Soda lime

Soda lime is a mixture of chemicals, used in granular form in closed breathing environments, such as general anesthesia, submarines, rebreathers and recompression chambers, to remove carbon dioxide from breathing gases to prevent CO2 retention and carbon dioxide poisoning.

Composition

Soda lime is made by treating calcium hydroxide with sodium hydroxide. This results in a strong alkali that is capable of absorbing and neutralizing carbon dioxide. The primary components of soda lime are:

• Calcium hydroxide, Ca(OH)2 (about 75%)
• Water, H2O (about 20%)
• Sodium hydroxide, NaOH (about 3%)
• Potassium hydroxide, KOH (about 1%)

Uses

The main application of soda lime is in the absorption of carbon dioxide in breathing apparatus. In this context, it is also known as a carbon dioxide scrubber. The soda lime absorbs the carbon dioxide, allowing oxygen and other gases to be breathed. The reaction is exothermic, releasing heat and helping to warm the breathing gas.

Soda lime is also used in the petroleum industry, where it is used to remove acidic components from hydrocarbon gases. This helps to prevent corrosion in pipelines and processing equipment.

Safety

While soda lime is generally safe to handle, it can cause burns if it comes into contact with the skin or eyes. It is also harmful if swallowed. In a medical setting, soda lime canisters should be changed regularly to ensure they are effectively absorbing carbon dioxide.

See also

• Carbon dioxide scrubber
• Calcium hydroxide
• Sodium hydroxide
• Potassium hydroxide