Calcium citrate
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Chemical formula | Ca3(C6H5O7)2 |
---|---|
OTP appearance | white solid |
Molar Mass(g/mol) | 498 |
Density(g/cc) | 1.6 |
Melting Point(°C) | 120 |
Boiling Point(°C) | decomposes |
Solubility in water(g/L) | 0.8 |
Solubility in ethanol(g/L) | non |
NFPA 704 |
Calcium citrate is an important salt of calcium for nutritional supplementation, and a stable compound for storage of citrate.
Uses
Primary
- Feedstock for oral rehydration salts
- Storage of citrate for other uses
- Intermediate in purification of citric acid from citrus juice
Natural Occurrence
- Does not occur naturally
Hazards
- GRAS, food supplement
Production
Extraction
citrus fruits contain two main acids: citric acid and ascorbic acid. Extraction and isolation of calcium citrate occurs as follows:
- Filter juice of citrus fruit
- Discard residue
- Acidify to pH ~2 with hydrochloric acid
- Filter
- Discard residue
- Basify to pH 8-9 via sodium hydroxide
- Filter
- Discard residue
- Add calcium chloride in proportion to the sodium hydroxide used (1:2 molar) while warming, precipitating calcium citrate
- 2 Na3C6H5O7(aq) + 3 CaCl2(aq){3 Ca2C6H5O7(s) + 6 NaCl(aq)Δ}→
- 2 Na3C6H5O7(aq) + 3 CaCl2(aq)
- Filter
- Discard filtrate