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US 4,045,352 AGranted
Ion-exchange hollow fibers
AssigneeCalifornia Institute of Technology
InventorsAlan Rembaum, Shiao-Ping S. Yen, Elias Klein
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AssigneeCalifornia Institute of Technology
InventorsAlan Rembaum, Shiao-Ping S. Yen, Elias Klein
Estimating the term…
An ion-exchange hollow fiber is prepared by introducing into the wall of the fiber polymerizable liquid monomers, and polymerizing the monomers therein to form solid, insoluble, cross-linked, ion-exchange resin particles which embed in the wall of the fiber. Excess particles blocking the central passage or bore of the fiber are removed by forcing liquid through the fiber. The fibers have high ion-exchange capacity, a practical wall permeability and good mechanical strength even with very thin wall dimensions. Experimental investigation of bundles of ion-exchange hollow fibers attached to a header assembly have shown the fiber to be very efficient in removing counterions from solution.
An ion-exchange medium comprising a hollow, annular, thin-wall, microporous fiber of a synthetic, organic, thermoplastic resin having pores having an average diameter less than 1000 angstroms which join to form a path across the wall of the fiber and having solid particles of a cross-linked, insoluble ion-exchange resin formed in situ in said pores from ion-exchange reactants of a molecular weight capable of impregnating the pores having a diameter smaller than the pore diameter and having an even distribution of fixed charge embedded and constrained within said pores without blocking said pores of said path such that said medium has a hydraulic permeability of from 1 to 100 .times. 10.sup.-5 mil/cm.sup.2 sec atm.
Dependencies are inferred from the claim text.
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Dialysis ; Membrane extraction: dialysis
Apparatus in general for separation processes using semi-permeable membranes: hollow fibre modules
Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes…:…
Ion-exchange processes in general; Apparatus therefor: granulation; Incorporation of ion-exchangers in a matrix; Mixing with inert materials
Term ended 30 Aug 1994 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
1. Field of the Invention
The present invention relates to ion-exchange materials and, more particularly, this invention relates to novel ion-exchange hollow fibers and methods of forming and using such fibers.
2. History of the Prior Art
These and other advantages of the invention will become apparent as the invention becomes better understood by reference to the following detailed description when considered in conjunction with the following drawings.
FIG. 1 is a cross-sectional view of a single hollow fiber;
FIG. 2 is a schematic view of a hollow fiber tube assembly;
Referring now to FIG. 1, a hollow fiber 10 has an annular configuration, typically cylindrical. The wall 12 of the fiber 10 includes an outer skin 14 and an inner skin 16. The wall 12 contains microvoids or pores 18 which join across the wall to form a path or channel providing microporosity or semipermeability characteristics to the fiber. Particles 20 of ion-exchange resin are formed within and embedded within the pores without blocking the pores in accordance with the invention.
The dimensions of the fibers are selected depending on the use and capacity of the end device. Length of the fibers is the least important dimension and is dependent on the amount of ion to be removed, the flux rate through the wall, the flow rate of solution, the number of fibers in a bundle, and the practical length of the unit. The wall thickness, permeability and ion-exchange capacity are the most influential factors in the performance and effectiveness of ion-exchange hollow fibers.
The wall thickness is preferably as thin as practical under the circumstances and is preferably as low as 10 microns, typically from 20 to 300 microns, preferably 30-100 microns. The inside diameter is always maintained as low as possible to maximize available surface area. The inside diameter typically ranges from 50 to 1000 microns.