HEDP Na4(Sodium Salt of 1-Hydroxy Ethylidene-1,1-Diphosphonic Acid) 


CAS No.  29329-71-3 (x-Na), 3794-83-0 (4-Na)   

Synonyms: Tetrasodium etidronate, HEDP 4Na, Tetrasodium (1-hydroxyethylidene)bisphosphonate

Molecular Formula: C2H4O7P2Na                   

Molecular weight: 294

Structural Formula:


HEDP•Na4  (similar to Request 2016) is the sodium salt of HEDP, HEDP•Na4 is a good scale inhibitor for calcium carbonate, it can be used in low-pressure boiler water systems, circulating water systems, industrial and municipal cleaning water systems, and swimming pools.

The solid HEDP•Na4 is a white powder, soluble in water, easily deliquescence, and suitable for use in winter and freezing districts. It is a kind of organophorphonic acid scale and corrosion inhibitor, can form stable complexes with Fe, Cu, and Zn ions, it can dissolve the oxides on the metal surface, it has a good scale and corrosion inhibition effect under 250℃.

HEDP•Na4 is widely used in circulating cool water systems, medium and low-pressure boilers, and oil field water pipelines as a scale and corrosion inhibitor in fields such as electric power, chemical industry, metallurgy, fertilizer, etc. In the light woven industry, HEDP•Na4 is used as a detergent for metal and nonmetal. In the dyeing industry, HEDP•Na4 is used as a peroxide stabilizer and dye-fixing agent; In non-cyanide electroplating, HEDP•Na4 is used as a chelating agent.


AppearanceColorless to yellowish transparent liquid
Active content (HEDP)%20.3-21.7
Active content (HEDP•Na4)%29.0-31.0
Total phosphoric acid (as PO43-) %18.4-20.4
Fe, mg/L20.0 max
Density (20℃)g/cm31.26-1.36
PH (1% water solution)10.0-12.0


Package and Storage:

200L plastic drum, IBC(1000L),customers’ requirement. Storage for ten months in a shady room and dry place.

Safety Protection:

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



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