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

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

1-Hydroxy Ethylidene-1,1-Diphosphonic Acid is an organophosphorus 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. Keywords:1-Hydroxy Ethylidene-1,1-Diphosphonic Acid, China, Suppliers, Manufacturers, Factory, Wholesale, Price

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Product Description

HEDP | Etidronic acid | 1-Hydroxy Ethylidene-1,1-Diphosphonic Acid | hedp 60% -vcycletech

Chinese name 羟基乙叉二膦酸 Molecular formula C2H8O7P2
Foreign Name Etidronic acid Molecular weight 206.03
Alias Ethane-1-hydroxy-1,1-diphosphoric acid External view Colourless to pale yellow liquid
CAS NO. 2809-21-4 Density 1.45 (60% aq.)
EINECS 220-552-8 Melting point 198~199℃

Molecular formula: HEDP Molecular formula

1-Hydroxy Ethylidene-1,1-Diphosphonic Acid & Properties

HEDP is an organophosphorus 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 the 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. It's acid/alkali and chlorine oxidation tolerance is better than that of other organophosphorus acids (salt). HEDP can react with metal ions in the water system to form a 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. Its high purity can be used as a cleaning agent in electronic fields and as additives in daily chemicals.

Related products you may be interested in HEDP Na2HEDP Na4

1-Hydroxy Ethylidene-1,1-Diphosphonic Acid & Specification




Clear, Colorless to pale yellow aqueous solution

White crystal powder

Active content (HEDP)%



Phosphorous acid (as PO33-)%

1.0 max

0.8 max

Phosphoric acid (asPO43-)%

0.6 max

0.5 max

Chloride (as Cl-) ppm

100.0 max


pH (1% solution)

2.0 max

2.0 max

Density (20℃)g/cm3




10.0 max

5.0 max

Colour APHA (Hazen)

30.0 max


Acetic acid %

0.5 max


Ca sequestration (mg CaCO3/g)

500.0 min


1-Hydroxy Ethylidene-1,1-Diphosphonic Acid | Product use

HEDP is used as scale and corrosion inhibition in circulating cool water systems, oil fields, and low-pressure boilers in electric power, chemical industry, metallurgy, fertilizer, etc. In the light woven industry, HEDP is used as detergent for metal and nonmetal. HEDP is used as a peroxide stabilizer and dye-fixing agent; In non-cyanide electroplating, HEDP is used as a chelating agent. The dosage of 1-10mg/L is preferred as a scale inhibitor, 10-50mg/L as a corrosion inhibitor, and 1000-2000mg/L as detergent. Usually, HEDP is used together with polycarboxylic acid.

{Application 1}It is a scale and corrosion inhibitor for boilers and heat exchangers, a complexing agent for non-cyanide plating, a chelating agent for soap, and a cleaning agent for metals and non-metals.

{Application 2}It is often used as a scale and corrosion inhibitor in the boiler water, circulating water, and oilfield water treatment. It is often compounded with polyhydroxy acid-type scale inhibitor and dispersant. It can also be used as a complexing agent for non-cyanide electroplating, a color fixing agent for the bleaching and dyeing industry, and a hydrogen peroxide stabilizer.

{Application 3}This product is the main material for cyanide-free electroplating. It can be used as the main material of cyanide-free electroplating, and it can be used as a solution for direct electroplating of copper on steel. The plating layer is smooth and of good color. The general dosage of 60% is 100-120 ml/L. The dosage of copper sulfate is 15-20 g/L. Besides, before plating, the plated parts are dipped in 1%-2% solution to make the plated parts become activated and then plated to improve the effect.

