Abstract: The invention provides a process for the separation, by electrodialysis, of a mixed aqueous solution, containing an essential amino acid and a derivative of that acid as components therof, wherein one of said components is in charged form and the other of said components is in amphoteric form, into at least two separate product solutions, of acid and derivative respectively, of which at least one product solution contains highly pure product obtained at high quantitative yield, comprising providing an electrodialysis stack, continuously introducing a feed solution containing an essential amino acid and derivative thereof to be separated into feed cells of the stack, adjusting the flow rate and concentration of the solution and the electric current density applied to values adapted to create concentration polarization conditions adjacent to the membranes in the feed cell thereby accumulating a high local concentration of protons upon the surface of the anion exchange membranes, and a high local concentration o

Abstract: The invention provides a process for the separation, by electrodialysis, of a mixed aqueous solution containing a non-essential amino acid and a derivative of that acid in ionic form, into at least two separate product solutions of acid and derivative respectively, of which at least one solution contains highly pure product obtained at high quantitative yield, comprising providing an electrodialysis stack, continuously introducing a feed solution containing a non-essential amino acid and derivative thereof to be separated into feed cells of the stack, adjusting the flow rate and concentration of the solution and the electric current density applied to values adapted to create concentration polarization conditions adjacent to the membranes in the feed cells thereby accumulating a high local concentration of protons upon the surface of the anion exchange membranes, and a high local concentration of hydroxyl ions upon the cation exchange membranes and maintaining the pH of the bulk solution in the feed cells in

Abstract: According to the present invention there is provided an improved electrodialysis device comprising an electrodialysis stack with an anode compartment adjacent one end of the stack, a cathode compartment adjacent the other end of the stack, said electrode compartments being connected with each other by means of conduits, means being provided for circulating a slurry of carbon particles between the two electrode compartments. The slurry comprises finely powdered active carbon in an electrolyte, either by itself or in combination with finely powdered ion-exchange resin. The electrode compartments can be provided with inserts defining constrictions for the outflow of the slurry at the lower part of the inserts thus establishing a higher concentration of the particles at the lower part of the compartment. The invention further relates to an eletrodialysis process wherein a slurry of carbon particles is circulated between the electrode compartments.

Abstract: According to the present invention there is provided a novel type of membrane unit for use in electrodialysis comprising a heat-sealable frame framing and forming an integral entity with an electrodialysis membrane. The frame may be a regular frame, or a two-frame structure framing a single membrane. The invention further relates to electrodialysis devices such as stacks, bags, cells, spiral units and the like based on such membrane units, which are hermetically bonded by heat-sealing to similar units or to polymeric or other members.

Abstract: An electrodialysis device comprising a plurality of adjacent compartments through which there flow dialysate and brine, respectively, each dialysate compartment being separated from the adjoining two brine compartments by an anion-selective and by a cation-selective membrane, respectively, the two terminal compartments being connected to an anode and to a cathode of a current source, wherein in the space between the membranes there is provided a continuous anion conductive element and a continuous cation conductive element, in contact with each other, each of these consisting of a different kind of ion-exchange material, the anion selective material being in contact with the anion-selective membrane, the cation selective exchange material being in contact with the cation selective membrane, the electric resistance of said elements being lower than that of the dialysate, said elements providing a path for the different ions across a larger part of the distance between the membranes.

Abstract: A drug delivery preparation with controlled release time and rate, comprising a therapeutic agent being encapsulated in or coated by a solvent membrane, as well as a process for the manufacture thereof, are disclosed.