Technical Specifications of Ethylenediamine Tetra(Methylene Phosphonic Acid) Sodium Salt (EDTMPS)

Ethylenediamine Tetra(Methylene Phosphonic Acid) Sodium Salt (EDTMPS) is a nitrogen-containing organic polyphosphonic acid salt. It stands out in industrial water treatment because of its high chemical stability, excellent threshold scale inhibition, and superior metal-chelating capacity (especially for calcium and iron) compared to typical non-nitrogen phosphonates.

Below are the standard industrial technical specifications for both the liquid concentrate and solid powder forms of EDTMPS.

1. General Chemical Profiles

Chemical Name: Ethylenediamine Tetra(Methylene Phosphonic Acid) Sodium Salt

Synonyms: EDTMPS; EDTMP Na; Sodium EDTMP

CAS Number: 1429-50-1 (for the base acid/salt variants) or 22042-96-2

Molecular Formula: C₆H₁₂O₁₂N₂P₄Na₈   

2. Technical Specification Sheet

Industrial production generally offers EDTMPS in two standard grades. The table below represents the benchmark parameters compliant with international water treatment chemical standards:

Items Index

Appearance pale yellow transparent liquid

Active component (EDTMPS), % 28.0min

Phosphorous acid (as PO₃^3-), % 5.0max

Phosphoric acid (asPO₄^3- ), % 1.0max

pH (1% water solution) 9.5-10.5

Density (20℃), g/cm³ 1.25min

Chloride(Cl-), % 3.0max

3. Key Performance Properties

High Calcium Tolerance

Unlike standard phosphonates (like HEDP or ATMP) which can precipitate out of solution if calcium hardness levels are extremely high, EDTMPS forms highly stable water-soluble chelates. It rarely forms insoluble calcium phosphonate precipitates even in high-alkalinity, high-hardness water.

Exceptional Threshold Inhibition

It blocks crystal nucleating points effectively at sub-stoichiometric dosages. A concentration of just 3–10 mg/L is typically sufficient to inhibit barium sulfate (BaSO₄) and strontium sulfate (SrSO₄) scaling, which are notoriously difficult to dissolve once formed.

Corrosion Inhibition Synergy

When combined with inorganic phosphates, zinc salts, or molybdate formulations, EDTMPS functions as a powerful cathodic corrosion inhibitor by helping form a protective, micro-thin molecular film on carbon steel surfaces.

Storage and Safety Note: Liquid EDTMPS is alkaline to slightly neutral but should still be handled with standard chemical personal protective equipment (PPE). Store in high-density polyethylene (HDPE) or coated steel drums. Avoid direct exposure to h3 oxidizing agents over prolonged periods, which can slowly cleave the nitrogen-carbon bonds.