Nitrilotriacetic acid
Encyclopedia
Nitrilotriacetic acid C6H9NO6, is a polyamino carboxylic acid
Polyamino carboxylic acid
thumb|left|120px|a metal complex with the [[EDTA]] anionthumb|120px|the [[glycine|glycinate]] ion can form a chelate complex with a metal ionthumb|120px| β [[alanine]]...

 and is used as a chelating agent which forms coordination compounds with metal ions (chelates) such as Ca2+, Cu2+ or Fe3+.

The uses of NTA are similar to that of EDTA
EDTA
Ethylenediaminetetraacetic acid, widely abbreviated as EDTA , is a polyamino carboxylic acid and a colourless, water-soluble solid. Its conjugate base is named ethylenediaminetetraacetate. It is widely used to dissolve limescale. Its usefulness arises because of its role as a hexadentate ligand...

. However, in contrast to EDTA, NTA is easily biodegradable and is almost completely removed during wastewater treatment.

Production

This compound is commercially available as the free acid and the sodium salt. It is produced from ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

, formaldehyde
Formaldehyde
Formaldehyde is an organic compound with the formula CH2O. It is the simplest aldehyde, hence its systematic name methanal.Formaldehyde is a colorless gas with a characteristic pungent odor. It is an important precursor to many other chemical compounds, especially for polymers...

, and sodium cyanide
Sodium cyanide
Sodium cyanide is an inorganic compound with the formula NaCN. This highly toxic colorless salt is used mainly in gold mining but has other niche applications...

 or hydrogen cyanide. Worldwide capacity is estimated at 100 thousand tonnes per year.

Uses

Nitrilotriacetic acid is a chelating agent. It is used for water softening
Water softening
Water softening is the reduction of the concentration of calcium, magnesium, and certain other metal cations in hard water. These "hardness ions" can cause a variety of undesired effects including interfering with the action of soaps, the build up of limescale, which can foul plumbing, and...

 and as a replacement to sodium triphosphate in detergents, and potassium triphosphate in cleansers.

In the laboratory, this compound may be used in complexometric titrations. A variant of NTA is used for protein isolation and purification in the His-tag method. The modified NTA is used to immobilize nickel to a solid support. This allows separation of proteins containing "tag" containing six histidine residues at the C-terminus.

Biodegradation

Nitrilotriacetic acid is easily biodegraded; 98 % is removed in biological wastewater treatment plant
Wastewater treatment plant
Wastewater treatment plant also called wastewater treatment works can mean one of the following:*Sewage treatment – treatment and disposal of human waste....

s.
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