CAS 2809-21-4 HEDP 1-Hydroxyethylidene-1,1-diphosphonic acid

CAS 2809-21-4 HEDP 1-Hydroxyethylidene-1,1-diphosphonic acid

Index	HEDP 60%	HEDP 90%
Appearance	Clear, Colorless to pale yellow aqueous solution	White crystal powder
Active content (HEDP) by wt %	58.0-62.0	90.0 min
Active content (HEDP·H2O) by wt %	-	98.0 min
Phosphorous acid (as PO3 3-) by wt %	2.0 max	0.8 max
Phosphoric acid (as PO4 3-) by wt %	0.8 max	0.5 max
Chloride (as Cl-) by wt %	0.02 max	0.01 max
pH (1% water solution)	2.0 max	2.0 max
Density (20ºC) g/cm3	1.40 min	-
Fe by mg/L	20.0 max	10.0 max
Ca sequestration by mg CaCO3/g	500.0 min	-

HEDP 60%: clear, colorless to pale yellow aqueous solution
HEDP 90%: white crystal powder

1. 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 250ºC. 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.

2. 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.

3.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.