along with bulk density to calculate the “cost‑per‑active‑kilogram‑delivered” and you’ll see the true value of a supplier who pays attention to physical parameters.
In summary, sodium sulfite bulk density is far from a trivial spec—it is a critical lever for cost control, process reliability, and safety. By integrating bulk density into your procurement framework and working with a knowledgeable supplier who transparently provides this data, you can eliminate surprises, reduce total cost of ownership, and ensure smooth operations across water treatment, pulp processing, textile finishing, and beyond.
For chemical buyers managing boiler systems, pulp digesters, or textile bleaching lines, the sodium sulfite formula is much more than a simple chemistry question. Na2SO3 represents a workhorse oxygen scavenger, reducing agent, and preservative, but its real-world performance depends entirely on the grade, hydration state, and purity you specify. This guide bridges the gap between the laboratory formula and your plant’s KPIs, helping procurement managers and process engineers make informed sourcing decisions without falling for the common confusion between sulfite and sulfate.
The sodium sulfite formula is Na2SO3, indicating one atom of sulfur bonded to three oxygen atoms, carrying a net 2− charge balanced by two sodium cations. The anhydrous form (CAS 7757-83-7) has a molecular weight of 126.04 g/mol and appears as a white crystalline powder or granular solid. The heptahydrate, Na2SO3·7H2O (CAS 10102-15-5), adds seven water molecules per formula unit, raising the molecular weight to 252.15 g/mol and creating transparent, efflorescent crystals that lose water on exposure to air.
Why does the formula matter for industrial buyers? Because your dosing calculations, storage requirements, and even freight costs hinge on this distinction. If your tender simply requests “sodium sulfite,” you may receive a hydrated product containing less than 50% active Na2SO3 by mass. Listing the exact formula with hydration state in your purchase order is step one in avoiding costly misunderstandings.
The two commercial forms of sodium sulfite are not interchangeable. Each offers distinct advantages depending on your application and logistics:
When you source industrial-grade sodium sulfite, always request a Certificate of Analysis that breaks down the form, purity on a dry basis, and the loss on drying. This simple step prevents your receiving team from accepting a shipment that meets the formula on paper but falls short in practice.
No discussion of the sodium sulfite formula is complete without addressing the persistent mix-up with sodium sulfate (Na2SO4). One additional oxygen atom makes all the difference: sulfite (SO32−, sulfur in +4 oxidation state) is a reducing agent, while sulfate (SO42−, sulfur in +6 oxidation state) is an oxidized, inert by-product. Your boiler’s corrosion control and your pulp mill’s delignification rely on the reducing power of sulfite—sulfate cannot scavenge oxygen or react with lignin in the same way.
Here’s a quick comparison buyers should memorize:
| Property | Sodium Sulfite (Na2SO3) | Sodium Sulfate (Na2SO4) |
|---|---|---|
| Oxidation state of sulfur | +4 (can be oxidized) | +6 (fully oxidized) |
| Industrial role | Reducing agent, oxygen scavenger | Filler, diluent, drying agent |
| Key uses | Boiler water treatment, sulfite pulping, textile neutralizer | Detergents, glass, textile leveling, shampoo thickener |
| Appearance | White crystalline powder | White granular or powder |
| Oxygen scavenging | Yes – reacts rapidly with dissolved O₂ | No |
Many buyers searching for “what is sodium sulfate in shampoo” stumble upon this confusion. Sodium sulfate is used in shampoos and detergents as a thickener and viscosity modifier—it is chemically inert and safe in personal care. Sodium sulfite, by contrast, is a reactive industrial chemical. If you need a reducing agent, purchase the sulfite; if you are formulating cosmetics, you want the sulfate. Knowing this difference can save your company from a costly procurement error.
Understanding the chemical properties of sodium sulfate helps clarify why it cannot replace sulfite in oxygen-sensitive processes:
For procurement teams, the critical takeaway is that “sulfXte” products are completely different chemicals, requiring separate transportation classifications, storage, and handling procedures. Always cross-check the CAS number on the supplier’s SDS against your specification sheet.
One of the largest industrial consumers of sodium sulfite is the pulp and paper industry, where sulfite pulping remains a key technology for producing high-brightness, soft wood pulps. Despite competition from kraft (sulfate) pulping, sulfite mills value the process for its ability to yield pulps with low lignin content and excellent beatability, particularly for dissolving pulps used in rayon, cellophane, and cellulose ethers.
In sulfite pulping, wood chips are cooked under pressure (130–160°C) in an aqueous solution of sulfurous acid (H2SO3) and a base—historically calcium, magnesium, ammonium, or sodium. When sodium sulfite is used (Na-based sulfite process), the active cooking liquor contains sodium bisulfite (NaHSO3) and free SO2. The sulfite ion attacks lignin by sulfonation, breaking the β-O-4 ether bonds that link lignin’s aromatic units, while sulfonation adds hydrophilic sulfonate groups that solubilize the lignin fragments. The result: cellulose fibers are separated with minimal carbohydrate degradation.
Mills that choose the sodium base benefit from the solubility of all reaction products, which avoids the scaling and sludge problems associated with calcium-based sulfite processes. This makes the sodium sulfite formula especially valuable for modern closed-loop pulp mills that need predictable heat recovery and chemical regeneration cycles.
Pulp mill buyers typically specify:
Sodium sulfite from Hailei Chemical meets these demanding specs. Our sodium sulfite for sulfite pulping is produced using a controlled chemical process that minimizes sulfate contamination, ensuring your digester chemistry stays on target.
For power plant chemical buyers, the primary role of sodium sulfite is straightforward: extend boiler life by eliminating dissolved oxygen that drives pitting corrosion. The reaction is fast and quantitative:
2 Na2SO3 + O2 → 2 Na2SO4
Stoichiometrically, 7.88 parts of sodium sulfite (anhydrous) are required to remove one part of dissolved oxygen. In practice, a slight excess is maintained—typically a 20–40 ppm sulfite residual in the boiler water—guaranteeing complete oxygen removal before the water reaches the economizer.
However, the sodium sulfite formula carries an important handling nuance: at high boiler pressures (>900 psig, ~6.2 MPa), sulfite can decompose to form acidic gases (SO2 and H2S), promoting corrosion rather than preventing it. For high-pressure systems, catalyzed sulfite or alternative scavengers like hydrazine or diethylhydroxylamine (DEHA) are often preferred. Still, for the vast majority of low- and medium-pressure industrial boilers, sodium sulfite remains the most cost-effective oxygen scavenger available.
Boiler operators should request a product with a high percentage of the anhydrous form, low iron content, and a Certificate of Analysis showing sulfate by-product below 3%. When you request a sulfite quotation from Hailei, note your boiler pressure and any steam purity requirements so we can match the correct grade.
In textile finishing, hydrogen peroxide bleaching of cotton and cellulosic blends leaves residual peroxide that must be neutralized before dyeing or enzyme finishing. Sodium sulfite offers a clean, effective reducing rinse—it destroys peroxide quickly, leaves no harmful residues, and the resulting sodium sulfate is easily rinsed from the fabric. A typical neutralization bath might contain 1–3 g/L sodium sulfite at 40–60°C for 15–20 minutes. Because the reaction consumes sulfite stoichiometrically, mills can control dosing precisely by measuring redox potential.
Textile buyers often prefer the anhydrous form to avoid introducing additional water into concentrated stock solutions and to keep product weight predictable. Dust-suppressed grades are available for mills with open mixing stations.
The leather industry uses sodium sulfite in unhairing and liming processes, where its mild alkalinity and reducing power help swell hides and loosen hair without the harsh caustic treatment that can damage grain quality. Typically, a 2–5% sodium sulfite on raw hide weight is added to the liming drum. Technical grade purity (96% min) is standard, and both anhydrous and heptahydrate forms are accepted depending on local water hardness and process preference.
In photography, sodium sulfite serves as a preservative in developer solutions, preventing oxidation of the developing agent (e.g., hydroquinone) by dissolved oxygen. Photographic-grade sulfite requires exceptionally low heavy metal content, particularly iron and copper, which would catalyze developer oxidation. While this is a niche market, it still demands the highest purity available—often a special grade exceeding 98% with trace metal specs in the single-digit ppm range.
An industrial buyer’s best defense against off-spec material is a detailed COA that matches the sodium sulfite formula to the intended use. Key parameters to demand from your supplier include:
| Parameter | Typical Specification (Anhydrous, Technical Grade) | Significance |
|---|---|---|
| Na2SO3 content | ≥ 96.0% | Active ingredient; determines dosage rate |
| Na2SO4 (sulfate) | ≤ 2.5% | Inert impurity that reduces scavenging efficiency |
| Na2CO3 (carbonate) | ≤ 0.5% | Can raise pH undesirably in sensitive processes |
| Iron (Fe) | ≤ 20 ppm | Avoids staining in paper and textile applications |
| Loss on drying | ≤ 0.5% (anhydrous) | Confirms minimal moisture uptake during storage |
| Solution clarity | Clear 10% solution | Absence of insoluble contaminants |
| pH (10% solution) | 9.0–10.5 | Ensures correct alkalinity for targeted applications |
When you purchase sodium sulfite from Hailei Chemical, every shipment includes a detailed COA tied to the batch number, so you can audit performance from delivery to process integration.
