Sodium phosphate

Sodium Phosphate

Sodium phosphate refers to the sodium salts of phosphoric acid, with several common forms differing in chemical composition and structure:

1. Common Types and Chemical Formulas

Sodium Dihydrogen Phosphate     Formula      NaH₂PO₄          Characteristics: Acidic salt, aqueous solution is weakly acidic   

Disodium Hydrogen Phosphate     Formula        Na₂HPO₄         Characteristics: Alkaline salt, aqueous solution is weakly alkaline   Trisodium Phosphate        Formula          Na₃PO₄           Characteristics: Strongly alkaline salt, aqueous solution is alkaline   Trisodium Phosphate Dodecahydrate    Formula    Na₃PO₄·12H₂O     Characteristics: Common crystalline form             

2. Physical Properties

- Appearance: White crystals or powder, highly soluble in water (solubility varies by type).

- Solubility:

  - Sodium Dihydrogen Phosphate: 59.8 g/100 mL (20°C)

  - Trisodium Phosphate: 12 g/100 mL (20°C)

- pH:

  - NaH₂PO₄ solution: ~4.5 (acidic)

  - Na₂HPO₄ solution: ~9 (alkaline)

  - Na₃PO₄ solution: ~12 (strongly alkaline)

3. Main Applications

- Food Industry:

  - Leavening agent (baked goods), emulsifier (cheese, meat products), pH regulator (beverages).

  - Commonly found in processed foods (e.g., ham, canned goods).

- Cleaning Agents:

  - Detergents, stain removers (softens water, removes calcium and magnesium ions).

- Pharmaceuticals:

  - Laxative (oral sodium phosphate solution for bowel cleansing).

  - Buffer agent (injections or eye drops, pH adjustment).

- Water Treatment:

  - Preservative, scale inhibitor (boiler water treatment).

- Laboratory:

  - Preparation of buffer solutions (e.g., PBS buffer).

  - Chemical analytical reagent.

4. Safety and Health

- Toxicity:

  - Excessive intake may lead to electrolyte imbalance (hyperphosphatemia).

  - Trisodium phosphate (Na₃PO₄) is strongly alkaline and may cause irritation upon contact with skin or eyes.

- Protection:

  - Wear gloves and goggles during handling, avoid inhaling dust.

- Environment:

  - Large-scale discharge may contribute to water eutrophication.

5. Precautions

- Storage: Keep sealed and moisture-proof, avoid contact with acids or strong oxidizers.

- Food-grade standards: Must comply with national food safety regulations (e.g., GB 25565-2010).