HEDP 50% 60% 90% 98%
CAS No.: 2809-21-4 EINECS No.: 220-552-8
Molecular Formula: C2H8O7P2 Molecular Weight: 206.02
RIDADR: UN 3265 8/PG III
HEDP is a kind of scale and corrosion inhibitor which belongs to organic phosphonic acid. It can form stable complexes with iron, copper, zinc and other metal ions, and can also dissolve the metal surface oxide. Under 250 ℃ condition, HEDP can still play a good corrosion and scale inhibition effect.
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 show better than that of other organic phosphonic acid (salt) acids (salt).
HEDP can react with metal ions in water system to form hexa-element chelating complex, especially with calcium ions. Therefore, HEDP has good anti-scale and visible threshold effects. When used in combination with other water treatment chemicals, it shows ideal synergistic effects.
HEDP solid state is a high purity product, suitable for cold winter areas; Because of its high purity, it is especially used as the cleaning agents in electronics industry, and additives in daily chemicals.
HEDP is widely used as scale and corrosion inhibitor in industrial circulating cooling water systems of electric power, chemical industry, metallurgy, chemical fertilizer, and also in medium or low pressure boilers, oilfield water injection and oil pipeline.
Besides these applications, HEDP can also be used as cleaning agent of metal and nonmetal in the textile industry, as peroxide stabilizer and fixing agent in bleaching and dyeing industry, as complexing agent in cyanide free electroplating industry, as the carrier of radioactive elements in pharmaceutical industry, and so on.
|Appearance||Clear, Colorless to pale yellow aqueous solution||White crystal powder|
|Active content (HEDP)%||60.0 min||90.0 min|
|Active content (HEDP·H2O)%||–||98.0 min|
|Phosphorous acid (as PO33-)%||1.0 max||0.8 max|
|Phosphoric acid (as PO43- )%||0.6 max||0.5 max|
|Chloride (as Cl–)%||0.01 max||0.01 max|
|pH (1% water solution)||2.0 max||2.0 max|
|Density (20℃)g/cm3||1.40 min||–|
|Fe, mg/L||10.0 max||5.0 max|
|Colour APHA (Hazen)||10.0 max||–|
|Ca sequestration (mg CaCO3/g)||500.0 min||–|
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.
HEDP; HEDP(A); HEDPA; Etidronic Acid;
1-Hydroxy Ethylidene-1,1-Diphosphonic Acid;
Hydroxyethylidene Diphosphonic Acid (HEDP);
Oxyethylidenediphosphonic Acid (OEDP);
Phosphonates Antiscalants, Corrosion Inhibitors and Chelating Agents
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