Patent GB-889656-A (GB)
Title: Ion-exchange assemblies and methods of treating liquids
IPC: B01J19/00
Filed: 1958-05-19
Abstract: <PICT:0889656/III/1> <PICT:0889656/III/2> <PICT:0889656/III/3> <PICT:0889656/III/4> <PICT:0889656/III/5> In the production of sulphuric acid from Na2SO4, or NaOH from NaCl, a liquid to be treated by ion-exchange is caused to flow along a water-insoluble elongated filamentary structure carrying ion-exchange groups at least on its surface, the filamentary structure being arranged either vertically or at an inclination to the horizontal and being suspended so that at least the main portion of the structure is free to expand or contract laterally under the influence of the liquid.  The filamentary structure may be a bundle of continuous filaments which may be untwisted or twisted around one another or around a core or may be bonded together by the inclusion of thermoplastic filaments or by means of an adhesive.  Alternatively, the filamentary structure may be a rope, strand, roving or sliver formed from staple fibres, or a woven, knitted or unwoven fabric.  It may comprise filaments having anion-exchange properties in association with filaments having cation-exchange properties, and the two kinds of filaments may be interspersed to enable anion-exchange and cation-exchange to proceed simultaneously.  The filaments may be composed of ion-exchange material, e.g. as described in Specification 858,864, or they may be of material having no ion-exchange effect which has been coated with an ion-exchange material or superficially treated to introduce ion-exchange groups.  Thus, cotton or regenerated cellulose may be reacted with 2-chlorethyldiethylamine to introduce amino groups into the surface, or it may be cyanoethylated by reaction with acrylonitrile and then hydrolysed to introduce carboxylic acid groups.  Fig. 1 shows an arrangement in which a filamentary tow or a web 2 is draped over a bar 5 and serves to treat a liquid supplied from a vessel 10 by a pipe 7, the treated liquid being collected in a vessel 13.  In Fig. 3, a number of filament bundles 2, some of which may have anion-exchange properties and the others cation-exchange properties, are supported beneath slots 26 in a manifold 25 to which the liquid to be treated is supplied.  In Fig. 5 a filamentary structure 2 is supported in a tube 29 to which inert gas may be supplied through a pipe 32, the liquid to be treated being supplied through a pipe 34.  In Fig. 7, a filament bundle 2 is supported from a bar 5 on an inclined tray 39.  In Fig. 9, two filament bundles 2 are arranged so that one is in use while the other is undergoing regeneration; liquid to be treated is supplied from a pipe 45 and regenerating liquid from a pipe 46, and by manipulation of the three-way valves 44, 48 either liquid may be directed on to either bundle, as desired.  The filamentary structure may also be an endless belt mounted, e.g. in a triangular circuit, so that the liquid to be treated flows by gravity down a part of the belt, and in this case a regenerating liquid may be applied to a part of the belt not traversed by the liquid to be treated, and a washing liquid may be applied to the belt between the liquid-treating stage and the regeneration stage; squeeze rolls may be provided at the end of each stage.  In the examples, use is made of filamentary structures prepared, as described in Specification 858,864, from a copolymer of 65% of acrylonitrile, 15% of butoxyethyl acrylate and 20% of methoxymethyl vinyl sulphide, which is treated with an aqueous-alcoholic solution of phosphoric acid and iodine at room temperature, dried and then cured at 150 DEG C. to effect cross-linking (resin A).  Resin A may then be treated with dimethylaminopropylamine and the product quaternized, e.g. with methyl iodide, to produce a strongly basic resin (resin B). Alternatively, resin A may be hydrolyzed with aqueous alcoholic caustic soda and converted into the hydrogen form (resin C) by treatment with dilute hydrochloric acid.  In Examples 3 and 6, hard water is treated with tows or fabrics of resins B and C, used simultaneously, and in Example 4 dilute sodium chloride solution is converted into sodium hydroxide solution by passage through a knitted sleeve of resin B.  In Example 5, a filament tow formed from a copolymer of 55% of acrylonitrile, 25% of butoxyethyl acrylate and 20% of methoxymethyl vinyl sulphide is cured in the same way as resin A and then reacted first with ethylene diamine and then with sodium bisulphite and formaldehyde; the product is used to convert a dilute sodium sulphate solution into dilute sulphuric acid.  Specifications 840,127, 840,900, 842,215, 845,367 and 867,545 also are referred to.ALSO:For use in ion-exchange processes (see Group I), cotton or regenerated cellulose in filamentary or fabric form may be reacted with 2-chlorethyldiethylamine to introduce amino groups into the surface, or it may be cyanoethylated by reaction with acrylonitrile and then hydrolyzed, to introduce carboxylic acid groups.