Product information
Product name: 1-Hydroxyethylidene-1,1-Diphosphonic Acid (HEDP)CAS No.: 2809-21-4
EINECS No.: 220-552-8
Synonyms: Etidronic Acid, Dequest 2010
Molecular Formula: C2H8O7P2
Molecular Weight: 206.031.
Typical Physical & Chemical Properties
| Melting Point | 198 ~ 199 ℃ (decomposition) |
| Boiling Point | ~579 ℃ (predicted) |
| Flash Point | 303.8 ℃ |
| Solubility | Freely soluble in water; slightly soluble in methanol & ethanol |
| pKa (25℃) | 1.35, 2.87, 7.03, 11.3 |
| Vapor Pressure | Extremely low at ambient temperature |
| Stability | Stable under wide pH range, resistant to hydrolysis; decomposes above 250℃ |
Quality Specifications
| Item | 60% Aqueous Solution | 98% Solid Crystal | Test Method |
|---|---|---|---|
| Appearance | Clear colorless to pale yellow liquid | White crystalline powder | Visual Inspection |
| Active Content (as HEDP) | ≥60.0 % | ≥98.0 % | Potentiometric Titration |
| Phosphorous Acid (as PO33−) | ≤2.0 % | ≤0.8 % | Iodometric Titration |
| Phosphoric Acid (as PO43−) | ≤0.8 % | ≤0.5 % | Spectrophotometry |
| Chloride (as Cl−) | ≤0.02 % | ≤0.01 % | Turbidimetry |
| Iron (Fe) | ≤35 ppm | ≤5 ppm | AAS |
| pH (1% aqueous solution, 25℃) | 1.3 ~ 2.0 | — | pH Meter |
| Density (20℃) | ≥1.40 g/cm³ | — | Hydrometer |
| Calcium Sequestration Value | ≥500 mg CaCO₃/g | — | Standard Sequestration Test |
| Color (Pt-Co) | ≤80 Hazen | — | Platinum-Cobalt Method |
Product Characteristics
Excellent chelating capacity with metal ions: Ca²⁺, Mg²⁺, Fe³⁺, Cu²⁺, Zn²⁺.
Powerful scale inhibition and corrosion inhibition performance.Good thermal stability, effective at working temperature up to 200 ℃.
Low toxicity, good compatibility with other water treatment chemicals.
No phosphorus precipitation under common operating conditions.
Applications
Circulating cooling water, boiler water, oilfield water treatment: scale & corrosion inhibitor.
Industrial cleaning agent, metal surface rust remover.Non-cyanide electroplating complexing agent.
Cosmetics & personal care: stabilizer, metal ion sequestrant.
Detergent, textile printing & auxiliaries.
Handling & Storage
Store in tightly sealed plastic-lined containers, cool, ventilated warehouse.
Avoid contact with strong oxidants, strong alkalis.Prevent skin and eye contact; wear chemical resistant gloves & goggles.
Do not mix with hypochlorite bleaching agent directly.
Packaging
60% liquid: 250 kg plastic drum / IBC tank
98% solid: 25 kg plastic woven bag with inner PE liner
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