Corrosion inhibitor - Dispersant - Scale and corrosion inhibitor

1-Hydroxy Ethylidene-1,1-Diphosphonic Acid ( HEDP )

CAS No. 2809-21-4

Molecular Formula: C2H8O7P2 Molecular weight: 206.02

Structural Formula:



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 250℃. 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 ofHEDP 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      Clear, Colorless to pale yellow aqueous solutionWhite crystal powder
Active content (HEDP), %      58-62      90.0 min
Active content (HEDP·H2O), %      -      98.0 min
Phosphorous acid (as PO33-), %2.0 max0.8 max
Phosphoric acid (as PO43-), %0.8 max0.5 max
Chloride (as Cl-), ppm100.0 max      100.0max
pH (1% water solution)2.0 max2.0 max
Density (20℃), g/cm31.43-1.47-
Fe, mg/L20.0 max10.0 max
Color APHA (Hazen)40.0 max-
Ca Sequestration (mg CaCO3/g)500.0 min


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, fertilizer, etc.. In light woven industry,HEDP is used as detergent for metal and nonmetal. In dyeing industry, HEDP is used as peroxide stabilizer and dye-fixing agent; In non-cyanide electroplating,HEDP is used as chelating agent. The dosage of 1-10mg/L is preferred as scale inhibitor, 10-50mg/L as corrosion inhibitor, and 1000-2000mg/L as detergent. Usually,HEDP is used together with polycarboxylic acid.

Package and Storage:

HEDP liquid: 200L plastic drum,IBC(1000L),customers’ requirement.

HEDP solid: 25kg/bag,customers’ requirement.

Storage for ten months in room shady and dry place.

Safety Protection:

Acidity, Avoid contact with eye and skin, once contacted, flush with water. 

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