Etidronic acid HEDP CAS 2809-21-4, also called 1-Hydroxyethylidene-1,1-diphosphonic acid, 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 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.
Specification of HEDP
HEDP 58%-62% liquid
Appearance Colorless to pale yellow aqueous solution
Active content (HEDP)% 58.0-62.0
Phosphorous acid (as PO33-)% 1.0 max
Phosphoric acid (asPO43- )% 0.6 max
Chloride (as Cl-) ppm 100.0 max
pH (1% solution) 2.0 max
Density g/cm3 1.43-1.47
Fe,mg/L 10.0 max
Colour APHA (Hazen) 30.0 max
Ca sequestration (mg CaCO3/g) 500.0 min
HEDP 98% solidAppearance White crystal powder
Active content(HEDP)% 90.0 min
Active content (HEDP H2O)% 98.0 min
Phosphorous acid (as PO33-)% 0.8 max
Phosphoric acid (asPO43- )% 0.5 max
Chloride (as Cl-) ppm 100.0max
pH (1% solution) 2.0 max
Fe,mg/L 5.0 max
Application of HEDP
HEDP is used as scale and corrosion inhibition in circulating cool water system, oil field and low pressure boilers in fieldssuch as electric power, chemical industry, metallurgy, fertilizer, etc..
1) In light woven industry, HEDP is used as detergent for metal and nonmetal.
2) In dyeing industry, HEDP is used as peroxide stabilizer and dye-fixing agent;
3) In non-cyanide electroplating, HEDP is used as chelating agent. The dosage of 110mg/L is preferred as scale inhibitor,
10-50mg/L as corrosion inhibitor, and 1000-2000mg/L as detergent.
4) HEDP is usually used together with polycarboxylic acid.
5) HEDP is listed as an ingredient of several cosmetic formulations where it is used for suppressing radical formation, emulsion stabiliser and viscosity control.
Solid: 25kg per bag,25mt per 20ft container
Liquid: 250kg per drum,80drums per 20ft container
Storage & Transport
Stored in cool and airy place; away from fire and heat; handle with care; no breakage, avoid leakage.It is valid for 1 years under proper condition.
HEDP is classified as Dangerous Good for transport (UN 3261,Class 8,Packing group III)
Please refer to MSDS for more information about Safety,Storage and Transportation.