HEDP 60% Liquid Hydroxyethylidene diphosphonic acid HEDP
HEDP is an organophosphonic acid scale and corrosion inhibitor that can form stable complexes with various metal ions such as iron, copper, and zinc, and can dissolve oxides on metal surfaces.When used in combination with other water treatment agents, it demonstrates an ideal synergistic effect.
1-Hydroxy Ethylidene-1,1-Diphosphonic Acid (HEDP)
CAS No. 2809-21-4
Synonyms: Hydroxyethylidene diphosphonic acid, HEDPA, (1-hydroxyethylidene) diphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid
Molecular Formula: C2H8O7P2
Relative Molecular Weight: 206.02
I. Properties and Uses
HEDP is an organophosphonic acid scale and corrosion inhibitor that can form stable complexes with various metal ions such as iron, copper, and zinc, and can dissolve oxides on metal surfaces. It maintains good scale and corrosion inhibition at 250℃, remains stable at high pH, is not easily hydrolyzed, and is generally not easily decomposed under light and heat conditions. Its acid and alkali resistance and chlorine oxidation resistance are better than other organophosphonic acids (salts). HEDP can form hexacyclic chelates with metal ions in water, especially calcium ions, thus exhibiting good scale inhibition and a significant 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 cold winter regions; it is particularly suitable as a cleaning agent in the electronics industry and as an additive in daily chemical products.
HEDP is widely used in circulating cooling water systems in power, chemical, metallurgical, and fertilizer industries, as well as in medium and low-pressure boilers, oilfield water injection, and oil pipelines for scale inhibition and corrosion inhibition. In the light textile industry, it can be used as a cleaning agent for metals and non-metals, a peroxide stabilizer and fixing agent in the dyeing industry, a complexing agent in the cyanide-free electroplating industry, and a carrier for radioactive elements in the pharmaceutical industry.
II. Technical Specifications
| Item | Standard | ||
| 50% Liquid | 60% Liquid | solid | |
| Appearance | colorless to pale yellow aqueous solution | colorless to pale yellow aqueous solution | White crystal powder |
| Active content(HEDP), % | ≥50.0 | ≥60.0 | — |
| Phosphorous acid (as PO3 3-), % | ≤2.0 | ≤1.5 | ≤0.8 |
| Phosphoric acid (as PO4 3-), % | ≤0.8 | ≤0.4 | ≤0.5 |
| Chloride (as Cl–), ppm | ≤0.02 | ≤0.02 | ≤0.01 |
| pH (1% water solution) | 1.5-2.0 | 1.5-2.0 | 1.5-2.0 |
| Density (20℃) g/cm3 | ≥1.36 | ≥1.44 | — |
| Calcium chelation value(mg/g) | ≥450 | ≥500 | — |
| Iron (as Fe²⁺) content(mg/L) | ≤20.0 | ≤20.0 | ≤10 |
| Active content (HEDP·H2O), % | — | — | ≥98.0 |
III. Usage Methods
When used as a scale inhibitor, the general concentration of HEDP is 1–10 mg/L; when used as a corrosion inhibitor, the general concentration is 10–50 mg/L; when used as a cleaning agent, the general concentration is 1000–2000 mg/L; it is usually used in combination with polycarboxylate-based scale and dispersants. When used in other industries, the dosage should be determined based on testing.
IV. Packaging and Storage
HEDP liquid is packaged in plastic drums, 30kg or 250kg per drum; HEDP solid is packaged in plastic woven bags lined with polyethylene bags, 25kg net weight per bag, or as required by the user. Store in a cool, ventilated place indoors, protected from moisture. Shelf life is twelve months.
V. Safety Precautions
HEDP is acidic. Take precautions during handling to avoid contact with skin and eyes. If contact occurs, immediately rinse with plenty of water.