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E221 Sodium sulphite is the inorganic compound with the chemical formula Na2SO3.
A white, water-soluble solid, E221 Sodium sulphite is used commercially as an antioxidant and preservative.
E221 Sodium sulphite is also suitable for the softening of lignin in the pulping and refining processes of wood and lignocellulosic materials.
CAS: 7757-83-7
MF: Na2O3S
MW: 126.04
EINECS: 231-821-4
Synonyms: anhydroussodiumsulfite;disodiumsulfite;exsiccatedsodiumsulfite;natriisulphis;natriumsulfid;natriumsulfit;natriumsulfurosum;sodiumsulfite(2:1)
A heptahydrate is also known but E221 Sodium sulphite is less useful because of its greater susceptibility toward oxidation by air.
As a soluble sodium salt of sulfurous acid, E221 Sodium sulphite shows blenching, de-sulfurizing and dechlorinating properties which is widely applied in various fields.
E221 Sodium sulphite is primarily used in the pulp and papermaking industry due to its blenching activity.
E221 Sodium sulphite can serve as a good additive to help preserve the fresh appearance of good products.
Besides, E221 Sodium sulphite is a component in many pharmaceuticals, which is effective to maintain the potency and stability of drugs.
E221 Sodium sulphite can also be applied for water treatment as an oxygen scavenger agent and applied in flue gas desulfurization and preservation of photo developer solutions, etc.
A white solid,Na2SO3, existing in an anhydrousform (r.d. 2.63) and as a heptahydrate(r.d. 1.59).
E221 Sodium sulphite is solublein water and because it is readily oxidizedit is widely used as a convenientreducing agent.
E221 Sodium sulphite is preparedby reacting sulphur dioxide with eithersodium carbonate or sodium hydroxide.
Dilute mineral acids reversethis process and release sulphur dioxide.
E221 Sodium sulphite is used as ableaching agent in textiles and inpaper manufacture.
E221 Sodium sulphite's use as an antioxidantin some canned foodstuffsgives rise to a slightly sulphuroussmell immediately on opening, butits use is prohibited in meats or foodsthat contain vitamin B1.
E221 Sodium sulphite solutions are occasionally usedas biological preservatives.
An inorganic sodium salt having sulfite as the counterion.
White odorless powder.
Density 2.633 g / cm3.
Moderately toxic. Sinks in water and dissolves slowly.
Also transported as a heptahydrate Na2SO3.7H2O.
E221 Sodium sulphite is a salt that is used as a food additive and in the chemical industry.
E221 Sodium sulphite has been used to study the toxicity of sodium salts and their effect on the cardiovascular system.
E221 Sodium sulphite is also used as a diagnostic agent in ethylene diamine tests, which are used to detect fatty acid levels in blood serum.
The process optimization of sodium citrate production has been studied using E221 Sodium sulphite heptahydrate.
Hydrochloric acid can be used to remove sulfur dioxide from sodium sulfite heptahydrate, producing anhydrous sodium sulfate.
Sodium carbonate can be produced by adding water to anhydrous sodium sulfate, forming a solution of hydrogen ions and hydroxide ions.
Sodium carbonate can also be produced through the reaction of anhydrous sodium with carbon dioxide gas or calcium oxide.
Hydrogen bonds between molecules may be disrupted by adding hydrochloric acid to anhydrous sodium sulfate, leading to the formation of diphenyl ether
E221 Sodium sulphite, known as sodium sulfite, is widely used in various industries, including food processing, pharmaceuticals, and manufacturing.
E221 Sodium sulphite is a food additive categorized under chemical preservatives.
E221 Sodium sulphite is a sodium salt of sulfurous acid, appearing as an unstable white powder that reacts with oxygen to form sulfate.
In acidic conditions, E221 Sodium sulphite forms sulfurous acid, which has preservative, oxidizing, and bleaching properties but can also reduce the vitamin content in foods.
Illegally, this preservative may be used to mask bacterial degradation in meat.
E221 Sodium sulphite is a highly effective reducing and bleaching agent.
E221 Sodium sulphite is used in the photographic industry as oxidation protection for developer solutions, as an anti-corrosion agent in water treatment and as an antichlorine in the textile industry.
Additionally, E221 Sodium sulphite is applied as a food preservative, providing effective protection against oxidation and spoilage.
BASF offers E221 Sodium sulphite in various grades, all of which meet the highest standards of quality and purity.
Sulfur dioxide and sulphites are the most common intolerance triggers among chemical food additives.
