EDTMPS (Ethylene Diamine Tetra (Methylene Phosphonic Acid) Sodium Salt) is a nitrogen-containing organic polyphosphonate sodium salt, primarily used as a cathodic corrosion inhibitor and scale inhibitor in circulating cooling water and boiler water systems. Its corrosion inhibition efficiency is reported to be 3 to 5 times higher than that of inorganic polyphosphates.
Product Identity and Specifications
There is some ambiguity in the commercial naming, as different CAS numbers appear depending on the degree of sodium salt formation:
CAS 22036-77-7: Often associated with the octasodium salt formula
(molecular weight ~612).
CAS 1429-50-1: Also cited in some supplier listings for EDTMPS, though this is sometimes linked to the acid form (EDTMPA) or a different salt grade.
| Items | Index |
|---|---|
| Appearance | pale yellow transparent liquid |
| Active component (EDTMPS), % | 28.0min |
| Phosphorous acid (as PO33-), % | 5.0max |
| Phosphoric acid (asPO43- ), % | 1.0max |
| pH (1% water solution) | 9.5-10.5 |
| Density (20℃), g/cm3 | 1.25min |
| Chloride(Cl-), % | 3.0max |
Performance Characteristics
Scale Inhibition: Shows particularly good efficacy against calcium sulfate and barium sulfate scales. It remains effective at temperatures up to 200°C.
Chelation: In aqueous solution, it dissociates into multiple ions, allowing it to chelate with various metal ions and form stable complexes, which disrupts the normal crystallization of calcium scales.
Application and Dosage
Circulating Cooling Water: When used alone, the typical dosage is 2 – 10 mg/L.
Boiler Water Treatment: Often formulated with other agents. For example, a 1:3 ratio of EDTMPS to HPMA (hydrolyzed polymaleic anhydride) is used for low-pressure boilers. It can also be compounded with BTA, PAAS, or zinc salts.
Other Uses: Chelating agent in cyanide-free electroplating, water-softening agent in textile printing and dyeing, and peroxide bleaching stabilizer.
Storage and Safety
Storage: Keep in a shady, dry place. The typical storage period is ten months.
Safety: Generally described as low-toxicity and non-polluting, but standard industrial handling precautions (avoiding direct skin/eye contact) apply.
Note: The specific CAS number and exact active content can vary by supplier. Always confirm the technical data sheet (TDS) and safety data sheet (MSDS) of the specific product batch you receive.
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