| 摘要 |
715,877. Purifying water. STANDARD OIL DEVELOPMENT CO. Oct. 29, 1952 [Dec. 4, 1951], No. 27229/52. Class 46 The generation of cation exchange material containing alkali metal cations removed from aqueous solution is effected by treating with sulphuric acid solution of amount substantially chemically equivalent to the exchangeable ions and with sulphurous acid calculated as an monobasic acid in an amount sufficient to substantially complete the regeneration, and treating the resulting solution containing bisulphite ions to remove and recover substantially the total bisulphite content. The exchange material may comprise coal, wood lignite or petroleum sludge each having been treated with sulphuric acid, also cation-exchange resins formed by condensing aldehydes such as formaldehyde with phenols, phenol-sulphonic acids or phenol-carboxyclic acids may be used. In operation cation exchange resin in a vessel 10 and which has been exhausted in converting sodium silicate entering through an inlet 12 into silica hydrosol leaving at an outlet 14 is regenerated by an upward flow of a mixture of sulphurous and sulphuric acids supplied through a duct 16. The spent and excess mixture is fed through a duct 26 to a still 28 where the excess sulphurous acid is vaporized by a heater 29 in an atmosphere of inert gas, e.g. nitrogen supplied through a duct 30 and is thereafter returned as sulphur dioxide through a duct 24 to the duct 16. Neutral solution comprising sodium sulphate leaves by a duct 32. |
