Production and Uses of Chelating Agents

Overall market growth is mature and heavily dependent on the economy and environmental regulations. In the US, growth from 1998 to 2003 was expected to be about 2% per year250. 

EDTA is used in the separation of the rare earth elements. EDTA complexes have a stability that varies slightly from the rare earth elements. This slight variation allows EDTA to effectively separate rare-earth ions. EDTA is used as an anti-coagulant in blood. It prevents coagulation by sequestering the calcium ions required for clotting251. 

The sodium salt of EDTA is the primary product of the aminopolycarboxylic chelants. In 1998 it accounted for over 75% of the total chelant demand in the US, Western Europe and Japan250. 

DTPA tends to be a weaker chelator than EDTA. However it is very stable and has been found to be especially useful in peroxide bleach systems. DTPA works in a pH range similar to that of EDTA for most ions, but tends to have a slightly higher active range in controlling ferrous ions250. 

HEDTA was developed specifically for chelating ferric ions in alkaline systems. It chelates with maximum effectiveness in a pH range of 6 to 12. This prevents precipitation of iron compounds (e.g., ferric hydroxide and oxide) in this alkaline range. It is not as effective as EDTA for calcium and magnesium ions. It also tends to be less stable250. 

---