The sodium sulfite formula’s tendency to oxidize in air means that storage conditions directly impact product quality. Anhydrous sodium sulfite, if left exposed to humid air, will absorb moisture, form lumps, and slowly oxidize to sodium sulfate—reducing the effective scavenging capacity by up to 1% per month under poor conditions. Best practices include:
Heptahydrate crystals tend to effloresce (lose water) and form a white powder on the surface; this is cosmetic and does not significantly alter the active sulfite content, but the free water can complicate feed system design. Buyers who require stable free-flowing granules year-round should specify the anhydrous grade.
As a chemical exporter, Hailei Fine Chemical understands the complexities of moving sodium sulfite across borders. Sodium sulfite (UN number not regulated for transport in most forms, but always check with your freight forwarder) is generally classified as a non-dangerous good for sea freight, though local regulations may impose restrictions. Typical packaging options: 25 kg woven bags with PE liner, 1000 kg supersacks, or bulk in container liners. For ocean freight, moisture control is critical—desiccant packs in containers are recommended for anhydrous product during monsoon-season shipments.
Buyers in the Middle East, South Asia, and Latin America frequently ask about the sodium sulfite formula verification upon arrival. We supply an independent third-party inspection report upon request, using methods like iodometric titration (for sulfite content) and ion chromatography (for sulfate and carbonate impurities). This transparent approach ensures you get exactly what your formula requires.
Your process efficiency and asset protection depend on chemicals that meet spec every time. When you write your next RFQ, be specific: state the sodium sulfite formula you need (Na2SO3 anhydrous or heptahydrate), the minimum purity, and the maximum allowable sulfate and iron levels. Cross-reference the SDS’s CAS number against your specifications to eliminate confusion with sodium sulfate. With a reliable supplier and a clear technical specification, your sodium sulfite deliveries will support your plant’s KPIs rather than cause troubleshooting headaches.
Hailei Fine Chemical has decades of experience supplying industrial-grade sodium sulfite to power plants, pulp mills, and textile finishing operations worldwide. Our product is manufactured under ISO 9001 quality management, with COA-driven traceability and flexible packaging options for any logistics corridor. Whether you need a single container for a trial or a 500-ton annual contract, we’re ready to tailor our supply to your formula requirements.
Ready to secure your next shipment of precisely specified sodium sulfite? Request a quotation today and let our technical sales team propose the optimal grade for your application.
When specifying sodium sulfite bulk density, industrial buyers touch on far more than a simple physical constant. The bulk density of sodium sulfite (Na₂SO₃) directly influences packaging design, freight costs, silo sizing, dosing accuracy, and even the price you negotiate. For procurement managers at power plants, pulp mills, or textile finishing operations, overlooking this parameter can lead to hidden costs and operational inefficiencies. In this guide, we unpack what sodium sulfite bulk density means, how it varies between anhydrous and heptahydrate forms, and why it deserves a prime spot on your technical specification sheet.
Sodium sulfite bulk density refers to the mass per unit volume of the material in its freely settled state, expressed in kilograms per cubic meter (kg/m³) or grams per cubic centimeter (g/cm³). It accounts for the particle size distribution, shape, moisture content, and degree of compaction. Unlike true density, which measures only the solid matter, bulk density includes the interstitial air spaces between granules. For an industrial chemical like sodium sulfite, typical loose bulk densities range from 800 to 1,050 kg/m³ for the anhydrous grade, while the heptahydrate form (Na₂SO₃·7H₂O) often falls between 1,200 and 1,400 kg/m³ due to its crystalline water content. These values shift when the powder is tapped or vibrated—a phenomenon buyers must consider when designing silos or specifying big-bag dimensions.
A buyer who ignores bulk density risks paying for air. Sodium sulfite is sold by weight, but it is shipped and stored by volume. A lower bulk density means fewer kilograms fit into a 25 kg bag, 1-tonne FIBC, or bulk tanker—driving up packaging material costs, warehouse footprint, and freight charges per effective tonne. Conversely, a higher bulk density product may require less storage space and allow more flexible packaging, but could pose challenges in pneumatic conveying systems if it compacts easily. By understanding sodium sulfite bulk density, procurement teams can:
Leading suppliers like Weifang Hailei Fine Chemical Co., Ltd. provide bulk density data as part of the certificate of analysis, enabling data-driven purchasing decisions.
Sodium sulfite is commercially available as anhydrous (Na₂SO₃, 96–98% purity) and heptahydrate (Na₂SO₃·7H₂O). The heptahydrate contains approximately 50% water by weight, forming larger, denser crystals. Its bulk density is therefore significantly higher—often around 1,300 kg/m³ compared to the anhydrous grade’s 900 kg/m³. Buyers using sodium sulfite as an oxygen scavenger in boiler water systems typically prefer anhydrous for its higher active content, but they must account for the lower bulk density when retrofitting storage from a previous heptahydrate source.
The production process (crystallization, drying, milling) determines particle size and shape. Irregular flakes, fine powders, or compacted granules each pack differently. A fine powder may have a lower aerated bulk density but can compact heavily under vibration, creating a wide gap between “loose” and “tapped” densities. For consistent dosing in water treatment or textile bleaching neutralizers, buyers should request both loose and tapped bulk density values from the supplier.
Anhydrous sodium sulfite is hygroscopic and may absorb moisture during transit or storage, leading to caking and a measurable increase in bulk density. Tight moisture specifications (typically ≤0.5% for anhydrous) help maintain predictable material flow properties. Suppliers like Hailei Chemical package the product in moisture-resistant PE-lined bags and advise on proper storage conditions to preserve the original bulk density.
To appreciate the practical impact, consider a 20-foot shipping container. A container with a 25‑tonne payload could hold approximately 27.8 m³ of anhydrous sodium sulfite (assuming 900 kg/m³), but only 19.2 m³ of heptahydrate (at 1,300 kg/m³). The heptahydrate uses about 30% less volume for the same weight—potentially lowering freight costs if volume is the limiting factor. However, since the heptahydrate delivers only half the active Na₂SO₃, the landed cost per kilogram of effective chemical often favors anhydrous. This trade-off is central to sodium sulfite price negotiations. Speaking of which…
When evaluating sodium sulfite price, buyers typically focus on EXW, FOB, or CIF rates per metric tonne. Yet the true cost per functional unit depends on both purity and how much of the product actually arrives in usable form. Bulk density ties into this equation in two ways: first, through freight economics—lower bulk density means more pallets or containers to ship the same net weight; second, through processing losses if poor flowability or caking requires extra handling. A supplier offering a slightly higher unit price but a consistent, high bulk density with free-flowing particles can reduce total landed cost. Smart procurement teams therefore request bulk density specifications alongside chemical purity, heavy metals content, and solubility profiles. For transparent pricing and bulk density data, visit our sodium sulfite product page.
In the world of sodium-based chemicals, confusion is common. A recurring query is “what is sodium sulfate formula” and how it differs from sulfite. Sodium sulfate bears the formula Na₂SO₄ — a fully oxidized, stable salt commonly used in detergents and glassmaking. Sodium sulfite (Na₂SO₃), on the other hand, is a reduced form with strong antioxidant properties. The single oxygen atom difference changes everything: sulfite is a powerful dechlorinating agent and oxygen scavenger; sulfate is practically inert. Another frequent search is “what is sodium sulfide used for”. Sodium sulfide (Na₂S) is a tanning and dehairing agent in leather processing—distinct from sodium sulfite, which is also used in leather preparation but as a reducer for hair-saving methods and pH adjustment. Knowing these applications helps buyers avoid costly misorders.
An even simpler question some newcomers ask: “is salt a sulfite?” No, common table salt is sodium chloride (NaCl) and contains no sulfite group (SO₃²⁻). Sulfites are a class of sulfur‑oxygen compounds used as preservatives and reducing agents. While sodium sulfite is a salt in the chemical sense (a product of acid‑base neutralization), it shares nothing with culinary salt. This distinction matters for safety data sheets and regulatory compliance when handling industrial chemicals.
Reputable suppliers define sodium sulfite bulk density according to recognized methods such as ASTM D7481 (loose bulk density) or ISO 3923. For procurement contracts, a typical specification might read:
These ranges reflect real-world production from a reliable manufacturer like Hailei Chemical. Buyers should align their silo and feeder designs with the supplier’s typical values and request batch-specific COAs for sensitive applications. In boiler water treatment, where feed rates are precisely controlled, even a 5% deviation in bulk density can alter the mass flow from volumetric dosing systems, leading to under‑ or over‑dosing and potential corrosion or deposit issues.
