Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Ion-exchange polymer or process of preparing
Patent
1982-09-27
1984-05-29
Schofer, Joseph L.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Ion-exchange polymer or process of preparing
521 34, B01J 3918, B01J 4300
Patent
active
044515812
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to thermally regenerable ion-exchange resins and more especially it relates to such resins of the composite amphoteric type.
It is known that saline solutions may be demineralized at least in part by treating them with resinous material capable of acting as an ion-exchange material. One such method whereby saline solutions may be demineralized is one in which the resinous material is a thermally regenerable resin. Processes in which such resins are used are for example Australian Pat. Nos. 274,029 and 434,130.
BACKGROUND ART
One useful class of thermally regenerable ion-exchange resins suitable for demineralizing saline solutions is a class comprising composite amphoteric resins containing particles of both an acidic ion exchange polymeric component and a basic ion exchange polymeric component. A particularly useful class of composite amphoteric resins is the class comprising discrete acidic and basic domains grouped together in a particle or bead of essentially spherical form, with a diameter in a range from about 300 to 1200 microns. From within the above class of resins an effective subclass is one in which the resins are known as "active-matrix" resins. By the term "active-matrix" resins is meant resins obtained by a process in which two polymer precursors, such as monomers, are polymerized to give a resin in which the matrix is a mosaic of both the acidic polymer component and the basic polymeric component.
It will be appreciated that such an active-matrix may be formed by the simultaneous polymerization of both monomers. In instances where the rates of polymerization of the monomers are different then the matrix is formed, for example, by polymerizing a slowly polymerizing acidic monomer around particles of a faster polymerizing basic polymer or vice versa. In a variation of the above methods of manufacture such active-matrix resins may be made by polymerizing a monomer `X`, in the presence of a preformed polymer `Y`, which is, for example, in particulate or celled form and thereby encapsulating the preformed polymer `Y` particles in a matrix derived from the in situ polymerization of the monomeric component `X`.
Alternatively porous particles of preformed polymer `A` may be impregnated with a monomer `B` which is then polymerized within the `A` particles. In this instance the matrix, or continuous, phase will be provided by the preformed `A` polymer in contradistinction to the type described above in which the preformed `Y` polymer particles provide the discontinuous phase.
The active-matrix resins referred to herein are distinct from the so-called "plum pudding" resins described in the specification of Australian Pat. No. 434,130 and which comprise composite ion-exchange resins in particulate form and contain discrete particles of acidic and basic polymeric ion-exchange materials dispersed in an inert matrix of water insoluble polymeric materials.
The useful operating life of both "active-matrix" and "plum-pudding" resins is dependent upon the vulnerability of the resins to degradation by oxidation. The basic polymer component is particularly susceptible to oxidation, especially during the regeneration stage which involves treatment of the loaded resin with a hot, saline, solution. Prevention of such oxidation involves further operations which are both inconvenient and costly. For example the oxygen can be removed from the feed waters by chemical dosing or vacuum deaeration. Chemical dosing generally involves the addition of sodium sulphite. It is generally necessary to deoxygenate both the cold water feed and the hot regenerant feed because of the high level of sensitivity of the known systems to oxygen.
It is an object of the present invention to provide improved thermally regenerable ion exchange resins of the composite amphoteric type that are resistant to oxygen and therefore avoid the necessity for these operations.
DISCLOSURE OF INVENTION
We have now found that thermally regenerable amphoteric ion exchange resins having a high ion exchange capaci
REFERENCES:
patent: 3205184 (1965-09-01), Hatch
patent: 3706707 (1972-12-01), Vandenburg
Bolto Brian A.
Jackson Mervyn B.
Commonwealth Scientific and Industrial Research Organization
ICI Australia Ltd.
Kulkosky Peter F.
Schofer Joseph L.
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