What is the application principle of DTPMP•Na2

DTPMP·Na₂ is a highly effective phosphonic acid-based scale and corrosion inhibitor, widely used in water treatment, oilfield operations, and industrial processes. Its functionality stems from its multiple phosphonate groups (–PO₃H₂) and amine nitrogen atoms, enabling h3 chelation, dispersion, and threshold inhibition.

1. Core Functional Mechanisms

(1) Scale Inhibition (Antiscaling)

Chelation of Metal Ions:

Strongly binds Ca²⁺, Mg²⁺, Ba²⁺, Sr²⁺, Fe²⁺/Fe³⁺, preventing the formation of insoluble salts (e.g., CaCO₃, CaSO₄, BaSO₄).

Stability constants (log K):

Ca²⁺ ~ 8.5, Fe³⁺ > 20 (extremely high affinity for iron).

Threshold Effect:

Works at sub-stoichiometric dosages (1–10 ppm) by distorting crystal growth, making scales soft and non-adherent.

(2) Corrosion Inhibition

Anodic Passivation:

Forms a protective film on metal surfaces (carbon steel, copper), reducing oxidation.

Synergistic Effects:

Enhances performance when combined with zinc salts (Zn²⁺) or molybdate (MoO₄²⁻) for cathodic protection.

(3) Dispersion of Suspended Particles

Electrostatic Repulsion:

The negatively charged phosphonate groups prevent particle agglomeration (e.g., Fe₂O₃, clay, silica).

Iron Stabilization:

Keeps soluble iron (Fe²⁺) in solution, preventing Fe(OH)₃ precipitation.

2. Key Applications

Industry Function Typical Dosage

Cooling Water Prevents CaCO₃, Ca₃(PO₄)₂ scaling; protects heat exchangers. 5–20 mg/L

Oilfield (Injection Water) Inhibits BaSO₄/SrSO₄ scaling in high-salinity brines. 10–50 mg/L

RO/Desalination Controls CaSO₄ and silicate scaling in membranes. 2–10 mg/L

Textile Dyeing Sequesters Fe³⁺/Ca²⁺ to prevent dye precipitation. 0.1–0.5% solution

Pulp & Paper Reduces calcium oxalate deposits in paper machines. 1–5 kg/ton pulp

3. Advantages Over Other Phosphonates

✔ Higher chelation capacity (5 phosphonate groups vs. HEDP’s 2).

✔ Better Fe³⁺ stabilization (critical in systems with iron corrosion).

✔ Stable at high temperatures (up to 200°C in acid, 120°C in alkaline conditions).

✔ Resistant to chlorine/oxidizers (unlike ATMP, which degrades faster).

4. Technical Specifications (Example)

Parameter Typical Value

Appearance Amber to colorless liquid

Active Content 50–60%

pH (1% solution) 2.0–4.0

Density (20°C) 1.30–1.40 g/cm³

Phosphorus (as P) ~15%

5. Recommended Usage & Compatibility

Optimal pH Range: 2–12 (works in both acidic and alkaline systems).

Synergistic Blends:

With polyacrylates (PAA) for enhanced dispersion.

With Zn²⁺ for improved corrosion inhibition.

Avoid: High doses of Al³⁺/Fe³⁺ (may form insoluble complexes).

6. Environmental & Safety Notes

Biodegradability: Low (persistent in water; requires controlled discharge).

Toxicity: Moderate (LD50 ~ 2,000–5,000 mg/kg; handle with PPE).

Regulatory Compliance: Meets EPA and REACH standards (but restricted in some regions due to phosphorus content).

Conclusion

DTPMP·Na₂ is a versatile, high-performance scale/corrosion inhibitor, especially effective in high-iron, high-hardness, and high-temperature systems. Its multiple phosphonate groups provide superior chelation and stabilization compared to HEDP or ATMP, making it ideal for oilfield, cooling water, and RO applications. For best results, conduct water chemistry analysis to optimize dosage and formulation.