1-Hydroxyethylidene-1, 1-Diphosphonic Acid


CAS No.: 2809-21-4
Other Name: HEDPA
Molecular Formula: C2H8O7P2
Molecular Weight: 206.02

HEDP is an organic phosphoric acid corrosion inhibitor. It can chelate with Fe, Cu, and Zn ions to form stable chelating compounds. It can dissolve the oxidized materials on the surfaces of these metals. HEDP shows excellent scale and corrosion inhibition effects even under temperature 250℃. HEDP has good chemical stability at high pH value. It is hard to hydrolyze and to decompose under ordinary light and heat conditions. It has acid resistance, base resistance and it resists oxidation by chloride. These three performances are better than other organic phosphoric acids (salts). HEDP can react with metal ions calcium ion in water to form hexa-element chelating complex, with in particular. Therefore, HEDP has good antiscale effect and obvious threshold effect. When built together with other water treatment chemicals, it shows good synergistic effects.

The solid state of HEDP is crystal powder, it is suitable to use in winter and in freezing districts. Because of its high purity, it can be used as cleaning agent in electronic fields and as additives in daily chemicals.

Items Index
Appearance Colorless or pale yellow transparent aqueous solution White crystal powder
Active content (HEDP)% 58.0-62.0 90.0min
Phosphorous acid (PO3 3-) % 1.0 max 0.8 max
Phosphoric acid (PO4 3- )% 0.6 max 0.5 max
Chloride ( Cl - ) ppm 100.0 max 100.0max
pH (1% aqueous solution) 2.0 max 2.0 max
Density (20 ℃ )g/cm3 1.43-1.47 -
Fe, mg/L 10.0 max 5.0 max
Acetic acid % 0.5 max
Ca sequestration (mg CaCO3 /g) 500.0 min

HEDP is used as scale and corrosion inhibition in circulating cooling water systems, low-pressure boilers, oil field water injection, and oil pipelines in the fields such as electric power, chemical industry, metallurgy, fertilizer, etc. In light textile 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 industry, 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.

Package and Storage:
HEDP liquid: Normally in 250kg net plastic drum, IBC drum can also be used as required
HEDP solid: 25kginner liner polyethylene (PE) bag, outer plastic woven bag, or confirmed by clients.
Storage for ten months in room in shady and dry places.

Safety Protection:
Acidic. Avoid contact with eye and skin. In case of contact, rinse immediately with plenty of clean water.

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