GB576969A - Improvements relating to the purification of saline liquids - Google Patents

Abstract

576,969. Purifying liquids; filtering media. PERMUTIT CO., Ltd., PEMBERTON, R. T., and HOLMES, E. L. Dec. 22, 1941, Nos. 16516/41, 16580/41 and 1627/42. [Classes 46 and 111] [Also in Group III] Saline liquids, particularly sea water, are agitated, preferably by shaking, with a silver base-exchanger to remove chlorine ions and other anions which form insoluble salts with the silver that is exchanged. Anions giving rise to insoluble silver salts may also be removed by including other materials which will form insoluble salts with, or absorb, the anions, e.g., sulphate ions may also be removed by including a barium compound, such as barium chloride or a barium base-exchanger, or by using a silver and barium base-exchanger. The latter may be prepared by treating a silver base-exchanger with a limited quantity of a barium salt solution so that about one-fourth of the silver is exchanged for barium. In the treatment of urine, any phosphate ions are removed by the silver material and urea and other organic constituents by means of activated carbon, the liquid being subsequently passed through a bed of mixed cation- and anion-exchangers, as described in Specification 553,233, to remove nitrates or other soluble silver salts. Substances having basic reactions may also be removed by including a hydrogen-ion exchanger. The latter may be constituted by an organic silver base-exchanger having mobile hydrogen ions but, preferably, a separate hydrogen-ion exchanger is mixed with the other materials and compressed into pellets or tablets which are disrupted by the swelling of the hydrogenion exchanger on coming into contact with water. The cation-exchangers may be organic, e.g., formed by treating sulphonated coal or resins, but are, preferably, silver or barium aluminium silicates, dehydrated as described in Specification 576,971. A low silicate content improves the exchange capacity of the silver material and a higher content than that of the barium material and the exchange capacity decreases with increasing particle size. The treated liquid is preferably filtered through a filter paper or pad, which may be composed of cellulosic fibres reinforced with asbestos fibres. If activated carbon be incorporated in the filter, it is unnecessary to use a bed of mixed exchangers. A filter aid, e.g., finelydivided activated carbon, may be added to the mixture. The treatment may be effected in a container as described in Specification 576,970. Specification 402,953 also is referred to. The first Provisional Specification describes also the use of aluminium compounds, e.g., activated alumina, for removing phosphate ions.