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

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

 

 

CAS No.                                                        : 2809-21-4

Molecular Formula                                      : C2H8O7P2                

Molecular weight                                         : 206.02

 

Physical and Chemical Properties

items

index

Appearance

Colorless or light yellow transparent liquid

White crystal powder

Active content (HEDP)%

58.0-62.0

90.0min

Phosphorous acid (as PO33-)%

2.0 max

0.8 max

Phosphoric acid  (asPO43- )%

0.8 max

0.5 max

Chloride (as Cl-)%

1.0 max

0.1max

pH (1％ solution)

2 max

2 max

Density  (20℃)g/cm3

1.40

-

Fe ion ppm

10 max

5 max

Colour APHA (Hazen)

40 max

-

Properties:

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 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. 

 Usage:

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.