Calcium hydroxide, also known as slaked lime or hydrated lime, is formed by mixing calcium oxide with water. Calcium hydroxide is a white, powdery solid that is strongly alkaline. Industries that use calcium hydroxide include dentistry, food storage and shipping, and various types of manufacturing, where it treats industrial waste. The U.S. Centers for Disease Control reports that ingesting, inhaling or getting calcium hydroxide on your skin can result in irritation or even chemical burns.
Dentistry
Calcium hydroxide is often used in dentistry, according to the National Center for Biotechnology Information. Among its purposes, calcium hydroxide treats damaged teeth, especially immature permanent teeth, to preserve the living tissue, or "pulp," at the center of the tooth. It is also used as an antibiotic during root canals, although evidence suggests it is not particularly effective at killing bacteria, reports a 2007 article published in Evidence-Based Dentistry.
Food Storage and Shipping
The food shipping and storage industries use calcium hydroxide, according to the Clean Washington Center. In these industries, it keeps fruit from ripening before it can be shipped to grocery stores across the country. During the storage process, the calcium hydroxide gradually turns to calcium carbonate as it picks up carbon dioxide molecules from the air. Some industries have begun recycling this calcium carbonate and using it in manufacturing and other processes.
Manufacturing
Manufacturing processes employ calcium hydroxide for a number of different products, according to Peters Chemical. For example, calcium hydroxide is used in iron refining, where it is mixed with melted iron ore to separate silicate compounds out of the mixture, leaving the iron behind. In paper manufacturing, it is one chemical within the bleaching process that makes paper white. It is even part of paper recycling, as a coagulant to help remove ink and dyes from waste paper before it is recycled into new paper.
References
- Centers for Disease Control: NIOSH Guide to Calcium Hydroxide
- National Center for Biotechnology Information: Use of calcium hydroxide for apical barrier formation and healing in non-vital immature permanent teeth: a review.
- Evidence-Based Dentistry: Calcium hydroxide has limited effectiveness in eliminating bacteria from human root canal
- Clean Washington Center: Beneficial Use of Spent Calcium Hydroxide from Fruit Cold Storage Warehouses
- Peters Chemical Company: Calcium Hydroxide
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