Overview
Diphosphoric acid (CAS 2466-09-3 ), also known as pyrophosphoric acid, is an inorganic condensed phosphoric acid used across food processing, pharmaceutical manufacturing, and water treatment.
It functions as a pH buffer, chelating agent, and stabilizer, controlling mineral interactions and acid balance in complex formulations. In food processing, it regulates acidity and sequesters metal ions.
These ions would otherwise accelerate oxidative spoilage in packaged and processed products. Pharmaceutical manufacturers use it as a buffering agent in liquid formulations where precise pH control is critical.
This stability is essential for active ingredients. In water treatment, it chelates calcium and magnesium ions to prevent scale formation in industrial cooling and distribution systems.
It also acts as a sequestrant in emulsified and dairy-based products, preventing discoloration and texture degradation caused by trace metal contamination during the manufacturing process.
Diphosphoric acid is supplied as a liquid solution, with concentration and purity varying by application. Food-grade and technical-grade specifications are the most commonly available formats.
Pharmaceutical-grade material is supplied to USP or Ph. Eur. standards where required. Buyers should confirm grade, concentration, and packaging format with their chemical suppliers.
Specifications can differ significantly between industrial and regulated end-use markets. Proper documentation ensures compliance with safety and quality requirements for specific industrial applications.
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Physical Properties
| Melting Point | 61 °C |
| Density | approximate 1.9g/ml (25℃) |
| Appearance | White to very pale yellow glassy solid |
| Color | white crystals, crystalline |
| Form | white crystals |
| Water Solubility | 709g/100mL H2O (23°C); soluble alcohol, ether [MER06] |
| pH | pKa1= 0.86, pKa2 = 1.76, pKa3 = 5.88, pKa4 = 8.14(25℃) |
Safety & Handling
Danger GHS05 GHS07 Hazard Statements H302 Harmful if swallowed H314 Causes severe skin burns and eye damage H318 Causes serious eye damage H332 Harmful if inhaled Precautionary Statements P260 Do not breathe dust/fume/gas/mist/vapours/spray. P261 Avoid breathing dust/fume/gas/mist/vapours/spray. P264 Wash … thoroughly after handling. P270 Do not eat, drink or smoke when using this product. P271 Use only outdoors or in a well-ventilated area. P280 Wear protective gloves/protective clothing/eye protection/face protection. P316 Get emergency medical help immediately. P317 Get emergency medical help. P321 Specific treatment (see … on this label). P330 Rinse mouth. P363 Wash contaminated clothing before reuse. P405 Store locked up. P501 Dispose of contents/container in accordance with local regulations. P264+P265 Wash … thoroughly after handling. P301+P317 Get emergency medical help. P304+P340 IF INHALED: Remove person to fresh air and keep comfortable for breathing. P301+P330+P331 Rinse mouth. Do NOT induce vomiting. P302+P361+P354 IF ON SKIN: Take off immediately all contaminated clothing. Rinse skin with water/shower. P305+P354+P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
Trade & Regulatory
| HS Code | 28092000 |
| UN Number | 3260 |
| ADR Class | 8 |
| Packing Group | II |
| WGK (Germany) | 3 |
Other Names
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Chemical Properties
- CAS Number
- 2466-09-3
- EC Number
- 219-574-0
- Mol. Weight
- 177.98
- HS Code
- 28092000
- Category
- Chelating Agents