Introduction to sodium bisulfite.
Sodium bisulfite is an inorganic compound with the chemical formula NaHSO3, which is a white crystalline powder with an unpleasant odor of sulfur dioxide, mainly used as a bleaching agent, preservative, antioxidant, etc. This article will introduce the preparation, properties, applications and safety of sodium bisulfite in detail.
1. Preparation of sodium bisulfite.
Sodium bisulfite can be prepared by different methods, the most commonly used method is the reaction of sodium sulfate with hydrogen sulfide. The reaction needs to be carried out under high temperature and high pressure conditions, and the reaction equation is as follows:
na2so4 + h2s → nahso3 + nahs
Second, the properties of sodium bisulfite.
1.Physical.
Sodium bisulfite is a white crystalline powder, with an unpleasant smell of sulfur dioxide, soluble in water, and the aqueous solution is acidic. The density is 1483g cm, melting point 136.
2.Chemical properties.
Sodium bisulfite is reducible and can react with strong oxidants to produce sodium sulfate, sulfur dioxide, and water. Under acidic conditions, sodium bisulfite can release sulfur dioxide gas. In addition, sodium bisulfite can also be complexed with metal ions to form complexes.
3. Application of sodium bisulfite.
1.Bleacher.
Sodium bisulfite has a bleaching effect and can be used for bleaching in textile, paper and other industries. The bleaching principle is to combine with colored substances to form unstable complexes, and at the same time release sulfur dioxide gas to oxidize and decompose colored substances.
2.Preservative.
Sodium bisulfite is reducible, able to consume oxygen in food, inhibit the growth of microorganisms, and thus play a preservative role. It can be used for the preservation of food, such as the preservation of kimchi, jam, etc.
3.Antioxidant.
Sodium bisulfite can react with oxidants, thus acting as an antioxidant. In the food industry, it can be used as an antioxidant to delay the oxidative deterioration of food. In addition, it also has applications in the pharmaceutical industry.
4. Safety of sodium bisulfiteAlthough sodium bisulfite is a relatively safe chemical, it still has certain toxicity. Long-term exposure to high concentrations of sodium bisulfite may cause irritation of mucous membranes such as eyes, nose, and throat, as well as symptoms such as headache, dizziness, and nausea. Therefore, safety precautions should be taken when producing, storing and using sodium bisulfite. Food bleach