{Application 4}This product is a new type of non-chlorine plating complexing agent used as the main agent for water quality stabilization in circulating cooling water systems. It plays the role of corrosion and scale inhibition. This product is one of the organic polyphosphoric acid water tablets, domestic production of these products and other varieties, such as amino-trimethylene phosphonic acid (ATMP): [CH2PO (OH) 2]3N and ethylenediamine tetramethylene phosphonic acid (EDTMP) and so on. Organic polyphosphoric acids are a class of water treatment agents developed in the late '60s and identified around the '70s. The advent of these treatment agents has brought water sheet technology a significant step forward. Compared with organic polyphosphonates, organic polyphosphoric acid has good chemical stability, not easy to hydrolysis, can withstand higher temperatures and small dosage, and both corrosion and scale performance and other characteristics. It is a class of cathodic corrosion inhibitor and a class of non-chemical equivalent scale inhibitor. When used in combination with other water treatment agents, it shows the ideal synergistic effect. It has excellent chelating performance for many metal ions such as calcium, magnesium, copper, zinc, etc. It even has a good de-activating effect on inorganic salts of these metals such as CaSO4, CaCO3, MgSiO3, etc. Therefore, it is widely used in water treatment technology. The product is low in toxicity. The LD50 for subcutaneous injection in mice is 486.4mg/kg.

{Application 5} It is used as a scale inhibitor at a concentration of 1~10mg/L and as a corrosion inhibitor at a concentration of 10~50mg/L. It is used as a cleaning agent at a concentration of 1000~2000mg/L. It is usually used in combination with polycarboxylic acid-type scale inhibitors and dispersants.

{Application 6}In this paper, under the simulation of industrial boiler water quality, the determination method of HEDP in furnace water is optimized, the high-temperature dissociation characteristics of HEDP are studied, and the scale inhibition and corrosion inhibition properties of HEDP are studied, and the following conclusions are drawn. HEDP is used as a scale and corrosion inhibitor in boiler furnace water, the first problem that needs to be solved is the determination of HEDP. However, the HG/T3537-1999 standard method for analyzing and detecting HEDP is cumbersome (determination time generally takes 2-3 hours). Using thorium nitrate complex titration to detect HEDP, although the determination steps are simple, thorium nitrate is a radioactive substance that will bring a great burden to the environment and harmful to human beings. The determination of HEDP was investigated by an improved spectrophotometric method, and it greatly reduced the determination time (what could complete the determination within 20-30 minutes). Besides, the effect of various ions that may be present in industrial boilers' furnace water on the determination was investigated, and what determined the optimum conditions for the determination (wavelength 470 nm, pH less than 2, reaction time 5 minutes, color development time 15 minutes). The determination of HEDP was not interfered with when the NaCl content in the furnace water was less than 500 mg/L, and the Ca2+ concentration was less than 300 mg/L, the phosphate content was less than 20 mg/L, and the SO42- the content was within 50 mg/L. The method is simple, rapid, sensitive, and resistant to interference. The stability of HEDP in furnace water directly affects its scale and corrosion inhibition performance, so who studied the thermal decomposition characteristics of HEDP in simulated industrial boiler furnace water under aerobic and anaerobic as well as different pH conditions. When the temperature reaches 160°C, HEDP decomposes almost completely, and the decomposition products are mainly phosphate compounds. Under anaerobic conditions, the decomposition of HEDP also increases with increasing temperature, and a greater degree of decomposition of HEDP occurs above 200°C. However, compared to the decomposition pattern of HEDP under aerobic conditions, the temperature at which it can withstand is higher, thus indicating that to make the best use of HEDP, controlling the furnace water's oxygen content has a vital role to play. what investigated the effect of pH changes on the thermal decomposition of HEDP at 150°C. The experiments showed that pH changes have little effect on the thermal decomposition of HEDP and that HEDP can exist stably under highly alkaline conditions. The scale inhibition performance of HEDP was tested by conductivity and static scale inhibition experiments, which showed that the conductivity and static scale inhibition methods are consistent in evaluating the scale inhibition performance of HEDP. With the increase of HEDP concentration, the scale inhibition rate gradually increases. Still, the scale inhibition efficiency of HEDP is a certain threshold value, and the scale inhibition rate will not change greatly after increasing to a certain degree. The solution with 5-7mg/L HEDP can achieve a large scale inhibition rate; besides, its scale inhibition performance also has a greater relationship with the concentration of the solution and pH; the temperature has a greater impact on the scale inhibition performance of HEDP, as the temperature increases the scale inhibition performance of HEDP also decreases. Under low calcium ion concentration and HCO3- concentration, HEDP has a good inhibition effect on the calcium carbonate scale. High calcium ion concentration and HCO3- concentration will inhibit the scale inhibition performance of HEDP. The corrosion inhibition performance of HEDP on 20-gauge carbon steel at room temperature was investigated using the electrochemical AC impedance method, Tafel polarization curve method, and autoclave hanging experiments. The experiments showed that a certain concentration of HEDP (25 mg/L) could effectively inhibit the corrosion of carbon steel, and the electrochemical experiments and the high-temperature flake hanging experiments showed consistent results; the HEDP autoclave flake hanging experiments showed that the oxidation rate of 20-gauge carbon steel in the simulated furnace water was lower than the dissolution rate in the temperature range of industrial boiler operation, and the flakes showed weight loss. However, the addition of HEDP could not reduce the Cl -concentration in the furnace water. The addition of HEDP effectively inhibits the direct corrosion of metals by chloride ions, thus allowing for relatively high chloride ions in the furnace water. Through the test and analysis of various factors affecting the scale and corrosion inhibition performance of HEDP in the simulated furnace water, such as HEDP concentration, aggressive anions in the furnace water and temperature, the scale inhibition performance of HEDP, and what comprehensively evaluated corrosion inhibition performance of 20-gauge carbon steel. More suitable condition parameters were obtained, which can provide a reference for actual production.

