Electrochemical methods for recovery of ascorbic acid

A method for the production of ascorbic acid and a co-product base comprising the following steps:

• a) providing an electrochemical cell comprising an anode, the anode rinsed with an anolyte stream, a cathode, the cathode rinsed with a catholyte stream, and an electrodialysis cell stack disposed between the anode and the cathode, the electrodialysis cell stack comprises at least one feed compartment, at least one base compartment and alternating bipolar and cation exchange membranes disposed between the feed and base compartments;
• b) introducing into the feed compartment a feed electrolyte solution comprising an ascorbate salt and an inorganic salt;
• c) introducing into the base compartment a base electrolyte comprising a base;
• and
• d) applying a sufficient voltage across the anode and cathode to convert the ascorbate salt into an ascorbate ion and salt cation, and to form protons and hydroxyl ions at the bipolar membrane, wherein the protons migrate to the feed compartment and combine with the ascorbate ion to form ascorbic acid, the salt cation migrates through the cation exchange membrane into the base compartment to combine with the hydroxyl ions in the base compartment thereby forming the co-product base.

A method for the production of ascorbic acid and co-product methoxide salt comprising the following steps:

• a) providing an electrochemical cell comprising an anode, the anode rinsed with an anolyte stream, a cathode, the cathode rinsed with a catholyte stream, and an electrodialysis cell stack disposed between the anode and the cathode, the electrodialysis cell stack comprises at least one feed compartment, at least one base compartment and alternating bipolar and cation exchange membranes disposed between the feed and base compartments;
• b) introducing into the feed compartment a feed solution comprising an ascorbate salt and an inorganic salt, substantially dissolved in methanol;
• c) introducing into the base compartment a base electrolyte comprising a base;
• and
• d) applying a sufficient voltage across the anode and cathode to convert the ascorbate salt into an ascorbate ion and salt cation, and to form protons and methoxyl ions at the bipolar membrane, wherein the protons migrate to the feed compartment and combine with the ascorbate ion to form ascorbic acid, the salt cation migrates through the cation exchange membrane into the base compartment to combine with the methoxyl ions in the base compartment thereby forming the co-product methoxide salt.

A method to produce ascorbic acid and a co-product base in a two compartment electrochemical cell with a gas diffusion anode comprising the following steps:

• a) providing an electrochemical cell comprising a gas diffusion anode in an anolyte compartment, a cathode in a catholyte compartment, and a cation exchange membrane disposed between the anolyte and catholyte compartments;
• b) introducing into the anolyte compartment an anolyte comprising an ascorbate salt and an inorganic salt;
• c) introducing into the catholyte compartment a catholyte;
• d) introducing into the gas diffusion anode a source of hydrogen gas;
• and
• e) applying a sufficient voltage across the anode and cathode to convert the ascorbate salt into an ascorbate ion and salt cation, and to form protons at the anode and hydroxyl ions at the cathode wherein the protons, in the anolyte compartment, combine with the ascorbate ion, to form ascorbic acid and the salt cation migrates through the cation exchange membrane into the catholyte compartment to combine with hydroxyl ions thereby forming the co-product base.