They can trigger so-called sulphite asthma with bronchial constrictions and swelling of the airways in very sensitive allergy sufferers.
However, E221 Sodium sulphite can also lead to sneezing a runny nose, hives, other skin irritations, and headaches.
So-called anaphylactic shocks with collapse and circulatory collapse were also observed; after a death in Canada, the use of sulfur additives in restaurants was banned.
Some researchers also suspect that some inflammatory, chronic bowel diseases could be causally related to the consumption of foods preserved with sulfur-containing substances.
So-called sulfur-reducing Desulfovibrio bacteria in the intestine may be the cause of damage to the intestinal mucosa.
When foods are treated with sodium metabisulphite, such as for bleaching parboiled rice, the vital vitamin B1 (thiamine) is destroyed.
According to some studies, the same additive is also suspected of disrupting the functions of the cells in the intestinal mucosa and thus promoting inflammatory processes in the intestine.
E221 Sodium sulphite is a soluble sodium salt of sulfurous acid and its chemical formula is Na2SO3.
Used in food processing to sterilize fermentation equipment and food containers to inhibit undesirable micro-organisms growing.
E221 Sodium sulphites are added to pre-peeled and sliced/chopped apples and potatoes to prevent oxidative discoloration and control enzymic browning.
E221 Sodium sulphites are used in processing sugar beet, corn sweeteners, food starches and gelatine.
In some countries E221 Sodium sulphites are added to fresh sausages to control Enterobacteriaceae, including Salmonella.
E221 Sodium sulphites also preserve the bright-red colour of meat by inhibiting the oxidation of myoglobin to metamyoglobin.
This will reduce the B1, Thiamine content in sulfite treated meat products.
E221 Sodium sulphite Chemical Properties
Melting point: 500 °C
density: 2.63
bulk density: 1480kg/m3
refractive index: 1,484
storage temp.: Store at +5°C to +30°C.
solubility: H2O: 1 M at 20 °C, clear, colorless
form: Solid
Specific Gravity: 2.633
color: White to slightly yellow
Odor: Odorless
PH Range: 9.0 - 10.5 at 126 g/l at 25 °C
PH: 9.0-10.5 (25℃, 1M in H2O)
Water Solubility 23 g/100 mL (20 ºC)
Sensitive: Hygroscopic
Merck: 14,8682
Stability: Stable. Incompatible with strong acids. Moisture and air sensitive.
Cosmetics Ingredients Functions: REDUCING ANTIOXIDANT HAIR WAVING OR STRAIGHTENING
InChI: 1S/2Na.H2O3S/c;;1-4(2)3/h;;(H2,1,2,3)/q2*+1;/p-2
InChIKey: GEHJYWRUCIMESM-UHFFFAOYSA-L
CAS DataBase Reference: 7757-83-7(CAS DataBase Reference)
NIST Chemistry Reference: sodium sulfite(7757-83-7)
EPA Substance Registry System: E221 Sodium sulphite (7757-83-7)
Absorption: cut-off at 265nm in H2O at 1M
E221 Sodium sulphite, Na2S03, is a white,water-soluble, crystalline solid with a sulfurous, salty taste.
E221 Sodium sulphite decomposes when heated.
E221 Sodium sulphite is used as a source of sulfite,as a chemical intermediate and food preservative, in medicine and paper manufacturing, in photographic developing, and as a bleaching agent in the textile industry.
Most boiler operators use sodium sulfite for chemicals cavenging of oxygen in the feedwater.
Because E221 Sodium sulphite decomposes into acidic gases at the high temperatures that accompany high pressures, sodium sulfite should not be used for this purpose at pressures above 122atm (12.4MPa,or 1.8 ksi).
E221 Sodium sulphite occurs as an odorless white powder or hexagonal prisms.
Note that the commercially available E221 Sodium sulphite is often presented as a white to tan- or pink-colored powder that would not conform to the pharmacopeial specification.
E221 Sodium sulphite acts as a strong preservative and antioxidant.
E221 Sodium sulphite effectively inhibits the growth of bacteria, mold and yeast, so food products retain their quality for a longer period of time.
In addition, E221 Sodium sulphite prevents oxidation of fats and vitamins, which is crucial for preserving the nutritional value of products.
Structure
According to X-ray crystallography E221 Sodium sulphite heptahydrate features pyramidal SO32- centers.
The S-O distances are 1.50 and the O-S-O angles are near 106º.
