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 of hydroxyl ions upon the cation exchange membranes and maintaining the pH of the bulk solution in the feed cells in a range of between 4-8, irrespective of the isoelectric point of the amphoteric component, in order to adjust for pH changes of the bulk solution occurring due to unequal rates of water dissociation at the cation and anion exchange membranes.
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 a range of between 4-8, irrespective of the isoelectric point of the amino acid, in order to adjust for pH changes of the bulk solution occurring due to unequal rates of water dissociation at the cation and anion exchange membranes.
Abstract:
The invention provides a method for the performance of selective electrodialytic separation of a first group of charged ions from a solution containing other charged ions having the same sign and optionally the same valence as said first group comprising applying a current to an electrodialysis unit comprising at least one thin, dense, non-porous charged electrodialysis membrane made of water-insoluble hydrophobic polymeric material, containing covalently bound ionizable groups, wherein said membrane separates at least one diluting compartment from at least one concentrating compartment in said unit and wherein said membrane is in the form of a polymeric matrix optionally supported on a porous support and having a preselected dielectric constant and composition adapted to induce selective ion disassociation of said first group of charged ions whereby there is achieved a substantial ion migration of said selected ion group and its preferential transference across said membrane at a fraction larger than its relative concentration in said solution. The invention also provides a selective electrodialysis unit per carrying out said method.
Abstract:
A supported, mechanically stable bipolar membrane for electrodialysis having a cation-exchange layer on one side and an anion-exchange layer on the other side of a single sheet of woven fabric. The cation exchange layer is heterogeneous, the anion exchange layer is homogeneous and the two are interlocked. A process of making such bipolar membranes is described. The bipolar membrane may be fabricated into electrodialysis cells in which two membranes are joined along their edges.
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:
The present invention provides anion exchange membranes, processes for producing same and uses thereof. The anion exchange membranes according to embodiments of the present invention achieve a desirable combination of low resistance, high permselectivity and low degree of dimensional swelling. Anion exchange membranes according to embodiments of the present invention are also cost effective.
Abstract:
There is provided herein a membrane or film comprising one or more aromatic ionomers covalently crosslinked through aryl-aryl (—Ar—Ar—), aryl-ether-aryl (—Ar—O—Ar—), aryl-sulfide-aryl (—Ar—S—Ar—), aryl-sulfone-aryl bonds, or any combination thereof, wherein said one or more aromatic ionomers further comprises at least one electron withdrawing group adapted to improve oxidant resistance of said membrane or film.
Abstract:
There are provided herein selective membranes, such as composite membranes, and/or films and processes for their preparation. The membranes and/or films have a given morphology which may be stabilized, for example against swelling and chemical degradation, by covalent crosslinking and optionally, in addition, by hydrophobization. There is provided a membrane and/or film and a process for the preparation thereof, the membrane and/or film include an ionomer and/or polyelectrolyte crosslinked through aryl-aryl (—Ar—Ar—), aryl-ether-aryl (—Ar—O—Ar—) and/or aryl-sulfide-aryl (—Ar—S—Ar—) bonds.
Abstract:
The invention provides a polymeric netting for use as an ion-conducting ser in an electrodialysis stack having charged groups incorporated in a in polymeric coating applied thereto, imparting to the spacer an average ion exchange capacity of at least 0.25 meq/gr.
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.