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Etidronic Acid (HEDP)


Synonyms: Hydroxyethylidenedi(phosphonic acid); Etidronic acid; HEDP

Molecular Formula:C2H8O7P2
Molecular Weight: 206.03
CAS Number: 2809-21-4
EINECS Number: 2205528


Appearance: water white to pale yellow liquid

Density: 1.28-1.38 g/ml at 20 °C
Solubility in water:miscible
Stability: stable under ordinary conditions


Test Items
Water white to pale yellow liquid  
Active acid
58.0 – 62.0%
pH (1% solution) @ 25 ℃
2.0 max
Density @20 ℃
1.42 – 1.47g/cm3 
Chloride (as Cl)
100ppm max
Iron (as Fe)
20ppm max
H3PO4 (as PO4)
4.0% max
Color (APHA, Hazen)
150 max


Storage and Packing

Packing: 250kgs net in PE drum, 1250kgs net in IBC or Isotank



HEDP is noted for excellent CACO3 scale inhibition and chlorine stability. It is widely used in industry as a sequestering agent and calcium carbonate scale inhibitor for applications in cooling water treatment, boiler water treatment, industrial and institutional cleaners, swimming pool stain prevention, personal care products, metal ion control.

Safety Infromation

UN 3265 8/PG 3