Abstract: A continuous electrodeionization apparatus and method. The continuous electrodeionization apparatus and method provide improved removal of weakly ionized ions, particularly silica. The apparatus and method involves using macroporous ion exchange resins that are both highly crosslinked and have a high water content. In preferred embodiments, the ion exchange resin beads also have a substantially uniform diameter.

Abstract: An improved electrodeionization apparatus and method are provided. The electrodeionization apparatus includes electrolyte compartments, ion-concentrating, and ion-depleting compartments, having electroactive media therein. The electroactive media can be induced to have a reversible change in its chemical or electrical properties upon imposition of an external electrical field or the presence of an electrically charged substance. The change in chemical or electrical properties of the media results in a desired change in the transport or chemical properties of the media. The incorporation of the improved electroactive media also provides for an improved, and more reliable electrodeionization process in applications requiring chemical and temperature resistance media, where localized pH shifts would be harmful to the product being deionized, under temperature and chemical conditions of the liquid to be processed, or under circumstances where traditional media would tend to foul.

Abstract: An electrodeionization apparatus is provided for removing ions from liquids. The apparatus is particularly well-adapted for the removal of large, heavily hydrated, highly charged or weakly ionized molecules or complexes from feed water. Such removal is achieved by substituting, in at least one section of the apparatus, ion exchange membranes and/or resins having lower crosslinking and/or lower selectivity, for the ion exchange membranes commonly used in electrodeionization systems. Methods for reducing the electrical resistance across the membrane also are provided.

Abstract: An electrodeionization apparatus is provided for removing ions from liquids. The apparatus is particularly well adapted for the removal of large, heavily hydrated, highly charged or weakly ionized molecules or complexes from feed water. Such removal is achieved by substituting, in at least one section of the apparatus, ion exchange membranes and/or resins having lower crosslinking and/or lower selectivity, for the ion exchange membranes commonly used in electrodeionization systems. Methods for reducing the electrical resistance across the membrane also are provided.

Abstract: Purified ion exchange resin particles are provided in a bifunctional electrodeionization step having anion depletion compartments containing anion exchange resin particles which are purified and cation depletion compartments containing cation exchange resin particle which are purified as well as ion concentration compartments. The bifunctional electrodeionization step for purifying resin particles is conducted under conditions to disassociate water into hydrogen ions and hydroxyl ions. Purified water having a purity of at least 1 megohm-cm is introduced into the anion depletion compartment and cation depletion compartments and water for accepting ionic impurities is introduced into the ion concentration compartments. The purified water is produced in an initial purification step which also can be an electrodeionization step.

Abstract: An electrodeionization apparatus and process are provided for removing ions from liquids. Liquid to be purified is passed through depleting compartments containing mixed anion and cation exchange resin beads while a second liquid is passed through concentrating compartments also containing ion exchange resin beads. Ions, under influence of a D.C. potential, pass from the depleting compartments into the concentrating compartments through ion permeable membranes. The beads in the depleting compartments are housed within subcompartments of controlled width and thickness and are retained therein by the ion permeable membranes which are secured to the walls of the subcompartments. Means are provided for reversing the polarity of the D.C. potential to convert the depleting compartments to concentrating compartments and the concentrating compartments to depleting compartments. Means are provided for continuously recovering purified water from the apparatus regardless of the polarity of the D.C.

Abstract: An electrodeionization apparatus is provided for removing ions from liquids. Liquid to be purified is passed through at least two ion depletion compartments containing mixed anion and cation exchange resin beads in a given separation stage. A second liquid is passed through concentration compartments free of ion exchange resin beads. Ions under the influence of D.C. potential pass from the depletion compartments into the concentration compartments through ion permeable membranes. The beads in the depletion compartments are housed within subcompartments of controlled width and thickness and are retained therein by the ion permeable membranes which are secured to the walls of the subcompartments.

Abstract: An electrodeionization apparatus and process are provided for removing ions from liquids. Liquid to be purified is passed through depleting compartments containing mixed anion and cation exchange resin beads while a second liquid is passed through concentrating compartments free of ion exchange resin beads. Ions, under influence of a D.C. potential, pass from the depleting compartments into the concentrating compartments through ion permeable membranes. The beads in the depleting compartments are housed within subcompartments of controlled width and thickness and are retained therein by the ion permeable membranes which are secured to the wall of the subcompartments.