For power plant chemical buyers, sodium sulfite as an oxygen scavenger must be fed consistently into high‑pressure boiler systems. A free‑flowing powder with a stable bulk density ensures volumetric feeders deliver the correct mass per stroke. If the bulk density drops because of an ultra‑fine grind, the same volume contains less active chemical, risking dissolved oxygen breakthrough. Conversely, a densified granule that packs too tightly may cause arching in the feeder hopper. Hailei Chemical produces an anhydrous sodium sulfite with carefully controlled granulation, striking a balance between dissolution rate and material handling—ideal for both batching and continuous treatment.
In pulp and paper mills, sodium sulfite is used in sulfite pulping and as a dechlorination agent. Bulk density here influences how quickly the chemical mixes in slakers and bleach‑neutralizing tanks. A product that is too light may float and delay reaction times; one that is too dense and crystalline might settle before fully reacting. Mills can optimize their recipes by specifying a target bulk density range and working with a supplier who can adjust particle sizing. Explore our sodium sulfite solutions for pulp mills.
Textile finishing plants rely on sodium sulfite to neutralize residual bleach after peroxide bleaching or as a reducing agent in certain dyeing processes. Consistent bulk density ensures reproducibility in automated dispensing systems and minimizes dusting, which is a worker safety concern. The heptahydrate grade, with its higher bulk density and lower dust, is sometimes preferred in open vessel operations, though the extra water content must be factored into heat balances.
Beyond chemistry, bulk density shapes logistics. When importing sodium sulfite from producers like Hailei Chemical in China, buyers must optimize container stuffing plans. With anhydrous sodium sulfite at 900 kg/m³, a 40‑foot container can hold about 50 m³, equivalent to roughly 45 tonnes—well above road weight limits in many countries. Thus, volume is rarely the bottleneck; the container is simply filled to the maximum legal payload, often 25–27 tonnes. However, for lower‑density batches, the same weight might occupy more volume, requiring larger bag dimensions that push against container walls and complicate unloading. Hailei Chemical offers custom packaging: 25 kg woven bags, 1,000–1,200 kg FIBCs, or 50 kg drums—all optimized to fully utilize container space while maintaining material integrity.
Storage conditions also interact with bulk density. Anhydrous sodium sulfite exposed to humidity can absorb moisture, forming clumps that increase local density and disrupt silo flow. Heptahydrate may effloresce in dry environments, shedding water and crumbling into finer particles that shift bulk density unpredictably. Adhering to recommended storage—cool, dry, ventilated— preserves the as‑delivered bulk density and extends shelf life.
To select a reliable partner, procurement teams should pose specific questions during the sourcing process:
A manufacturer that welcomes these questions—like Hailei Fine Chemical—demonstrates the technical depth required for global B2B partnerships.
When analyzing quotes, create a simple landed cost model that factors in freight cost per cubic meter and the active chemical delivered per tonne. A product with a slightly higher price per kilogram but a higher bulk density that reduces the number of containers needed can be more economical overall. Use the sodium sulfite price data you gather along with bulk density to calculate the “cost‑per‑active‑kilogram‑delivered” and you’ll see the true value of a supplier who pays attention to physical parameters.
In summary, sodium sulfite bulk density is far from a trivial spec—it is a critical lever for cost control, process reliability, and safety. By integrating bulk density into your procurement framework and working with a knowledgeable supplier who transparently provides this data, you can eliminate surprises, reduce total cost of ownership, and ensure smooth operations across water treatment, pulp processing, textile finishing, and beyond.
For chemical buyers managing boiler systems, pulp digesters, or textile bleaching lines, the sodium sulfite formula is much more than a simple chemistry question. Na2SO3 represents a workhorse oxygen scavenger, reducing agent, and preservative, but its real-world performance depends entirely on the grade, hydration state, and purity you specify. This guide bridges the gap between the laboratory formula and your plant’s KPIs, helping procurement managers and process engineers make informed sourcing decisions without falling for the common confusion between sulfite and sulfate.
The sodium sulfite formula is Na2SO3, indicating one atom of sulfur bonded to three oxygen atoms, carrying a net 2− charge balanced by two sodium cations. The anhydrous form (CAS 7757-83-7) has a molecular weight of 126.04 g/mol and appears as a white crystalline powder or granular solid. The heptahydrate, Na2SO3·7H2O (CAS 10102-15-5), adds seven water molecules per formula unit, raising the molecular weight to 252.15 g/mol and creating transparent, efflorescent crystals that lose water on exposure to air.
Why does the formula matter for industrial buyers? Because your dosing calculations, storage requirements, and even freight costs hinge on this distinction. If your tender simply requests “sodium sulfite,” you may receive a hydrated product containing less than 50% active Na2SO3 by mass. Listing the exact formula with hydration state in your purchase order is step one in avoiding costly misunderstandings.
The two commercial forms of sodium sulfite are not interchangeable. Each offers distinct advantages depending on your application and logistics:
When you source industrial-grade sodium sulfite, always request a Certificate of Analysis that breaks down the form, purity on a dry basis, and the loss on drying. This simple step prevents your receiving team from accepting a shipment that meets the formula on paper but falls short in practice.
No discussion of the sodium sulfite formula is complete without addressing the persistent mix-up with sodium sulfate (Na2SO4). One additional oxygen atom makes all the difference: sulfite (SO32−, sulfur in +4 oxidation state) is a reducing agent, while sulfate (SO42−, sulfur in +6 oxidation state) is an oxidized, inert by-product. Your boiler’s corrosion control and your pulp mill’s delignification rely on the reducing power of sulfite—sulfate cannot scavenge oxygen or react with lignin in the same way.
Here’s a quick comparison buyers should memorize:
| Property | Sodium Sulfite (Na2SO3) | Sodium Sulfate (Na2SO4) |
|---|---|---|
| Oxidation state of sulfur | +4 (can be oxidized) | +6 (fully oxidized) |
| Industrial role | Reducing agent, oxygen scavenger | Filler, diluent, drying agent |
| Key uses | Boiler water treatment, sulfite pulping, textile neutralizer | Detergents, glass, textile leveling, shampoo thickener |
| Appearance | White crystalline powder | White granular or powder |
| Oxygen scavenging | Yes – reacts rapidly with dissolved O₂ | No |
Many buyers searching for “what is sodium sulfate in shampoo” stumble upon this confusion. Sodium sulfate is used in shampoos and detergents as a thickener and viscosity modifier—it is chemically inert and safe in personal care. Sodium sulfite, by contrast, is a reactive industrial chemical. If you need a reducing agent, purchase the sulfite; if you are formulating cosmetics, you want the sulfate. Knowing this difference can save your company from a costly procurement error.
Understanding the chemical properties of sodium sulfate helps clarify why it cannot replace sulfite in oxygen-sensitive processes:
For procurement teams, the critical takeaway is that “sulfXte” products are completely different chemicals, requiring separate transportation classifications, storage, and handling procedures. Always cross-check the CAS number on the supplier’s SDS against your specification sheet.
One of the largest industrial consumers of sodium sulfite is the pulp and paper industry, where sulfite pulping remains a key technology for producing high-brightness, soft wood pulps. Despite competition from kraft (sulfate) pulping, sulfite mills value the process for its ability to yield pulps with low lignin content and excellent beatability, particularly for dissolving pulps used in rayon, cellophane, and cellulose ethers.
In sulfite pulping, wood chips are cooked under pressure (130–160°C) in an aqueous solution of sulfurous acid (H2SO3) and a base—historically calcium, magnesium, ammonium, or sodium. When sodium sulfite is used (Na-based sulfite process), the active cooking liquor contains sodium bisulfite (NaHSO3) and free SO2. The sulfite ion attacks lignin by sulfonation, breaking the β-O-4 ether bonds that link lignin’s aromatic units, while sulfonation adds hydrophilic sulfonate groups that solubilize the lignin fragments. The result: cellulose fibers are separated with minimal carbohydrate degradation.
Mills that choose the sodium base benefit from the solubility of all reaction products, which avoids the scaling and sludge problems associated with calcium-based sulfite processes. This makes the sodium sulfite formula especially valuable for modern closed-loop pulp mills that need predictable heat recovery and chemical regeneration cycles.
Pulp mill buyers typically specify:
Sodium sulfite from Hailei Chemical meets these demanding specs. Our sodium sulfite for sulfite pulping is produced using a controlled chemical process that minimizes sulfate contamination, ensuring your digester chemistry stays on target.
