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Hydroxyethylidene Diphosphonic Acid HEDP

Hydroxyethylidene Diphosphonic Acid HEDP

Alternative names: hydroxyethylidene diphosphonic acid, HEDPA, (1-hydroxyethylidene) diphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid

Category:

Organophosphorus scale and corrosion inhibitor chelating agent

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Keywords:

Organophosphorus scale and corrosion inhibitor chelating agent

Detailed introduction

Also known as: Hydroxyethylidene diphosphonic acid, HEDPA, (1-hydroxyethylidene) diphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid

CAS No.2809-21-4

Molecular formula: C₂H₈O₇P₂

Relative molecular mass: 206.03

Structural formula:

Performance and Applications:

HEDP is an organic phosphonic acid‑based scale inhibitor and corrosion retardant that forms stable complexes with various metal ions, including iron, copper, and zinc, and can dissolve oxide layers on metal surfaces. It maintains excellent corrosion inhibition and scale‑prevention performance even at 250°C, remains highly stable under high pH conditions, is resistant to hydrolysis, and is generally resistant to decomposition under normal light and thermal exposure. Its resistance to acids and alkalis, as well as its stability against chlorine oxidation, surpasses that of other organic phosphonates (salts). HEDP can form six‑membered chelate rings with metal ions in water, particularly calcium ions, thereby delivering superior scale‑inhibition and exhibiting a pronounced solubility‑limit effect. When used in combination with other water‑treatment agents, it demonstrates an ideal synergistic effect.

HEDP solid is a high-purity product, suitable for regions with severe winter cold; it is particularly well-suited as a cleaning agent in the electronics industry and as an additive in daily-use chemical products.

HEDP is widely used in industrial circulating cooling water systems across sectors such as power generation, chemical processing, metallurgy, and fertilizer production, as well as in medium- and low-pressure boilers, oilfield water injection, and oil pipelines, where it serves to inhibit scale formation and mitigate corrosion. In the light‑textile industry, it functions as a cleaning agent for both metallic and nonmetallic surfaces; in the dyeing and bleaching industries, it acts as a peroxide stabilizer and color fixative; in cyanide‑free electroplating, it serves as a complexing agent; and in the pharmaceutical sector, it is employed as a carrier for radioactive isotopes.

Technical Indicators:

Project	Indicator
Project	Complies with GB/T 26324-2010	——	Complies with HG/T 3537-2010
Appearance	Colorless or pale yellow transparent liquid		White crystals
Active ingredient (expressed as HEDP) %	≥50.0	≥60.0	≥90.0
Active ingredient (expressed as HEDP·H) ₂ O count)%	——	——	≥97.0
Phosphorous acid (as PO ₃^3- Accounting)%	≤2.0	≤2.0	≤0.8
Phosphoric acid (as PO ₄^3- Accounting)%	≤0.8	≤0.8	≤0.5
Chloride (as Cl) ^- Calculation)ug/g	≤200	≤100	≤100
Iron (as Fe²⁺) ⁺ Content (mg/L)	≤20.0	≤10.0	≤10.0
Density (20°C) g/cm³	≥1.36	≥1.40	——
Calcium chelation value mg/g	≥450	≥500	——
pH (1% aqueous solution)	1.5-2.0	1.5-2.0	1.5-2.0

Instructions for use:

HEDP is typically used at concentrations of 1–10 mg/L as a scale inhibitor, 10–50 mg/L as a corrosion inhibitor, and 1,000–2,000 mg/L as a cleaning agent; it is usually employed in combination with polycarboxylate‑based scale inhibitors and dispersants. When used in other industries, the appropriate dosage should be determined through testing.

Packaging and Storage:

HEDP liquid is packaged in plastic drums, with each drum containing 25 kg or 250 kg, or as specified by the customer. The solid form is packed in polyethylene-lined plastic woven bags, with a net weight of 25 kg per bag, or as requested by the customer. Store in a cool, well-ventilated indoor location, protected from moisture; shelf life is twelve months.

Security Protection:

HEDP is an acid; take appropriate personal protective measures during handling, and avoid contact with skin, eyes, etc. If contact occurs, rinse immediately with plenty of water.

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Hydroxyethylidene Diphosphonic Acid GBT26324-2010

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