EDTA, also known as ethylenediaminetetraacetic acid, is an organic compound with the formula C10H16N2O8. This white, water-soluble solid is used to form soluble complexes in aqueous solutions by binding to iron (Fe2+/Fe3+) and calcium (Ca2+) ions. In this way, it dissolves Fe- and Ca-containing scales and prevents the oxidation of iron ions. EDTA is available in several salt forms, particularly disodium EDTA, sodium calcium edetate, and tetrasodium EDTA, all of which function similarly.
The chemical and physical properties of EDTA are as follows:
- Molecular Weight: 292.24 g/mol
- Melting Point: 240 °C
- Density: 0.86 g/cm³ (at 20 °C)
- pKa Values: 2.0, 2.7, 6.16, 10.26
The production method of EDTA is as follows:
- Mannich-Type Reaction Method: This is the most common production method for EDTA. EDTA is obtained through a Mannich-type reaction involving ammonia, formaldehyde, and phosphoric acid. This reaction is similar to the Kabachnik–Fields reaction.
Applications of EDTA include:
- Textile and Paper Industries: In industry, EDTA is primarily used to bind metal ions in aqueous solutions. In the textile industry, it prevents metal ion contaminants from altering the colors of dyed products. In the paper industry, EDTA inhibits metal ions, particularly Mn2+, from catalyzing the decomposition of hydrogen peroxide, which is used in chlorine-free bleaching.
- Food Additive: EDTA is also used as a food additive. It is known by the code E385 and serves as a color preservative, antioxidant, and stabilizer. It can be found in canned vegetables, fruit juices, mayonnaise, margarine, and meat products.
- Cosmetics: EDTA is used in cosmetic products such as shampoo, soap, lotion, and toothpaste to prevent lime buildup and extend product shelf life.
- Medicine: In medicine, EDTA is used as an anticoagulant to prevent blood samples from clotting. It is also used in the treatment of heavy metal poisoning