1-Hydroxy Ethylidene-1,1-Diphosphonic Acid & Package and Storage

HEDP liquid: Normally, In 250kg net Plastic Drum, IBC drum can also be used as required

HEDP solid: 25kg inner liner polyethylene (PE) bag, outer plastic woven bag, or confirmed by clients.

Storage for ten months in room shady and dry place.

1-Hydroxy Ethylidene-1,1-Diphosphonic Acid & Safety Protection

Acidity, Avoid contact with eye and skin, once contacted, flush with water.

1-Hydroxy Ethylidene-1,1-Diphosphonic Acid - Synonyms


Etidronic Acid;

1-Hydroxy Ethylidene-1,1-Diphosphonic Acid;


1-Hydroxyethylidenediphosphonic Acid;

Hydroxyethylidene Diphosphonic acid(HEDP);

1-Hydroxy-1,1-Ethanediyl ester;

Oxyethylidenediphosphonic Acid(OEDP)

Оксиэтилидендифосфоновая кислота(ОЭДФ -кислота )

1-Hydroxy Ethylidene-1,1-Diphosphonic Acid & FAQ

Material Safety Data Sheet for Hydroxyethylenediphosphonic Acid
HEDP Phosphate SDS Safety Data Sheet (Safety Data Sheet)

Hydroxyethylenebisphosphonic Acid (HEDP Phosphate) SDS, Safety Data Sheet.
MSDS sheet, Material Safety Data Sheet

1-Hydroxy Ethylidene-1,1-Diphosphonic Acid & Product Identification

Product Name / Synonyms. Hydroxyethylenebisphosphonic acid; Sal HEDP Phosphonate; HEDP(A); HEDPA; ETIDRONIC ACID; 1-Hydroxyethylidene-1,1-diphosphonic acid. 1-Hydroxyethylidene-1,1-diphosphonic acid (HEDP); 1-Hydroxyethylidene-1,1-diphosphonic acid (HEDP); 1-Hydroxy-1,1-ethanediyl ester
CAS No.: 2809-21-4
EINECS Number: 220-552-8
Molecular weight: 206.02
Chemical formula: C2H8O7P2 C2H8O7P2
Suggested Use and Suggested Prohibited Use (if any) Oil and gas well fracturing and industrial manufacturing.

1-Hydroxy Ethylidene-1,1-Diphosphonic Acid & Hazard Identification

GHS, Globally Harmonized System Classification following 29 CFR 1910.
Classification following Regulation (EC) No. 1272/2008.

Corrosive to metals Category 1
Acute toxicity. Oral, Category 4
Skin corrosion/irritation, Class 1A Class B Class C
Hazardous to the aquatic environment, Category 2 Acute hazard.

They are labeled following US GHS and Regulation (EC) No 1272/2008.

