1-Hydroxy Ethylidene-1,1-Diphosphonic Acid (HEDP)
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HEDP is an organophosphoric acid corrosion inhibitor. It can chelate with Fe, Cu, and Zn ions to form stable chelating compounds. It can dissolve the oxidized materials on these metals surfaces. HEDP shows excellent scale and corrosion inhibition effects under temperature 2500. HEDP has good chemical stability under high pH value, hard to be hydrolyzed, and hard to be decomposed under ordinary light and heat conditions. Its acid/alkali and chlorine oxidation tolerance are better than that of other organophosphoric acids (salt) . HEDP can react with metal ions in water system to form hexa-element chelating complex, with calcium ion in particular. Therefore, HEDP has good antiscale and visible threshold effects. When built together with other water treatment chemicals, it shows good synergistic effects.
The solid state of HEDP is crystal powder, suitable for usage in winter and freezing districts. Because of its high purity, it can be used as cleaning agent in electronic fields and as additives in daily chemicals.
Appearance Colorless or light yellow transparent liquid White crystal powder
Active content (HEDP) % 58.0-62.0 89.0 min
Phosphorous acid (as PO33-) % 2.0 max 0.5 max
Phosphoric acid (asPO43- ) % 0.8 max 0.5 max
Chloride (as Cl-) % 0.01 max 0.01 max
pH (1% solution) 2 max 2 max
Density (200) g/cm3 1.40 -
Fe ion ppm 10 max 20 max
Colour APHA (Hazen) 40 max -
HEDP is used as scale and corrosion inhibition in circulating cool water system, oil field and low-pressure boilers in fields such as electric power, chemical industry, metallurgy,