25 Sodium Sulfite Uses: Facts You Should Know!

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Sodium sulfite (Na2SO3) is a white crystalline, water soluble inorganic compound. It is produced using NaOH and SO2 in laboratories. Let us see the uses of Na2SO3.

Uses of Sodium sulfite includes;

  • Food preservative
  • Paper making
  • Photography
  • Aquatic treatment
  • Bleaching
  • Cosmetics
  • Industrial chemistry
  • Metallurgy
  • Tanning

This article focuses on the main uses of sodium sulfite.

Food preservative

  • Na2SO3 is primarily used as food additive for food preservation. E.g. for preservation of dried fruit from discoloration.
  • The anti-polyphenol oxidase activity of Na2SO3 helps food from spoilage. The browning of different fruits and vegetables, like cauliflower is prevented using Na2SO3.
  • Some vitamins in food are destroyed by Na2SO3 by reducing them.

Paper making

Na2SO3 was used in paper industries for pulp making.The Na2SO3 solution and raw materials are cooked together at certain temperature and pressure to make pulp.Nowadays less than 10% pulp production is making use of Na2SO3.

Photography

  • In photographic films for preservation of developing agents, Na2SO3 is used.
  • Na2SO3 is used as blackener for negative intensification.
  • To wash fixer from films and photo-paper, Na2SO3 is used.

Aquatic treatment

  • Na2SO3 can remove dissolved oxygen (DO) in water.
  • In waste water treating boilers Na2SO3 is used as they prevent corrosion.
  • The environmental stability, low cost and non-toxicity of Na2SO3 is used for this purpose.
  • Using Na2SO3 chlorine from swimming pools is removed.

Bleaching

  • Na2SO3 exhibits dechlorinating, de-sulfurizing and bleaching properties due to its reducing property.
  • In printing and dyeing industries Na2SO3 is used as bleaching agent.
  • Na2SO3 also helps to stiffen the clothes.
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Structure of Na2SO3

Cosmetics

  • Na2SO3 is used along with sodium sulfate and sodium meta bisulfite for hair straightening and waving purposes due to anti-oxidant nature.
  • Hair bleaches, tints, hair dyes etc. contain Na2SO3.
  • To prevent discoloration of hair formulations Na2SO3 is used.

Industrial chemistry

  • Na2SO3 is used as chain initiators for chain reactions and for producing alkane sulfonic acids etc. E.g. alkyl bromides with Na2SO3.
  • Sodium thiosulfate is produced by boiling sulfur and Na2SO3.
  • To remove residual chlorine in brine production, Na2SO3 is used.
  • In TNT processing Na2SO3 is used as refiners.
  • Na2SO3 is used as sulfonating agent.
  • Corrosion inhibitors are coupled with Na2SO3 to enhance their property.

Metallurgy

Na2SO3 is used as an inhibitor in metallurgy. Equimolar mixtures of Na2SO3 and zinc sulfate is an effective inhibitor for iron sphalerite.

Tanning

Na2SO3 is used in leather treatment to increase resistance, water proofing etc. as it makes the leather soft and plump.

Conclusion

Sodium sulfite, Na2SO3 is used in food, cloth, and chemical industries. It is mainly used for food preservation and as anti-oxidant. It is a low-cost, convenient and low-toxic inorganic compound.