For power plant chemical buyers, the primary role of sodium sulfite is straightforward: extend boiler life by eliminating dissolved oxygen that drives pitting corrosion. The reaction is fast and quantitative:
2 Na2SO3 + O2 → 2 Na2SO4
Stoichiometrically, 7.88 parts of sodium sulfite (anhydrous) are required to remove one part of dissolved oxygen. In practice, a slight excess is maintained—typically a 20–40 ppm sulfite residual in the boiler water—guaranteeing complete oxygen removal before the water reaches the economizer.
However, the sodium sulfite formula carries an important handling nuance: at high boiler pressures (>900 psig, ~6.2 MPa), sulfite can decompose to form acidic gases (SO2 and H2S), promoting corrosion rather than preventing it. For high-pressure systems, catalyzed sulfite or alternative scavengers like hydrazine or diethylhydroxylamine (DEHA) are often preferred. Still, for the vast majority of low- and medium-pressure industrial boilers, sodium sulfite remains the most cost-effective oxygen scavenger available.
Boiler operators should request a product with a high percentage of the anhydrous form, low iron content, and a Certificate of Analysis showing sulfate by-product below 3%. When you request a sulfite quotation from Hailei, note your boiler pressure and any steam purity requirements so we can match the correct grade.
In textile finishing, hydrogen peroxide bleaching of cotton and cellulosic blends leaves residual peroxide that must be neutralized before dyeing or enzyme finishing. Sodium sulfite offers a clean, effective reducing rinse—it destroys peroxide quickly, leaves no harmful residues, and the resulting sodium sulfate is easily rinsed from the fabric. A typical neutralization bath might contain 1–3 g/L sodium sulfite at 40–60°C for 15–20 minutes. Because the reaction consumes sulfite stoichiometrically, mills can control dosing precisely by measuring redox potential.
Textile buyers often prefer the anhydrous form to avoid introducing additional water into concentrated stock solutions and to keep product weight predictable. Dust-suppressed grades are available for mills with open mixing stations.
The leather industry uses sodium sulfite in unhairing and liming processes, where its mild alkalinity and reducing power help swell hides and loosen hair without the harsh caustic treatment that can damage grain quality. Typically, a 2–5% sodium sulfite on raw hide weight is added to the liming drum. Technical grade purity (96% min) is standard, and both anhydrous and heptahydrate forms are accepted depending on local water hardness and process preference.
In photography, sodium sulfite serves as a preservative in developer solutions, preventing oxidation of the developing agent (e.g., hydroquinone) by dissolved oxygen. Photographic-grade sulfite requires exceptionally low heavy metal content, particularly iron and copper, which would catalyze developer oxidation. While this is a niche market, it still demands the highest purity available—often a special grade exceeding 98% with trace metal specs in the single-digit ppm range.
An industrial buyer’s best defense against off-spec material is a detailed COA that matches the sodium sulfite formula to the intended use. Key parameters to demand from your supplier include:
| Parameter | Typical Specification (Anhydrous, Technical Grade) | Significance |
|---|---|---|
| Na2SO3 content | ≥ 96.0% | Active ingredient; determines dosage rate |
| Na2SO4 (sulfate) | ≤ 2.5% | Inert impurity that reduces scavenging efficiency |
| Na2CO3 (carbonate) | ≤ 0.5% | Can raise pH undesirably in sensitive processes |
| Iron (Fe) | ≤ 20 ppm | Avoids staining in paper and textile applications |
| Loss on drying | ≤ 0.5% (anhydrous) | Confirms minimal moisture uptake during storage |
| Solution clarity | Clear 10% solution | Absence of insoluble contaminants |
| pH (10% solution) | 9.0–10.5 | Ensures correct alkalinity for targeted applications |
When you purchase sodium sulfite from Hailei Chemical, every shipment includes a detailed COA tied to the batch number, so you can audit performance from delivery to process integration.
The sodium sulfite formula’s tendency to oxidize in air means that storage conditions directly impact product quality. Anhydrous sodium sulfite, if left exposed to humid air, will absorb moisture, form lumps, and slowly oxidize to sodium sulfate—reducing the effective scavenging capacity by up to 1% per month under poor conditions. Best practices include:
Heptahydrate crystals tend to effloresce (lose water) and form a white powder on the surface; this is cosmetic and does not significantly alter the active sulfite content, but the free water can complicate feed system design. Buyers who require stable free-flowing granules year-round should specify the anhydrous grade.
As a chemical exporter, Hailei Fine Chemical understands the complexities of moving sodium sulfite across borders. Sodium sulfite (UN number not regulated for transport in most forms, but always check with your freight forwarder) is generally classified as a non-dangerous good for sea freight, though local regulations may impose restrictions. Typical packaging options: 25 kg woven bags with PE liner, 1000 kg supersacks, or bulk in container liners. For ocean freight, moisture control is critical—desiccant packs in containers are recommended for anhydrous product during monsoon-season shipments.
Buyers in the Middle East, South Asia, and Latin America frequently ask about the sodium sulfite formula verification upon arrival. We supply an independent third-party inspection report upon request, using methods like iodometric titration (for sulfite content) and ion chromatography (for sulfate and carbonate impurities). This transparent approach ensures you get exactly what your formula requires.
Your process efficiency and asset protection depend on chemicals that meet spec every time. When you write your next RFQ, be specific: state the sodium sulfite formula you need (Na2SO3 anhydrous or heptahydrate), the minimum purity, and the maximum allowable sulfate and iron levels. Cross-reference the SDS’s CAS number against your specifications to eliminate confusion with sodium sulfate. With a reliable supplier and a clear technical specification, your sodium sulfite deliveries will support your plant’s KPIs rather than cause troubleshooting headaches.
Hailei Fine Chemical has decades of experience supplying industrial-grade sodium sulfite to power plants, pulp mills, and textile finishing operations worldwide. Our product is manufactured under ISO 9001 quality management, with COA-driven traceability and flexible packaging options for any logistics corridor. Whether you need a single container for a trial or a 500-ton annual contract, we’re ready to tailor our supply to your formula requirements.
Ready to secure your next shipment of precisely specified sodium sulfite? Request a quotation today and let our technical sales team propose the optimal grade for your application.
When specifying sodium sulfite bulk density, industrial buyers touch on far more than a simple physical constant. The bulk density of sodium sulfite (Na₂SO₃) directly influences packaging design, freight costs, silo sizing, dosing accuracy, and even the price you negotiate. For procurement managers at power plants, pulp mills, or textile finishing operations, overlooking this parameter can lead to hidden costs and operational inefficiencies. In this guide, we unpack what sodium sulfite bulk density means, how it varies between anhydrous and heptahydrate forms, and why it deserves a prime spot on your technical specification sheet.
Sodium sulfite bulk density refers to the mass per unit volume of the material in its freely settled state, expressed in kilograms per cubic meter (kg/m³) or grams per cubic centimeter (g/cm³). It accounts for the particle size distribution, shape, moisture content, and degree of compaction. Unlike true density, which measures only the solid matter, bulk density includes the interstitial air spaces between granules. For an industrial chemical like sodium sulfite, typical loose bulk densities range from 800 to 1,050 kg/m³ for the anhydrous grade, while the heptahydrate form (Na₂SO₃·7H₂O) often falls between 1,200 and 1,400 kg/m³ due to its crystalline water content. These values shift when the powder is tapped or vibrated—a phenomenon buyers must consider when designing silos or specifying big-bag dimensions.
A buyer who ignores bulk density risks paying for air. Sodium sulfite is sold by weight, but it is shipped and stored by volume. A lower bulk density means fewer kilograms fit into a 25 kg bag, 1-tonne FIBC, or bulk tanker—driving up packaging material costs, warehouse footprint, and freight charges per effective tonne. Conversely, a higher bulk density product may require less storage space and allow more flexible packaging, but could pose challenges in pneumatic conveying systems if it compacts easily. By understanding sodium sulfite bulk density, procurement teams can:
Leading suppliers like Weifang Hailei Fine Chemical Co., Ltd. provide bulk density data as part of the certificate of analysis, enabling data-driven purchasing decisions.
Sodium sulfite is commercially available as anhydrous (Na₂SO₃, 96–98% purity) and heptahydrate (Na₂SO₃·7H₂O). The heptahydrate contains approximately 50% water by weight, forming larger, denser crystals. Its bulk density is therefore significantly higher—often around 1,300 kg/m³ compared to the anhydrous grade’s 900 kg/m³. Buyers using sodium sulfite as an oxygen scavenger in boiler water systems typically prefer anhydrous for its higher active content, but they must account for the lower bulk density when retrofitting storage from a previous heptahydrate source.
The production process (crystallization, drying, milling) determines particle size and shape. Irregular flakes, fine powders, or compacted granules each pack differently. A fine powder may have a lower aerated bulk density but can compact heavily under vibration, creating a wide gap between “loose” and “tapped” densities. For consistent dosing in water treatment or textile bleaching neutralizers, buyers should request both loose and tapped bulk density values from the supplier.
