Sulfur dioxide (Sulfur Dioxide; chemical formula: SO2) is a colorless gas at room temperature with a pungent odor. Easily soluble in water, its aqueous solution is called sulfurous acid. Most people can smell sulfur dioxide at concentrations of 0.3 to 1 ppm. It is handled and transported as a liquefied compressed gas.
Sulfur dioxide is produced through a variety of natural and human activities, including volcanic eruptions, industrial processes and the burning of sulfur-containing fossil fuels.
Food related uses
Food industry preservatives
Sulfur dioxide is used as a preservative in the food industry, especially in dried fruits, wine and certain processed foods. It helps prevent microbial growth and oxidation and preserves product color and flavor.
This compound was first used in food products starting in the 1970s. However, in 1986 the U.S. Food and Drug Administration banned its use in fresh fruits and vegetables .
If a package of dried fruit lists sulfur dioxide, it may also say "for freshness" in parentheses , which leads consumers to believe the preservatives are safe to eat.
Consumers are unaware of the impact sulfur dioxide has on consumer health. The good news is that the U.S. Food and Drug Administration requires food labels to label foods containing more than 10 parts per million of sulfites. However, sulfur dioxide uses are not visible to consumers because they fall within this threshold. Manufacturers can soak the fruit in sulfur dioxide and boil it long enough during the production process to meet the FDA's requirement of less than 10 parts per million of sulfur dioxide.
Sulfur dioxide and its salts have been added to the winemaking process since the 17th century. Sulfur dioxide plays a vital role in the winemaking process. Adding it to wine prevents oxidation, inhibits the growth of undesirable microorganisms, and maintains the quality of the wine.
Are drinks containing sulfur dioxide safe to drink?
Most people can safely consume sulfites in wine with minimal risk of adverse side effects.
Even high dilutions can induce asthma when inhaled or ingested by sensitive subjects. About one in nine asthmatics have a history of asthma exacerbation by drinking "soft drinks" containing sulfur dioxide.
Sulfur dioxide is used as a bleaching agent in the paper and textile industries. It helps remove color from certain substances.
It is a precursor in the synthesis of various chemicals, including sulfuric acid (H2SO4) and other sulfur-containing compounds.
Sulfur dioxide is used in water treatment processes to eliminate excess chlorine that may be present after chlorination.
In the pharmaceutical industry, sulfur dioxide is used in the synthesis of certain drugs.
In the laboratory, sulfur dioxide is used for a variety of purposes, such as as a reducing agent in chemical reactions.
air pollution control
Sulfur dioxide emitted during industrial production causes air pollution. We strive to control these emissions to mitigate environmental and health impacts.
Historically, sulfur dioxide was used as a refrigerant in some older refrigeration systems. However, due to its potential environmental impact, its use has largely been phased out in favor of more environmentally friendly alternatives.
It's worth noting that while sulfur dioxide has a variety of industrial uses, its release into the atmosphere, especially when fossil fuels are burned, can contribute to air pollution and the formation of acid rain. Many regions have enacted strict regulations and emission control measures to address environmental issues related to sulfur dioxide emissions.
Air conditioning and cooling
Sulfur dioxide is used in refrigeration and cooling systems in the form of dry ice (solid carbon dioxide). It can sublime, changing directly from a solid to a gas, which makes it useful for maintaining low temperatures.