White powder.
Hazard class 3.
by covered transport
in dry unheated warehouse premises
| Grades | China | GOST 195-77, amend. 1-2 | Photographic Grade, Belarus TU VU | |||
| Indicator | 98% | Food Standard GB1894-2005 | Grade “ChDA” | Grade “Ch” | Premium grade | First grade |
| Sodium sulfite (Na2SO3), not less than, % | 98% | 96% | 98% | 96% | 97.5% | 96% |
| Sodium sulfate (Na2SO4), not more than, % | 1.5% | — | — | — | — | — |
| Water-insoluble substances, not more than, % | 0.02 | — | 0.003 | 0.01 | 0.01 | 0.02 |
| Alkali calculated as Na2CO3, not more than, % | 0.3 | 0.6 | 0.05 | 0.1 | 0.08 | 0.4 |
| Mass fraction of thiosulfates (S2O3), %, not more than | — | — | 0.2 | — | 0.004 | 0.2 |
| Mass fraction of iron (Fe), %, not more than | 0.003 | 0.01 | 0.0005 | 0.001 | 0.003 | 0.005 |
| Mass fraction of arsenic (As), %, not more than | 0.0001 | 0.0002 | 0.00002 | 0.0001 | — | — |
| Mass fraction of heavy metals (Pb), %, not more than | 0.001 | 0.001 | 0.0005 | 0.001 | 0.0005 | 0.002 |
Sodium sulfite has other names: sodium sulphite, disodium sulfite, disodium salt of sulfurous acid, sodium salt of sulfurous acid. The international name is sodium sulfite, disodium sulfite. Its main properties used in industry are as a strong reducing agent, antioxidant, and strong bleaching effect. It is a white powder (turns yellow upon oxidation) that dissolves well in water. It is stable in open air at room temperature. It gradually oxidizes on contact with air.
Sodium sulfitE Na2SO3 should be distinguished from sodium sulfidE Na2S. The latter (sulfide) forms when sodium sulfite reacts with air or water.
Sodium sulfite was already used for food preservation in ancient Rome. But the real boom in its use began with the appearance of photography in the 19th century. Sodium sulfite became an indispensable component in film development, and to this day it is actively used in this field. It was also actively used in paper production in the 19th century, but today it has been replaced in most factories due to improvements in technological processes. In pulp and paper production today it is used in only about 10% of total output.
Through the reaction between sulfur dioxide and sodium carbonate at a temperature of about 40 degrees. Followed by the addition of caustic soda and an increase in temperature. The anhydrous salt is then obtained.
Sodium sulfite is also a by-product in phenol production processes.
| Nitric acid "p.a." (57 %) TU 2612-046-057 61643-95 |
| Ammonia water "analytical grade" (25-27%) |
| Technical Powdered Lignosulfonate |
| Zinc chloride 98% (corresponds GOST 4529-78) |
| Ammonium bifluoride 98% |
Yes, sodium sulfite and disodium sulfite are names for the same substance with the formula Na₂SO₃. Commercial documents may also use the name disodium salt of sulfurous acid. When purchasing, it is important to check not only the name but also GOST 195-77, the grade, the mass fraction of Na₂SO₃, the content of sodium sulfate, alkali, iron, heavy metals, arsenic and water-insoluble substances. This helps accurately match the batch to the enterprise’s requirements.
Sodium sulfite and sodium sulfide are different substances, although the names sound similar. Sodium sulfite has the formula Na₂SO₃, while sodium sulfide has the formula Na₂S. They differ in chemical composition, properties, hazard level, storage conditions and behaviour in solutions. Therefore it is better to state the full name, formula, GOST and required grade of the product in the request and contract.
When receiving anhydrous sodium sulfite, the integrity of the bags, labelling, production date, quality certificate and the batch’s compliance with GOST 195-77 are checked. Laboratory control looks at the mass fraction of Na₂SO₃, sulfates, alkali, thiosulfates, iron, arsenic, heavy metals and water-insoluble substances. Visually, the product should be a white powder without wetting, dense lumps or foreign inclusions. If the powder has yellowed, the batch should be checked for signs of oxidation before being transferred into use.
Anhydrous sodium sulfite is stored in a dry, unheated warehouse, in sealed factory packaging and protected from moisture. On contact with air, the product can gradually oxidise, so opened packaging should not be left open. Bags are placed on pallets, separately from acids, oxidisers, water sources and materials that could contaminate the batch. For a wholesale buyer, the quality certificate, labelling, packaging integrity and traceability from receipt through to transfer into production are important.
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