Anhydrous sodium sulfite is hygroscopic and may absorb moisture during transit or storage, leading to caking and a measurable increase in bulk density. Tight moisture specifications (typically ≤0.5% for anhydrous) help maintain predictable material flow properties. Suppliers like Hailei Chemical package the product in moisture-resistant PE-lined bags and advise on proper storage conditions to preserve the original bulk density.
To appreciate the practical impact, consider a 20-foot shipping container. A container with a 25‑tonne payload could hold approximately 27.8 m³ of anhydrous sodium sulfite (assuming 900 kg/m³), but only 19.2 m³ of heptahydrate (at 1,300 kg/m³). The heptahydrate uses about 30% less volume for the same weight—potentially lowering freight costs if volume is the limiting factor. However, since the heptahydrate delivers only half the active Na₂SO₃, the landed cost per kilogram of effective chemical often favors anhydrous. This trade-off is central to sodium sulfite price negotiations. Speaking of which…
When evaluating sodium sulfite price, buyers typically focus on EXW, FOB, or CIF rates per metric tonne. Yet the true cost per functional unit depends on both purity and how much of the product actually arrives in usable form. Bulk density ties into this equation in two ways: first, through freight economics—lower bulk density means more pallets or containers to ship the same net weight; second, through processing losses if poor flowability or caking requires extra handling. A supplier offering a slightly higher unit price but a consistent, high bulk density with free-flowing particles can reduce total landed cost. Smart procurement teams therefore request bulk density specifications alongside chemical purity, heavy metals content, and solubility profiles. For transparent pricing and bulk density data, visit our sodium sulfite product page.
In the world of sodium-based chemicals, confusion is common. A recurring query is “what is sodium sulfate formula” and how it differs from sulfite. Sodium sulfate bears the formula Na₂SO₄ — a fully oxidized, stable salt commonly used in detergents and glassmaking. Sodium sulfite (Na₂SO₃), on the other hand, is a reduced form with strong antioxidant properties. The single oxygen atom difference changes everything: sulfite is a powerful dechlorinating agent and oxygen scavenger; sulfate is practically inert. Another frequent search is “what is sodium sulfide used for”. Sodium sulfide (Na₂S) is a tanning and dehairing agent in leather processing—distinct from sodium sulfite, which is also used in leather preparation but as a reducer for hair-saving methods and pH adjustment. Knowing these applications helps buyers avoid costly misorders.
An even simpler question some newcomers ask: “is salt a sulfite?” No, common table salt is sodium chloride (NaCl) and contains no sulfite group (SO₃²⁻). Sulfites are a class of sulfur‑oxygen compounds used as preservatives and reducing agents. While sodium sulfite is a salt in the chemical sense (a product of acid‑base neutralization), it shares nothing with culinary salt. This distinction matters for safety data sheets and regulatory compliance when handling industrial chemicals.
Reputable suppliers define sodium sulfite bulk density according to recognized methods such as ASTM D7481 (loose bulk density) or ISO 3923. For procurement contracts, a typical specification might read:
These ranges reflect real-world production from a reliable manufacturer like Hailei Chemical. Buyers should align their silo and feeder designs with the supplier’s typical values and request batch-specific COAs for sensitive applications. In boiler water treatment, where feed rates are precisely controlled, even a 5% deviation in bulk density can alter the mass flow from volumetric dosing systems, leading to under‑ or over‑dosing and potential corrosion or deposit issues.
For power plant chemical buyers, sodium sulfite as an oxygen scavenger must be fed consistently into high‑pressure boiler systems. A free‑flowing powder with a stable bulk density ensures volumetric feeders deliver the correct mass per stroke. If the bulk density drops because of an ultra‑fine grind, the same volume contains less active chemical, risking dissolved oxygen breakthrough. Conversely, a densified granule that packs too tightly may cause arching in the feeder hopper. Hailei Chemical produces an anhydrous sodium sulfite with carefully controlled granulation, striking a balance between dissolution rate and material handling—ideal for both batching and continuous treatment.
In pulp and paper mills, sodium sulfite is used in sulfite pulping and as a dechlorination agent. Bulk density here influences how quickly the chemical mixes in slakers and bleach‑neutralizing tanks. A product that is too light may float and delay reaction times; one that is too dense and crystalline might settle before fully reacting. Mills can optimize their recipes by specifying a target bulk density range and working with a supplier who can adjust particle sizing. Explore our sodium sulfite solutions for pulp mills.
Textile finishing plants rely on sodium sulfite to neutralize residual bleach after peroxide bleaching or as a reducing agent in certain dyeing processes. Consistent bulk density ensures reproducibility in automated dispensing systems and minimizes dusting, which is a worker safety concern. The heptahydrate grade, with its higher bulk density and lower dust, is sometimes preferred in open vessel operations, though the extra water content must be factored into heat balances.
Beyond chemistry, bulk density shapes logistics. When importing sodium sulfite from producers like Hailei Chemical in China, buyers must optimize container stuffing plans. With anhydrous sodium sulfite at 900 kg/m³, a 40‑foot container can hold about 50 m³, equivalent to roughly 45 tonnes—well above road weight limits in many countries. Thus, volume is rarely the bottleneck; the container is simply filled to the maximum legal payload, often 25–27 tonnes. However, for lower‑density batches, the same weight might occupy more volume, requiring larger bag dimensions that push against container walls and complicate unloading. Hailei Chemical offers custom packaging: 25 kg woven bags, 1,000–1,200 kg FIBCs, or 50 kg drums—all optimized to fully utilize container space while maintaining material integrity.
Storage conditions also interact with bulk density. Anhydrous sodium sulfite exposed to humidity can absorb moisture, forming clumps that increase local density and disrupt silo flow. Heptahydrate may effloresce in dry environments, shedding water and crumbling into finer particles that shift bulk density unpredictably. Adhering to recommended storage—cool, dry, ventilated— preserves the as‑delivered bulk density and extends shelf life.
To select a reliable partner, procurement teams should pose specific questions during the sourcing process:
A manufacturer that welcomes these questions—like Hailei Fine Chemical—demonstrates the technical depth required for global B2B partnerships.
When analyzing quotes, create a simple landed cost model that factors in freight cost per cubic meter and the active chemical delivered per tonne. A product with a slightly higher price per kilogram but a higher bulk density that reduces the number of containers needed can be more economical overall. Use the sodium sulfite price data you gather along with bulk density to calculate the “cost‑per‑active‑kilogram‑delivered” and you’ll see the true value of a supplier who pays attention to physical parameters.
In summary, sodium sulfite bulk density is far from a trivial spec—it is a critical lever for cost control, process reliability, and safety. By integrating bulk density into your procurement framework and working with a knowledgeable supplier who transparently provides this data, you can eliminate surprises, reduce total cost of ownership, and ensure smooth operations across water treatment, pulp processing, textile finishing, and beyond.
For chemical buyers managing boiler systems, pulp digesters, or textile bleaching lines, the sodium sulfite formula is much more than a simple chemistry question. Na2SO3 represents a workhorse oxygen scavenger, reducing agent, and preservative, but its real-world performance depends entirely on the grade, hydration state, and purity you specify. This guide bridges the gap between the laboratory formula and your plant’s KPIs, helping procurement managers and process engineers make informed sourcing decisions without falling for the common confusion between sulfite and sulfate.
The sodium sulfite formula is Na2SO3, indicating one atom of sulfur bonded to three oxygen atoms, carrying a net 2− charge balanced by two sodium cations. The anhydrous form (CAS 7757-83-7) has a molecular weight of 126.04 g/mol and appears as a white crystalline powder or granular solid. The heptahydrate, Na2SO3·7H2O (CAS 10102-15-5), adds seven water molecules per formula unit, raising the molecular weight to 252.15 g/mol and creating transparent, efflorescent crystals that lose water on exposure to air.
Why does the formula matter for industrial buyers? Because your dosing calculations, storage requirements, and even freight costs hinge on this distinction. If your tender simply requests “sodium sulfite,” you may receive a hydrated product containing less than 50% active Na2SO3 by mass. Listing the exact formula with hydration state in your purchase order is step one in avoiding costly misunderstandings.
The two commercial forms of sodium sulfite are not interchangeable. Each offers distinct advantages depending on your application and logistics:
When you source industrial-grade sodium sulfite, always request a Certificate of Analysis that breaks down the form, purity on a dry basis, and the loss on drying. This simple step prevents your receiving team from accepting a shipment that meets the formula on paper but falls short in practice.
No discussion of the sodium sulfite formula is complete without addressing the persistent mix-up with sodium sulfate (Na2SO4). One additional oxygen atom makes all the difference: sulfite (SO32−, sulfur in +4 oxidation state) is a reducing agent, while sulfate (SO42−, sulfur in +6 oxidation state) is an oxidized, inert by-product. Your boiler’s corrosion control and your pulp mill’s delignification rely on the reducing power of sulfite—sulfate cannot scavenge oxygen or react with lignin in the same way.
