| 摘要 |
<p>PURPOSE:To separate and purity citric acid from a fermented solution or crude crystal of citric acid by making use of difference in solubility of sodium citrate and sodium isocitrate in an aqueous solution of carbon dioxide gas under a supercritical condition. CONSTITUTION:A mixture excellent citric acid and isocitric acid is sealed in a pressure container, maintained at 30-60 deg.C, pressurized with a carbon dioxide gas under 73-400kg/cm<2> and a water-containing carbon dioxide gas (preferably carbon dioxide gas containing at least one of water, alcohol, ether and hydrocarbon) is circulated through the mixture. The interior of the pressure container is made into a gas-solid coexisting state, the fluid is discharged from the coexisting system while maintaining the pressure and the residual solid and gas are collected, respectively to separate and purify citric acid and isocitric acid. Crystal having 80-95wt.% removal ratio of isocitric acid and >=95wt.% purity of citric acid is obtained from the mixture of citric acid and isocitric acid.</p> |