GHS labeling elements
Signal word. Hazard

1-Hydroxy Ethylidene-1,1-Diphosphonic Acid & Hazard statement.

H290: May be corrosive to metals.
H302: Harmful if swallowed.
H314: Can cause severe skin burns and eye damage.
H401: Toxic to aquatic organisms.

1-Hydroxy Ethylidene-1,1-Diphosphonic Acid & Precautionary statements.

P234: Store only in original container.
P260: Do not breathe.
P264: Wash hands thoroughly after handling.
P280::Wear protective gloves/eye protection/face protection.
P312: If you feel uncomfortable, call POISON CENTER or a doctor.
P301+P330+P331: If swallowed: rinse mouth. Do not cause vomiting.
P303+P361+P353: If in contact with skin (or hair). Take off/remove all contaminated clothing immediately. Rinse skin with water/shower.
P304+P340: If inhaled. Move victim to fresh air and keep at rest in a position comfortable for breathing.
P305+P351+P338: If in eyes: Carefully flush with water for several minutes. Remove contact lenses if available and easy to remove. Continue rinsing.
P363: Wash contaminated clothing before use.
P404: Store in a closed container.
P405: Store with a lock.
P390: Absorb spills to prevent material damage.
P501: Dispose of contents/containers through a waste management company authorized by the local government.

They were classified according to EU Directive 67/548/EEC or 1999/45/EC.
Hazard symbol.
nHazardous to the environment.
Risk Phrases.
R22-36-38:Harmful if swallowed. Irritating to eyes. Irritating to the skin.
R34 burns.
R41 = Risk of severe damage to eyes.
R51/53 is toxic to aquatic organisms and may cause long-term adverse effects on the marine environment.

Composition/composition information.
Composition:1-Hydroxyethylidene-1,1-diphosphonic acid or HEDP at 58-62%.
Chemical Abstract No.:2809-21-4.
European Inventory of Existing Chemical Substances No.:220-552-8.
First-aid measures.
Always seek medical attention after taking first aid measures.
Inhalation. Move to a new space of air. If not breathing, give artificial respiration. If breathing is difficult, give oxygen,Seek medical attention immediately.
Ingestion: Do not cause vomiting. Do not induce vomiting. Seek medical attention immediately. Do not give anything by mouth to an unconscious person.
Skin contact: Immediately wash skin with plenty of water for at least 15 minutes. Immediately rinse skin with plenty of water for at least 15 minutes. Remove contaminated clothing and shoes. I ask the doctor to treat and keep me healthy—Wash clothes before using again. Wash shoes thoroughly before using them. Wash shoes thoroughly before use and seek medical attention.

Eye contact. Immediately flush eyes with plenty of water for at least 15 minutes, occasionally elevating the upper and lower eyelids. Please do not allow the victim to rub his or her eyes. See a physician as soon as possible.
Fire Fighting Measures.

Fire:1-Hydroxyethylidene-1,1-phosphonic acid or HEDP phosphate is a slight fire hazard. The dust-air mixture may ignite or explode.

Extinguishing media. Use a method suitable for extinguishing surrounding fires in HEDP. Water spray may be used to keep containers exposed to fire cool. Dry chemicals, carbon dioxide, water, and foam are all acceptable.

Special Note: Appropriate methods can be used to extinguish fires over the HEDP. If a fire occurs over the HEDP, wear protective clothing and a NIOSH-approved self-contained breathing apparatus and operate under pressure-demand or another positive pressure mode.

Accidental release measures.
Personal precautions, protective equipment, environmental precautions, and emergency procedures. Avoid inhalation of dust/fume/gas/smoke/vapor/spray. Ventilate leaking or spill areas. Use personal protective equipment (waterproof boots, appropriate protective clothing, safety glasses, etc.).

Restrict unprotected personnel from entering the area. Prevent contact with hot surfaces. Do not approach wind. Do not come in contact with leaking materials. Keep away from drains, surface water, groundwater, and soil.

Methods of isolation and material cleanup procedures and storage. Seal spilled material. Clean up and containerize for recycling or disposal—recap with inert material.

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