Basic Information

Other Names: 1-Hydroxy Ethylene-1,1-Diphosphonic Acid                

Molecular Formula:  C2H8O7 P 2    

Molecular Weight: 206.02

CAS NO.: 2809-21-4

UN NO.:3261

EINECS NO.: 220-552-8

Purity: 99.8% min.

Physicochemical Properties

1.Appearence: White crystalline powder

2.PH : 1.0-3.0  (10g/l @25℃)

3.Flammability (solid, gas):non flammable

4.Density: 1.0 - 1.1g/cm3 (bulk density)

5.Particle size:: 0.5-1.0mm

Technical Specifications

Name of IndexIndex
AppearanceWhite Crystal Powder
Active Content( as HEDP)%90.0 Min.
Active Content( as HEDP·H2O)%98.0 Min.
Phosphorous Acid (as PO33-)%0.8 Max.
Phosphorous Acid (as PO43-)%0.5 Max.
PH (1% solution)2.0 Max.
Chlorides (as CL-) ppm100 Max.
Iron ppm10 Max.

Packaging Types

   HEDP liquid: Normally In 30kg or 250kg net Plastic Drum;

      HEDP solid: 25kg inner liner polyethylene (PE) bag, outer plastic woven bag, or confirmed by clients request


HEDP is an organophosphoric acid corrosion inhibitor. It can chelate with Fe, Cu, and Zn etc. metal ions and form stable complex compound. It can dissolve the oxidized materials on these metals’ surfaces. Under 250℃ HEDP shows excellent scale and corrosion inhibition ability. 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 of HEDP is high purity product, suitable for using in winter and freezing districts. it is quite suitable for using as cleaning agent in electronic fields and as additives in daily chemicals.

Transport Information

ADR/RID Class: 8

Packing Group: III

Storage: Storage for ten months in room shady and dry place.