Abstract: A pretreatment step for the defouling of the compartments used in electrodeionization apparatus in which a solution of sodium percarbonate is contacted with the compartments to break up agglomerations of organic contaminants and colloidal films as well as to kill bacteria resident within the system. After this pretreatment step any conventional cleaning may be performed to complete the cleaning cycle.

Abstract: An electrodeionization apparatus and process are provided for removing ions from liquids. Liquid to be purified is passed through depleting compartments containing mixed anion and cation exchange resin beads while a second liquid is passed through concentrating compartments free of ion exchange resin beads. Ions, under influence of a D.C. potential, pass from the depleting compartments into the concentrating compartments through ion permeable membranes. The beads in the depleting compartments are housed within subcompartments of controlled width and thickness and are retained therein by the ion permeable membranes which are secured to the walls of the subcompartments.

Abstract: This invention describes the process of separating dextrose preferentially from a mixture of dextrose and oligosaccharides by using ion exchange membranes. More particularly it relates to the process comprising the steps of (1) passing a liquid mixture of dextrose and oligosaccharides through a first feed chamber of an electro-osmosis cell comprising at least two chambers defined between ion exchange membranes having alternating high and low permeability coefficients with respect to each other, (2) passing a direct electric current transversely through said membranes and chambers in a direction to cause the dextrose to pass from said feed chamber through said high permeability coefficient membrane into a second chamber with said dextrose being substantially retained in the second chamber, and (3) recovering an oligosaccharide enriched and a dextrose enriched effluent from the separate chambers.

Abstract: This invention describes the process of separating fructose preferentially from a mixture of glucose and fructose by using ion exchange membranes. More particularly it relates to the process comprising the steps of (1) passing a liquid mixture of fructose and glucose through a first feed chamber of an electro-osmosis cell comprising at least two chambers defined between ion exchange membranes having alternating high and low permeability coefficients with respect to each other, (2) passing a direct electric current transversely through said membranes and chambers in a direction to cause the fructose to pass from said feed chamber through said high permeability coefficient membrane into a second chamber with said fructose being substantially retained in the second chamber, and (3) recovering a glucose enriched and a fructose enriched effluent from the separate chambers.

Abstract: A process for the removal of silica from an aqueous solution is disclosed in which the pH of the solution is adjusted to at least about 9.5 and then passed through a conventional electrodialysis cell to effect ionic transfer of the silica out of solution.

Abstract: An aqueous solution of a metal salt solution is converted to the corresponding acid by hydrogen ion substitution in a four compartment electrolytic cell containing three cation permselective membranes or barriers for defining the cell compartments. In one specific embodiment the salt solution initially treated in the intermediate compartment located adjacent to the cathode compartment is further treated by passing into the intermediate compartment located adjacent the anode compartment and thereafter removing the same as the final acid product. Such a flow arrangement prevents or reduces loss of hydrogen or citrate ions into the cathode compartment resulting in an increased acid yield with increased current efficiency.

Abstract: An aqueous solution of a metal salt solution is converted to the corresponding acid by hydrogen ion substitution in a four compartment electrolytic cell containing three cation permselective membranes or barriers for defining the cell compartments. In one specific embodiment the salt solution initially treated in the intermediate compartment located adjacent to the cathode compartment is further treated by passing into the intermediate compartment located adjacent the anode compartment and thereafter removing the same as the final acid product. Such a flow arrangement prevents or reduces loss of hydrogen or citrate ions into the cathode compartment resulting in an increased acid yield with increased current efficiency.

Abstract: A process is provided for removing ions from water which is passed through an ion depletion compartment of an electrodeionization apparatus. The electrodeionization apparatus contains an ion depletion compartment containing mixed ion exchange resin beads and an ion concentration compartment which may contain ion exchange resin beads in a given separation stage having an anode and a cathode. The anion resin beads and cation resin beads utilized each comprise beams of substantially uniform size. A second liquid is passed through the ion concentration compartment to collect ions under the influence of DC potential which pass from the depletion compartments into the concentration compartments through ion permeable membranes. The electrodeionization apparatus can be operated continuously since resin regeneration is not required.