2-Phosphonobutane-1,2,4-tricarboxylic acid (PBTC) is a highly effective, low-phosphorus organic phosphonate used primarily as a scale and corrosion inhibitor in industrial water treatment.
Key Properties
Chemical Formula: C₇H₁₁O₉P
Molecular Weight: 270.13 g/mol
CAS Number: 37971-36-1
Appearance: Colorless to pale yellow transparent liquid (typically as a 50% aqueous solution)
Solubility: Completely miscible in water
pH (1% solution): 1.5 – 2.0
Density (20°C): ≥1.27 g/cm³ (for 50% solution)
Key Advantages & Performance
Superior Scale Inhibition: PBTC demonstrates excellent calcium carbonate and calcium sulfate scale inhibition. Its performance is significantly better than that of other common phosphonates like ATMP and HEDP, especially in high-temperature, high-hardness, and high-alkalinity water conditions.
Excellent Stability: It exhibits outstanding chemical stability against hydrolysis and h3 oxidizing agents (such as chlorine, bromine, and bleach), making it suitable for systems using aggressive biocides.
Enhances Zinc Solubility: PBTC can improve the solubility of zinc salts, which is beneficial in corrosion inhibition formulations, even at high pH levels (e.g., up to 9.5).
Low Environmental Impact: It contains very low phosphorus levels compared to other phosphonates, offering a favorable environmental profile. However, note that PBTC is not readily biodegradable, but it can undergo photodegradation in water.
Applications
PBTC is widely used in various industrial applications:
Cooling Water Systems: As a scale and corrosion inhibitor in industrial circulating and process cooling water.
Oilfield Water Injection: For scale inhibition in oilfield water injection systems.
Industrial Cleaning: As a chelating agent in detergents, cleaning agents, and descaling formulations.
Concrete: Used as a retarder to control the setting time of cement.
Metal Surface Treatment: As a corrosion inhibitor for steel.
Application Method
Dosage: When used alone, the typical dosage is 5-15 mg/L (ppm). For optimal performance, it is often used in combination with zinc salts, copolymers, and other water treatment chemicals. The specific dosage should be determined based on the system’s water quality through testing.
Safety & Handling
Hazards: PBTC is acidic and can cause irritation. Avoid contact with eyes, skin, and clothing.
First Aid: In case of splashing, immediately rinse with plenty of water.
Storage: Store in a cool, well-ventilated, indoor place. The typical shelf life is ten months.