Sodium Tripolyphosphate (STPP)
is an inorganic compound with the chemical formula Na₅P₃O₁₀. It belongs to the family of polyphosphate salts and appears as a white crystalline powder. It is highly soluble in water, and its aqueous solution is weakly alkaline (with a pH of approximately 9-10). STPP is widely used in industrial and food applications, primarily as an emulsifier, chelating agent, water softener, and preservative.
Physical and Chemical Properties
| Appearance and properties: | White powder |
| Density: | >1.5 g/cm³ (20°C) |
| Melting point: | 622 °C |
| Water solubility: | 20 g/100 mL (20 °C) |
| Stability: | Stable. Incompatible with strong oxidizing agents, strong acids. Hygroscopic. |
| Storage conditions: | Store in a tightly closed container. Store in a cool, dry, well-ventilated area away from incompatible substances. Store protected from moisture. |
| RTECS Number: | YK4570000 |
| Safety instructions: | S26-S36-S24/25 |
| WGK Germany: | 1 |
| Danger Class code: | R36/37/38 |
| Customs Code: | 2835319000 |
| Dangerous goods mark: | Xi |
Specifications
| Appearance | White to light yellow crystalline powder |
| Loss on drying | ≤1.0% |
| pH value | 3.0-4.5 |
| Water solubility (100g/L) | Colorless to pale yellow transparent liquid |
| Melting point | 111.0-116.0℃ |
| Content | ≥99.0% |
| Suggested dosage | 0.5-3.0% |
| Usage suggestions | The whitening and spot removing effect is most significant under pH 3.0-6.0 conditions; Easy to dissolve in water, easy to dissolve in ethanol, slightly soluble in oil and fat |
| Package | 1.0kg/bag |
| Storage condition | Sealed storage at room temperature |
| Quality guarantee period | 2 years |
Physical and Chemical Properties
- Appearance: White crystalline powder or granules.
- Density: 2.52 g/cm³ (at 20°C).
- Melting Point: 622°C (decomposition).
- Solubility: Highly soluble in water, with a solubility of 20 g/100 mL at 20°C.
- pH Value: Weakly alkaline (9.0-10.0) in aqueous solution.
- Hygroscopicity: Hygroscopic, readily absorbs moisture from the air.
Production Method
STPP is typically produced through the reaction of phosphoric acid (H₃PO₄) with sodium hydroxide (NaOH) or sodium carbonate (Na₂CO₃). The process includes neutralization, polymerization, and cooling steps, ultimately yielding crystalline STPP. The production process is as follows:
- Neutralization Reaction: Phosphoric acid reacts with a sodium source to form monosodium phosphate and disodium phosphate.
- Polymerization Reaction: The phosphate units are polymerized by controlled heating (350-450°C) to form STPP.
- Cooling and Formation: After cooling, the product is ground and sieved to obtain the desired powder or granular form.
Applications
STPP is widely used across multiple industries due to its multifunctional properties:
Detergent Industry
- Water Softening: Acts as a builder to soften water by preventing calcium and magnesium ions from binding with detergent, thereby enhancing cleaning efficiency.
- Anti-redeposition: Prevents stains from re-depositing on fabrics, improving overall washing performance.
Food Industry
- Emulsifier and Preservative: Used in meats, seafood, and processed foods to retain moisture and improve texture.
- Canned Foods: Prevents spoilage and extends shelf life in canned products.
Water Treatment Industry
- Scale Inhibitor: Removes calcium and magnesium ions from water to prevent scaling in pipes and equipment.
Ceramics and Building Materials Industry
- Dispersant: Improves the dispersion and flowability of ceramic raw materials, reducing production defects.
Leather Industry
- Tanning and Softening: Used in the tanning and softening processes to remove fats and improve leather quality.
Other Applications
- Petroleum, Metallurgy, and Paper Industries: Used as a dispersant and water softener.
STPP Sodium Tripolyphosphate
STPP Sodium Tripolyphosphate
STPP Sodium Tripolyphosphate
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