Here’s a quick comparison buyers should memorize:
| Property | Sodium Sulfite (Na2SO3) | Sodium Sulfate (Na2SO4) |
|---|---|---|
| Oxidation state of sulfur | +4 (can be oxidized) | +6 (fully oxidized) |
| Industrial role | Reducing agent, oxygen scavenger | Filler, diluent, drying agent |
| Key uses | Boiler water treatment, sulfite pulping, textile neutralizer | Detergents, glass, textile leveling, shampoo thickener |
| Appearance | White crystalline powder | White granular or powder |
| Oxygen scavenging | Yes – reacts rapidly with dissolved O₂ | No |
Many buyers searching for “what is sodium sulfate in shampoo” stumble upon this confusion. Sodium sulfate is used in shampoos and detergents as a thickener and viscosity modifier—it is chemically inert and safe in personal care. Sodium sulfite, by contrast, is a reactive industrial chemical. If you need a reducing agent, purchase the sulfite; if you are formulating cosmetics, you want the sulfate. Knowing this difference can save your company from a costly procurement error.
Understanding the chemical properties of sodium sulfate helps clarify why it cannot replace sulfite in oxygen-sensitive processes:
For procurement teams, the critical takeaway is that “sulfXte” products are completely different chemicals, requiring separate transportation classifications, storage, and handling procedures. Always cross-check the CAS number on the supplier’s SDS against your specification sheet.
One of the largest industrial consumers of sodium sulfite is the pulp and paper industry, where sulfite pulping remains a key technology for producing high-brightness, soft wood pulps. Despite competition from kraft (sulfate) pulping, sulfite mills value the process for its ability to yield pulps with low lignin content and excellent beatability, particularly for dissolving pulps used in rayon, cellophane, and cellulose ethers.
In sulfite pulping, wood chips are cooked under pressure (130–160°C) in an aqueous solution of sulfurous acid (H2SO3) and a base—historically calcium, magnesium, ammonium, or sodium. When sodium sulfite is used (Na-based sulfite process), the active cooking liquor contains sodium bisulfite (NaHSO3) and free SO2. The sulfite ion attacks lignin by sulfonation, breaking the β-O-4 ether bonds that link lignin’s aromatic units, while sulfonation adds hydrophilic sulfonate groups that solubilize the lignin fragments. The result: cellulose fibers are separated with minimal carbohydrate degradation.
Mills that choose the sodium base benefit from the solubility of all reaction products, which avoids the scaling and sludge problems associated with calcium-based sulfite processes. This makes the sodium sulfite formula especially valuable for modern closed-loop pulp mills that need predictable heat recovery and chemical regeneration cycles.
Pulp mill buyers typically specify:
Sodium sulfite from Hailei Chemical meets these demanding specs. Our sodium sulfite for sulfite pulping is produced using a controlled chemical process that minimizes sulfate contamination, ensuring your digester chemistry stays on target.
For power plant chemical buyers, the primary role of sodium sulfite is straightforward: extend boiler life by eliminating dissolved oxygen that drives pitting corrosion. The reaction is fast and quantitative:
2 Na2SO3 + O2 → 2 Na2SO4
Stoichiometrically, 7.88 parts of sodium sulfite (anhydrous) are required to remove one part of dissolved oxygen. In practice, a slight excess is maintained—typically a 20–40 ppm sulfite residual in the boiler water—guaranteeing complete oxygen removal before the water reaches the economizer.
However, the sodium sulfite formula carries an important handling nuance: at high boiler pressures (>900 psig, ~6.2 MPa), sulfite can decompose to form acidic gases (SO2 and H2S), promoting corrosion rather than preventing it. For high-pressure systems, catalyzed sulfite or alternative scavengers like hydrazine or diethylhydroxylamine (DEHA) are often preferred. Still, for the vast majority of low- and medium-pressure industrial boilers, sodium sulfite remains the most cost-effective oxygen scavenger available.
Boiler operators should request a product with a high percentage of the anhydrous form, low iron content, and a Certificate of Analysis showing sulfate by-product below 3%. When you request a sulfite quotation from Hailei, note your boiler pressure and any steam purity requirements so we can match the correct grade.
In textile finishing, hydrogen peroxide bleaching of cotton and cellulosic blends leaves residual peroxide that must be neutralized before dyeing or enzyme finishing. Sodium sulfite offers a clean, effective reducing rinse—it destroys peroxide quickly, leaves no harmful residues, and the resulting sodium sulfate is easily rinsed from the fabric. A typical neutralization bath might contain 1–3 g/L sodium sulfite at 40–60°C for 15–20 minutes. Because the reaction consumes sulfite stoichiometrically, mills can control dosing precisely by measuring redox potential.
Textile buyers often prefer the anhydrous form to avoid introducing additional water into concentrated stock solutions and to keep product weight predictable. Dust-suppressed grades are available for mills with open mixing stations.
The leather industry uses sodium sulfite in unhairing and liming processes, where its mild alkalinity and reducing power help swell hides and loosen hair without the harsh caustic treatment that can damage grain quality. Typically, a 2–5% sodium sulfite on raw hide weight is added to the liming drum. Technical grade purity (96% min) is standard, and both anhydrous and heptahydrate forms are accepted depending on local water hardness and process preference.
In photography, sodium sulfite serves as a preservative in developer solutions, preventing oxidation of the developing agent (e.g., hydroquinone) by dissolved oxygen. Photographic-grade sulfite requires exceptionally low heavy metal content, particularly iron and copper, which would catalyze developer oxidation. While this is a niche market, it still demands the highest purity available—often a special grade exceeding 98% with trace metal specs in the single-digit ppm range.
An industrial buyer’s best defense against off-spec material is a detailed COA that matches the sodium sulfite formula to the intended use. Key parameters to demand from your supplier include:
| Parameter | Typical Specification (Anhydrous, Technical Grade) | Significance |
|---|---|---|
| Na2SO3 content | ≥ 96.0% | Active ingredient; determines dosage rate |
| Na2SO4 (sulfate) | ≤ 2.5% | Inert impurity that reduces scavenging efficiency |
| Na2CO3 (carbonate) | ≤ 0.5% | Can raise pH undesirably in sensitive processes |
| Iron (Fe) | ≤ 20 ppm | Avoids staining in paper and textile applications |
| Loss on drying | ≤ 0.5% (anhydrous) | Confirms minimal moisture uptake during storage |
| Solution clarity | Clear 10% solution | Absence of insoluble contaminants |
| pH (10% solution) | 9.0–10.5 | Ensures correct alkalinity for targeted applications |
When you purchase sodium sulfite from Hailei Chemical, every shipment includes a detailed COA tied to the batch number, so you can audit performance from delivery to process integration.
The sodium sulfite formula’s tendency to oxidize in air means that storage conditions directly impact product quality. Anhydrous sodium sulfite, if left exposed to humid air, will absorb moisture, form lumps, and slowly oxidize to sodium sulfate—reducing the effective scavenging capacity by up to 1% per month under poor conditions. Best practices include:
Heptahydrate crystals tend to effloresce (lose water) and form a white powder on the surface; this is cosmetic and does not significantly alter the active sulfite content, but the free water can complicate feed system design. Buyers who require stable free-flowing granules year-round should specify the anhydrous grade.
As a chemical exporter, Hailei Fine Chemical understands the complexities of moving sodium sulfite across borders. Sodium sulfite (UN number not regulated for transport in most forms, but always check with your freight forwarder) is generally classified as a non-dangerous good for sea freight, though local regulations may impose restrictions. Typical packaging options: 25 kg woven bags with PE liner, 1000 kg supersacks, or bulk in container liners. For ocean freight, moisture control is critical—desiccant packs in containers are recommended for anhydrous product during monsoon-season shipments.
Buyers in the Middle East, South Asia, and Latin America frequently ask about the sodium sulfite formula verification upon arrival. We supply an independent third-party inspection report upon request, using methods like iodometric titration (for sulfite content) and ion chromatography (for sulfate and carbonate impurities). This transparent approach ensures you get exactly what your formula requires.
Your process efficiency and asset protection depend on chemicals that meet spec every time. When you write your next RFQ, be specific: state the sodium sulfite formula you need (Na2SO3 anhydrous or heptahydrate), the minimum purity, and the maximum allowable sulfate and iron levels. Cross-reference the SDS’s CAS number against your specifications to eliminate confusion with sodium sulfate. With a reliable supplier and a clear technical specification, your sodium sulfite deliveries will support your plant’s KPIs rather than cause troubleshooting headaches.
