SO2 and corrosion

Sulfur dioxide

Sulfur dioxide (chemical formula SO2) is a colorless gas with a strong, pungent odor. It is highly reactive and is capable of combining with other compounds to form toxic products such as sulfuric acid and sulfurous acid. The vast majority (close to 99%) of sulfur dioxide originates from human activity, specifically, industrial activities that process materials containing sulfur. Sulfur dioxide can contribute to the corrosion process.

video: Tripod corrosion on the vulcan
Source: James Cooper (Instagram @pitonrescue)
Sulfur dioxide and corrosion

Sulfur dioxide is known for its aggressiveness towards steel and other metal alloys. While the compound in its pure form does not react strongly with metal, it can be highly corrosive when exposed to the atmosphere. When sulfur dioxide reacts with moisture (water) and oxygen, sulfuric acid is formed.

This acidic compound is highly corrosive and can result in the accelerated deterioration of steel infrastructures. The sulfate ions formed on the surface of the moisture layer is considered to be the main contributor to accelerated corrosion on metallic surfaces.

Where you can meet SO2

Sulphur dioxide (SO2) is one of the most common gases released in volcanic eruptions (following water and carbon dioxide) and is of concern on the global scale due to its potential to influence climate. On the local scale SO2 is a hazard to humans in its gaseous form and also because it oxidises to form sulphate aerosol.

Sulfur dioxide is used in many industries. It’s used to manufacture sulfuric acid, paper, and food preservatives. Some examples of workers at risk of being exposed to sulfur dioxide include the following: Factory workers in industries where it occurs as a by-product, such as copper smelting or power plants.

The main sources of sulfur dioxide emissions are from fossil fuel combustion and natural volcanic activity. Some industrial areas have high level of sulfur dioxide in the air.

Materials for this article were gathered from various public sources or written by editors.
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