1-Hydroxyethylidene-1,1-Diphosphonic Acid (HEDP)
CAS Number: 2809-21-4
HEDP is a cornerstone organophosphonate scale and corrosion inhibitor used across cooling water, boiler, and industrial water treatment programs. It demonstrates outstanding threshold inhibition of calcium carbonate scaling at very low concentrations and provides mild steel corrosion inhibition. Thermally stable up to 130°C and compatible with chlorine-based biocides.
Technical Specifications
| density | 1.40–1.45 g/cm³ |
| appearance | Colorless to light yellow liquid |
| HEDP content | 58–62% (60% grade) |
| chloride content | ≤0.05% |
| pH 1pct solution | 1.5–2.5 |
| phosphorus content as P | 18.5–19.5% |
Applications
- Cooling water carbonate scale inhibition at low doses
- Boiler water scale and corrosion prevention
- Domestic hot water circulation system protection
- Oilfield scale inhibitor in injection wells
- Metal surface cleaning and passivation pre-treatment
Key Features
- Threshold inhibition of CaCO3 scale at dosages as low as 1 mg/L
- Mild steel corrosion inhibition in alkaline cooling water
- Excellent chlorine tolerance — stable in oxidizing biocide programs
- Forms stable complexes with calcium, reducing scale nucleation sites
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