Hailei Fine Chemical has decades of experience supplying industrial-grade sodium sulfite to power plants, pulp mills, and textile finishing operations worldwide. Our product is manufactured under ISO 9001 quality management, with COA-driven traceability and flexible packaging options for any logistics corridor. Whether you need a single container for a trial or a 500-ton annual contract, we’re ready to tailor our supply to your formula requirements.
Ready to secure your next shipment of precisely specified sodium sulfite? Request a quotation today and let our technical sales team propose the optimal grade for your application.
For Francophone industrial buyers and global procurement managers seeking a reliable oxygen scavenger, le sulfite de sodium (sodium sulfite, Na2SO3) remains a cornerstone of effective boiler water treatment and numerous industrial processes. Whether you are evaluating chemical specifications, optimizing dosing in high-pressure steam systems, or comparing bulk supply options from China, a thorough understanding of sodium sulfite’s chemistry, applications, and procurement logistics is essential. This comprehensive guide explores every critical aspect of le sulfite de sodium—from its chemical formula and anhydrous properties to its reaction in water and the key factors you must consider when you buy sodium sulphite as a powder or crystal. As a leading Chinese manufacturer, Hailei Chemical provides industrial-grade sodium sulfite with consistent quality, backed by technical expertise that helps you achieve efficient and cost-effective operations.
The term le sulfite de sodium is the French equivalent of sodium sulfite, a widely used inorganic compound. Its chemical formula is Na2SO3, indicating two sodium ions (Na+) and one sulfite ion (SO32−). In solid form, it appears as a white crystalline powder or granular material, highly soluble in water, and moderately stable when kept dry. Sodium sulfite is commercially available in two principal grades: anhydrous (Na2SO3, no water of crystallization) and heptahydrate (Na2SO3·7H2O).
When dissolved in water, sodium sulfite dissociates completely into sodium and sulfite ions. The sulfite ion is a potent reducing agent, which is the key to its industrial value. In boiler water chemistry, sulfite reacts rapidly with dissolved oxygen to form harmless sulfate (SO42−), thereby preventing oxygen-induced corrosion of steel surfaces. The same reducing property makes le sulfite de sodium invaluable in textile bleaching neutralization, pulp processing, and several niche applications such as photographic developers and leather dehairing.
For buyers, understanding the sodium sulfite formula and its implications is the first step in selecting the correct product for your process. The anhydrous form delivers a higher concentration of active sulfite per unit mass, while the heptahydrate offers easier handling in some ambient conditions but contains over 50% water by weight. At Hailei Chemical, we supply sodium sulfite with a guaranteed Na2SO3 purity of 96–98%, available in both anhydrous and heptahydrate forms. Visit our sodium sulfite product page for detailed technical data and packaging options.
A common question from procurement teams is what is sodium sulfite anhydrous and how it differs from the hydrated version. The answer lies in water content and logistics.
As a buyer, your decision hinges on freight costs, storage conditions, and process requirements. Anhydrous sodium sulfite offers more “bang for your buck” in terms of active chemical delivered per container, typically lowering total landed cost despite a higher unit price. Hailei Chemical can supply both forms from our production base in Weifang, China, and our technical team can help you evaluate the total cost of ownership before you place a bulk order. For a full breakdown of technical specifications, review our product data sheet.
The most critical industrial use of le sulfite de sodium is as an oxygen scavenger in steam-generating boilers. Understanding sodium sulfite in water and its reaction kinetics is essential for achieving effective corrosion protection while avoiding excessive chemical waste.
When sodium sulfite is injected into boiler feedwater, it quickly dissociates and then reacts with dissolved oxygen according to the following stoichiometric equation:
2Na2SO3 + O2 → 2Na2SO4
Theoretically, 7.88 parts of pure Na2SO3 are required to remove 1 part of dissolved oxygen. In practice, an excess of sulfite is maintained—typically 20–40 mg/L as SO3 residual in the boiler water—to ensure complete oxygen removal and to provide a safety margin against momentary oxygen ingress. The reaction rate is strongly dependent on temperature and pH; at ambient feedwater temperatures, the reaction is slow, but it accelerates dramatically above 70°C and with the aid of a catalyst (cobalt or copper salts) when treating cold water.
Because the anhydrous form dissolves quickly and provides consistent active content, it is the first choice for most modern power plants and industrial boiler houses. Hailei Chemical supplies high-purity sodium sulfite that dissolves rapidly with minimal insolubles, ensuring trouble-free injection. For custom dosing guidance or to discuss your specific boiler operating pressure and feedwater quality, our engineers are available through your free quote request.
While water treatment accounts for the largest market share, le sulfite de sodium finds diverse use across multiple industries. Understanding these applications can help buyers source a single chemical for multiple in-house processes or qualify a supplier who meets broader industry standards.
In chemical pulping, sodium sulfite is used as a cooking liquor component in neutral sulfite semi-chemical (NSSC) processes, where it helps delignify wood chips mildly, preserving more hemicellulose and producing high-yield pulp for corrugated medium. It also serves as a reducing agent in bleaching sequences to neutralize residual chlorine or chlorine dioxide, preventing fiber degradation.
After bleaching cotton or synthetic textiles with hydrogen peroxide or chlorine-based bleaches, sodium sulfite acts as an antichlor to remove excess oxidants, which could otherwise weaken fibers or interfere with subsequent dyeing. The result is a more uniform finish and longer-lasting fabric quality. Textile finishing plants particularly value the anhydrous grade for its rapid dissolving and precise chemical control.
In black-and-white photographic developers, sodium sulfite serves as a preservative that scavenges oxygen and prevents the developing agent (such as hydroquinone) from oxidizing prematurely. While digital imaging has reduced demand, there remains a niche market for high-purity sodium sulfite from industrial chemical suppliers.
Sodium sulfite is added to lime-sulfide solutions in the leather beamhouse to accelerate the unhairing of hides while reducing the required concentration of sodium sulfide. This reduces environmental load and improves working conditions. Leather tanneries in North Africa and Francophone West Africa are significant consumers of le sulfite de sodium, often importing directly from Chinese manufacturers.
Beyond boiler feedwater, sodium sulfite is employed to dechlorinate municipal drinking water or treated wastewater before discharge. It neutralizes free chlorine and chloramines more rapidly than sulfur dioxide gas, making it a safer choice for small to medium plants. The anhydrous powder is dosed as a dilute solution to meet dechlorination targets.
For each application, purity requirements may differ slightly. Photographic grade might require lower iron and heavy metal content, while water treatment grades focus on consistent activity. Hailei Chemical can provide tailored specifications upon request, ensuring your purchase matches the end-use without paying for unneeded premium purity. Contact us to discuss your application-specific needs.
Procurement professionals looking to buy sodium sulphite in bulk must scrutinize beyond the nominal purity figure. The following quality parameters directly influence performance, handling, and regulatory compliance:
| Parameter | Typical Value (Anhydrous) | Importance |
|---|---|---|
| Na2SO3 Assay | ≥96.0% | Direct indicator of oxygen-scavenging capacity; lower assay means higher consumption and cost. |
| Sodium Sulfate (Na2SO4) | ≤2.5% | Inert byproduct from oxidation; high sulfate increases dissolved solids and blowdown. |
| Sodium Carbonate (Na2CO3) | ≤0.5% | Minor alkalinity contributor; excessive levels may affect pH control. |
| Iron (Fe) | ≤0.003% | Critical for photographic and some textile applications; can catalyze unwanted oxidation. |
| Heavy Metals (as Pb) | ≤0.002% | Required for food-contact (e.g., dechlorination of potable water) and environmental compliance. |
| Water Insoluble Matter | ≤0.03% | Avoids clogging of dosing lines and strainers. |
| pH of 1% solution | 8.5–9.5 | Mild alkalinity aids boiler water chemistry. |
When evaluating Chinese suppliers, request a Certificate of Analysis (CoA) for each batch and verify that the testing methods follow GB/T 9005 or ISO 3627 standards. Reputable manufacturers like Hailei Chemical provide full traceability and will accommodate third-party inspection at our factory or loading port. Bulk shipments typically arrive in 25 kg HDPE bags, 1-ton FIBCs, or custom packaging, all with inner liners that minimize moisture ingress. Our sales team can help you decide the optimal packaging and freight arrangement to match your port facilities and storage inventory. For immediate requirements, request a quote for sodium sulphite today.
Global buyers across Francophone Africa, Europe, and Asia are increasingly turning to Chinese exporters to secure consistent, cost-effective supplies of le sulfite de sodium. However, successful sourcing requires more than comparing prices; you must navigate product specifications, logistics, and regulatory considerations.
China is the world’s largest producer of sodium sulfite, leveraging integrated sulfur and soda ash supply chains. This means competitive pricing, flexible production scales, and short lead times. Hailei Chemical, located in Weifang, Shandong Province, benefits from proximity to major raw material sources and the Qingdao port, one of China’s busiest chemical export hubs.