Uses
E221 Sodium sulphite is an antioxidant, used as a preservative except with meats.
E221 Sodium sulphite is also used for water treatment and in photography and textile bleaching.
These white crystals were prepared by passing sulfurous gas over moist sodium carbonate.
E221 Sodium sulphite is soluble in water but less so in alcohol.
E221 Sodium sulphite was used as a preservative for alkaline developers and as a hypo clearing agent in photographic printing.
E221 Sodium sulphite has anti-septic, preservative, and anti-oxidant properties.
E221 Sodium sulphite is also a topical anti-fungal.
Paper industry (semichemical pulp), reduc- ing agent (dyes), water treatment, photographic developer, food preservative and antioxidant, tex- tile bleaching (antichlor).
E221 Sodium sulphite is primarily used in the pulp and paper industry.
E221 Sodium sulphite has been also applied in the thermomechanical conversion of wood to fibres (defibration) for producing medium density fibreboards (MDF).
As an oxygen scavenger agent, E221 Sodium sulphite is used to treat water being fed to steam boilers to avoid corrosion problems, in the photographic industry, it protects developer solutions from oxidation and (as hypo clear solution) to wash fixer (sodium thiosulfate) from film and photo-paper emulsions.
As a reducing agent E221 Sodium sulphite is used in the textile industry as a bleaching, desulfurizing, and dechlorinating agent (e.g. in swimming pools).
E221 Sodium sulphite's reducing properties are exploited in its use as a preservative to prevent dried fruit from discoloring, and for preserving meats.
E221 Sodium sulphite is used as a reagent in sulfonation and sulfomethylation agent.
E221 Sodium sulphite is used in the production of sodium thiosulfate.
The Wellman–Lord process utilizes sodium sulfite for flue gas desulfurization.
E221 Sodium sulphite is used in many food industries.
E221 Sodium sulphite is added to wines to prevent fermentation and maintain clarity.
In fruit and vegetable processing, E221 Sodium sulphite protects against darkening and color loss.
In the production of juices, beverages and canned goods, E221 Sodium sulphite helps preserve freshness and prevents the growth of unwanted microorganisms.
Pharmaceutical Applications
E221 Sodium sulphite is used as an antioxidant in applications similar to those for sodium metabisulfite.
E221 Sodium sulphite is also an effective antimicrobial preservative, particularly against fungi at low pH (0.1% w/v of sodium sulfite is used).
E221 Sodium sulphite is used in cosmetics, food products, and pharmaceutical applications such as parenteral formulations, inhalations, oral formulations, and topical preparations.
Production Methods
E221 Sodium sulphite is prepared by reacting sulfur dioxide gas with sodium hydroxide solution.
The solid material is obtained by evaporation of water.
Further neutralization with sodium hydroxide while keeping the temperature above 33.6°C leads to crystallization of the anhydrous sodium sulfite (below this temperature the heptahydrate form is obtained).
Reactivity Profile
E221 Sodium sulphite is a reducing agent, particularly under basic conditions.
Reacts with oxidizing agents such as peroxides, epoxides, oxoacids.
Emits toxic fumes of sodium oxide and oxides of sulfur if heated to decomposition.
Health Hazard
When ingested, solutions cause gastric irritation by the liberation of sulfurous acid.
Because of rapid oxidation to sulfate, sulfites are well tolerated until large doses are reached; then violent colic and diarrhea, circulatory disturbances, central nervous depression, and death can occur.
Contact allergens
E221 Sodium sulphite is mainly used in photographic developers, for fixing prints, bleaching textile fibers, as a reducer in manufacturing dyes, as a remover of Cl in bleached textiles and paper, and as a preservative in the food industry for meat, egg yolks, and so on.
Preparation
E221 Sodium sulphite can be prepared by treating a solution of sodium hydroxide with sulfur dioxide.
When conducted in warm water, Na2SO3 initially precipitates as a white solid.
With more SO2, the solid dissolves to give the disulfite, which crystallizes upon cooling.
SO2 + 2 NaOH → Na2SO3 + H2O
E221 Sodium sulphite is made industrially by treating sulfur dioxide with a solution of sodium carbonate.
The overall reaction is:
SO2 + Na2CO3 → Na2SO3 + CO2
Reactions
E221 Sodium sulphite is primarily used as a mild reducing agent.
The heptahydrate crystals effloresce in warm dry air.
Heptahydrate crystals also oxidize in air to form E221 Sodium sulphite.
The anhydrous form is more resistant to oxidation by air.
