Preparation of calcium citrate and sodium citrate from limes (Citrus aurantifolia).

Calcium citrate was precipitated from lime juice after distillation of oil, using calcium carbonate. Addition of calcium carbonate to cold juice and heating gave a superior calcium citrate compared to that prepared by addition of calcium carbonate to hot juice. Sodium citrate was prepared by reacting calcium citrate with sodium carbonate. Mixing the 2 reactants either at room temp. or 90 degree C and immediate analysis thereafter indicated that 35-36% of the sodium carbonate added remained unreacted; this was reduced to 14-15% after 30 min. Heat did not appear to enhance the speed of reaction, nevertheless it was found necessary to prevent the Ca salts from interfering at the time of concn. On crystallization, 88-94% of sodium citrate present in the filtrate was collected in 3 crops of greater than 09% purity. Studies on solubility of sodium citrate showed that the pentahydrate crystallized below 40 degree C and the dihydrate crystallized at approximate equal to50 degree C.