LIQUID SULFUR DIOXIDE
Other names EC # 231-195-2
CAS NO# 7446-09-5
Molecular weight] 64.07
It is irritating and smothering colorless, relative density 2.264(0℃).m.p. -72.7℃, b.p. -10℃.vapor tension 338.32kPa, at 338.32kPa, its water solubility is 8.5%(25℃).
Sulfur dioxide, chemical compound, SO2, a colorless gas with a pungent,
suffocating odor. It is readily soluble in cold water, sparingly soluble in hot
water, and soluble in alcohol, acetic acid, and sulfuric acid. It is corrosive
to organic materials and dissolves in water to form sulfurous acid, H2SO3.
Sulfur dioxide is used in bleaching and in chemical manufacture and as a
refrigerant and a food preservative, e.g., for fumigating fruit. It may be
produced by reaction of sulfur with oxygen, e.g., by burning sulfur in air, and
it is often produced during the roasting of sulfide ores, e.g., in zinc
smelting. Sulfur dioxide is a dangerous air pollutant because of its corrosive
properties; it irritates the eyes, nose, and lungs. It is produced by
combustion of coal, fuel oil, and gasoline, since these fuels contain sulfur.
The sulfur content of a fuel can be reduced by refining, so that less sulfur
dioxide is emitted when the fuel is burned
Our suppliers are the best supplier in the country for the O2 "KURUM International sh.a" and for Sulfur raw matirial "ARMO sh.a" the national pretrolium company.
Precursor to sulfuric acid
Sulfur dioxide is an intermediate in the production of sulfuric acid, being converted to sulfur trioxide, and then tooleum, which is made into sulfuric acid. Sulfur dioxide for this purpose is made when sulfur combines with oxygen. The method of converting sulfur dioxide to sulfuric acid is called the contact process. Several billion kilograms are produced annually for this purpose.
As a preservative
Sulfur dioxide is sometimes used as a preservative for dried apricots and other dried fruits owing to its antimicrobialproperties, and it is sometimes called E220 when used in this way. As a preservative, it maintains the appearance of the fruit and prevents rotting.
Sulfur dioxide is an important compound in winemaking, and is designated as parts per million in wine, E number: E220. It is present even in so-called unsulphurated wine at concentrations of up to 10 milligrams per litre. It serves as an antibiotic and antioxidant, protecting wine from spoilage by bacteria and oxidation. It also helps to keep volatile acidity at desirable levels. Sulfur dioxide is responsible for the words "contains sulfites" found on wine labels. Wines with SO2 concentrations below 10 ppm do not require "contains sulfites" on the label by US and EU laws. The upper limit of SO2 allowed in wine in the US is 350 ppm; in the EU it is 160 ppm for red wines and 210 ppm for white and rosť wines. In low concentrations SO2 is mostly undetectable in wine, but at over 50ppm, SO2becomes evident in the nose and taste of wine.
SO2 is also a very important element in winery sanitation. Wineries and equipment must be kept clean, and because bleach cannot be used in a winery, a mixture of SO2, water, and citric acid is commonly used to clean and sanitize equipment. Compounds of ozone (O3) are now used extensively as cleaning products in wineries due to their efficiency, and because these compounds do not affect the wine or equipment.
As a reducing agent Sulfur dioxide is also a good reductant. In the presence of water, sulfur dioxide is able to decolorize substances. Specifically it is a useful reducing bleach for papers and delicate materials such as clothes. This bleaching effect normally does not last very long. Oxygen in the atmosphere reoxidizes the reduced dyes, restoring the color. In municipal wastewater treatment sulfur dioxide is used to treat chlorinated wastewater prior to release. Sulfur dioxide reduces free and combined chlorine to chloride.
Recently many glass manufactures are using SO2 to treat their products. Treating the glass surfaces with acid gases such as S02 improve the chemcal resistance of glass.This is a tecnical and economically prospective solution.
Biochemical and biomedical roles
Sulfur dioxide is toxic in large amounts. It or its conjugate base bisulfite is produced biologically as an intermediate in both sulfate-reducing organisms and in sulfur oxidizing bacteria as well. Sulfur dioxide has no role in mammalian biology. Sulfur dioxide blocks nerve signals from the pulmonary stretch receptors (PSR's) and abolishes the Hering-Breuer inflation reflex.
As a refrigerant
Being easily condensed and possessing a high heat of evaporation, sulfur dioxide is a candidate material for refrigerants. Prior to the development of freons, sulfur dioxide was used as a refrigerant in home refrigerators.
As a reagent and solvent in the laboratory
Sulfur dioxide is a versatile inert solvent that has been widely used for dissolving highly oxidizing salts. It is also used occasionally as a source of the sulfonyl group in organic synthesis. Treatment of aryl diazonium salts with sulfur dioxide and cuprous chloride affords the corresponding aryl sulfonyl chloride.