In industry, EDTA is mainly used to sequester metal ions in aqueous solution. In the textile industry , it prevents metal ion impurities from modifying colours of dyed products. In the pulp and paper industry , EDTA inhibits the ability of metal ions, especially Mn 2+ , from catalysing the disproportionation of hydrogen peroxide , which is used in chlorine-free bleaching . In a similar manner, EDTA is added to some food as a preservative or stabiliser to prevent catalytic oxidative decolouration, which is catalysed by metal ions. [5] In soft drinks containing ascorbic acid and sodium benzoate , EDTA mitigates formation of benzene (a carcinogen ). [6]
The reduction of water hardness in laundry applications and the dissolution of scale in boilers both rely on EDTA and related
complexants
to bind
Ca
2+
,
Mg
2+
, as well as other metal ions. Once bound to EDTA, these metal complexes are less likely to form precipitates or to interfere with the action of the
soaps
and
detergents
. For similar reasons, cleaning solutions often contain EDTA. In a similar manner EDTA is used in the cement industry for the determination of
free lime
and free
magnesia
in cement and
clinkers