Sodium sulfite is classified as a non-hazardous chemical for transport under most regulations (IMDG, ADR). It does not require DG labeling, which simplifies freight booking and lowers shipping costs. Still, proper shipper’s declaration and a Safety Data Sheet (SDS) in the local language are mandatory. Hailei Chemical provides SDS in English, French, and other languages, along with all necessary certificates (CoA, country of origin, REACH compliance if applicable).
To mitigate the risk of receiving off-spec material, buyers should:
Hailei Chemical has a long track record of meeting international specifications for water treatment, pulp, and textile customers. We treat every order as a partnership, providing technical support, regular quality updates, and flexible logistics coordination. When you’re ready to secure your supply chain for le sulfite de sodium, use our online form to get a detailed offer within one business day.
Choosing the right manufacturer for your sodium sulfite supply is critical for uninterrupted plant operations. Hailei Chemical offers distinct advantages for B2B buyers:
Our sodium sulfite is already trusted by power plants in West Africa, textile mills in Southeast Asia, and leather processing units across the Mediterranean. We welcome you to join this community of satisfied clients. Visit our dedicated product page for complete specifications, and when you’re ready to discuss volumes, pricing, and delivery schedules, submit your request for a quotation—we’ll respond with a tailored proposal.
If you’ve searched for “what is sodium metal sulfite,” you’re not alone. This phrase often appears in procurement queries, industrial forums, and even import documentation, but it’s actually a misnomer. The correct chemical name is sodium sulfite (Na2SO3), an inorganic compound widely used in water treatment, pulp and paper, textiles, and leather processing. As a senior chemical strategist at Hailei Chemical’s sodium sulfite division, I’ve encountered this confusion frequently—buyers mixing up sodium sulfite with sodium metal or sodium sulfide. In this guide, I’ll clarify the terminology, break down the industrial value of sodium sulfite, and provide a supplier evaluation framework that procurement professionals in power generation, paper mills, and textile finishing plants can use to secure high-purity material at competitive pricing.
Let’s address the term head-on: “sodium metal sulfite” does not exist as a recognized chemical name. The confusion likely stems from two sources: a literal translation of the French term le sulfite de sodium, where “sodium” is the metal component, and conflation with sodium sulfide (Na2S)—a completely different reducing agent known for hide dehairing and, oddly, home remedies for ingrown toenails (search “how does sodium sulfide help ingrown toenails” and you’ll see why ambiguity is dangerous). Properly, sodium sulfite is a sodium salt of sulfurous acid. In purchasing documents, always use the correct CAS number 7757-83-7 to avoid supply chain errors. This clarity is critical when issuing RFQs, preparing LC documents, or communicating with Chinese manufacturers where translation mistakes can lead to wrong shipments.
Trade professionals need to distinguish between the two commercially dominant forms of sodium sulfite, because their water content directly affects dosing calculations, freight cost, and storage conditions.
When you see “what is sodium sulfite anhydrous” in trade queries, the buyer is usually seeking the water-free material for oxygen scavenging where hydration would add unnecessary bulk. As a supplier, Hailei Chemical recommends anhydrous for boiler applications and heptahydrate for large-volume liquid formulation processes.
Sodium sulfite’s industrial utility rests on its strong reducing properties. Understanding each application enables buyers to set the right technical specifications in procurement contracts.
Power plants and industrial steam generators rely on sodium sulfite as a cost-effective oxygen scavenger. The reaction: 2Na2SO3 + O2 → 2Na2SO4. At typical boiler pressures up to 6.2 MPa, sulfite efficiently removes dissolved oxygen, preventing pitting corrosion. Catalyzed grades (often with cobalt salts) accelerate the reaction at low temperatures, but uncatalyzed anhydrous sulfite remains the economic backbone for high-temperature systems. When sourcing, verify that the product meets GB/T 2449-2015 or equivalent ASTM standards for water treatment chemicals. A purity of ≥96% with low iron (<0.005%) and insolubles (<0.05%) is standard for this use.
In mechanical pulping and semichemical processes, sodium sulfite softens lignin while preserving cellulose fiber length. It’s used in neutral sulfite semichemical (NSSC) pulping, producing corrugating medium-grade pulp. Procurement managers in this sector often request a technical-grade anhydrous sulfite with controlled pH (9–10 in 10% solution) and low chloride content to avoid corrosion in digesters. Hailei Chemical’s bulk sodium sulfite is regularly shipped to paper mills in Southeast Asia and Africa, typically in 25 kg woven bags or 1-ton FIBCs with PE liners.
After cotton or synthetic fiber bleaching with hydrogen peroxide, residual peroxide must be neutralized before dyeing. Sodium sulfite rapidly reduces H2O2 to water, preventing dye oxidation. Textile finishing plants prefer the heptahydrate form for easy dissolution in warm water (35–40°C). A clear solution and absence of heavy metal catalysts are crucial; look for iron ≤0.002% and copper ≤0.0005% in the certificate of analysis.
Sodium sulfite, often in combination with sodium sulfide, assists in breaking the disulfide bonds in keratin, loosening hair from hides. The unhairing bath typically uses 2–5% sodium sulfite on hide weight. Here, consistent particle size and rapid solubility are important to avoid residue on the limed pelts. Tanners evaluate the “solubility index” – all our commercial lots pass a 50 g/L clear dissolution test in 20°C water within 2 minutes.
In black-and-white photography, sodium sulfite functions as a preservative in developer solutions, protecting developing agents like hydroquinone from aerial oxidation. The photographic grade demands ultra-high purity (≥99%, low heavy metals), which Hailei Chemical can supply upon request, though this is a niche market compared to the above bulk applications.
When procuring sodium sulfite, don’t rely solely on “purity 96–98%.” A detailed COA should include:
Always request a third-party inspection (SGS, Bureau Veritas) for bulk shipments. At Hailei, we provide pre-shipment samples and full documentation. Our typical particle size for anhydrous sulfite is 98% passing 60 mesh, ensuring good dissolution kinetics.
Sourcing sodium sulfite from Chinese exporters offers cost advantages but demands rigorous due diligence. Here’s a five-point framework:
We consistently ship high-purity sodium sulfite to South Korea, Vietnam, India, and Russia, with a documented on-time delivery rate above 98%.
For procurement teams unfamiliar with Chinese exports, here are the essentials:
To help with cost estimation, as of 2025 Q2, the FOB price for technical-grade anhydrous sodium sulfite (96% min) ranges between $350–$450 per metric ton, depending on packaging and purity. Heptahydrate is typically $50–$80 lower due to water weight. Request a formal quotation for your volume through our quick quote form.
It’s worth briefly addressing a search term that often appears alongside “what is sodium metal sulfite”: “how does sodium sulfide help ingrown toenails.” Sodium sulfide (Na2S) is a corrosive, alkaline compound used in leather dehairing and ore flotation—not a medical treatment. Some unverified home remedies mention sodium sulfide paste to “soften” the nail, but this is dangerous and can cause severe chemical burns. Sodium sulfite and sodium sulfide are chemically distinct; sodium sulfite is a mild reducing agent, whereas sodium sulfide is a potent caustic. Industrial buyers must understand this difference to avoid purchasing the wrong chemical. Always verify CAS numbers: sodium sulfite 7757-83-7, sodium sulfide 1313-82-2.
A related search is “uses of sodium sulphate.” Sodium sulfate (Na2SO4) is the oxidation product of sodium sulfite—it’s used as a filler in detergents and in the Kraft pulping process, but it lacks the reducing power required for oxygen scavenging or dye neutralization. Buyers looking for a reducing agent must specifically request sodium sulfite, not sulfate. We frequently help clients differentiate these two salts during the procurement process, preventing costly mistakes.
Weifang Hailei Fine Chemical Co., Ltd. has been a reliable exporter of sulfite and sulfate salts since 2008. Our sodium sulfite range is manufactured under strict process control, ensuring lot-to-lot consistency. Our dedicated quality lab tests each batch for the parameters outlined above, and we can tailor packaging and documentation to your market requirements, including le sulfite de sodium labels for Francophone West Africa. Our sales engineers speak French and English to serve clients across Africa, the Middle East, and Southeast Asia.
When you source from Hailei, you get more than a product—you gain a supply partner who understands the nuances of industrial chemical sourcing, from “what is sodium metal sulfite” confusion to complex boiler dosing protocols. We maintain safety stock at our bonded warehouses in Qingdao to enable rapid shipment against short lead-time orders.
Whether you need anhydrous sodium sulfite for boiler water oxygen scavenging, heptahydrate for textile bleaching neutralization, or any other application, Hailei Chemical is prepared to meet your specs. Request a quote today and include your required quantity, target purity, and preferred packaging. Our team will respond within 24 hours with a detailed offer, COA specimen, and logistics plan. Partner with a supplier that clarifies the chemistry and delivers on quality—choose Hailei Chemical.