Patent GB-490799-A (GB)
Title: Improvements relating to the deacidification of liquids
IPC: C02F5/00
Filed: 1937-09-08
Abstract: An aniline black or other basic dyestuff which is insoluble in water and in aqueous acids or alkalies and which forms salts which are similarly insoluble and are not hydrolysed by the acidic liquid under the conditions of the treatment is used, preferably in the form of a granular filtering medium, for de-acidifying aqueous acidic liquids. Such a medium is obtainable, for example, by drying, preferably at room temperature, and pulverizing the sludge obtained by the oxidation of an aromatic amine, e.g. aniline, o-toluidine, o-chloraniline, b -naphthylamine, m-phenylenediamine or an aminophenol, the oxidation being advantageously effected in dilute solution in presence of a protective colloid such as a water-soluble albumen or glue or a sulphonated product such as turkey red oil or "Igepone" (Registered Trade Mark) and in presence of an oxidation catalyst such as an iron compound or an aminophenol.  Alternatively or additionally the desired physical properties of the dyestuff preparation may be attained by incorporating in it a binding agent, such as a cellulose derivative or an albumen, or the dyestuff may be produced in presence of or deposited upon a carrier body such as carbon, cellulose, a ceramic mass or pumice, or threads, e.g. of wool, upon which the dyestuff has been produced, may be used.  When the absorptive capacity of the dyestuff becomes exhausted it is regenerated by treatment with an aqueous solution of an alkali such as ammonia, sodium carbonate or bicarbonate or a caustic alkali.ALSO:Aqueous acidic liquids, especially such as are produced by treating water containing salts with a hydrogen ion exchange material, are de-acidified by subjecting them to the action of a basic dyestuff which is insoluble in water and in aqueous acids and alkalies and which forms salts which are similarly insoluble and are not hydrolysed by the acidic liquid under the conditions of the treatment.  Specified dyestuffs are the compounds of the aniline black type obtainable by oxidation of aromatic amines such as aniline, o-toluidine, o-chloraniline, b -naphthylamine, m-phenylenediamine and aminophenols.  The acidic liquid is preferably filtered through the granular dyestuff material obtainable, for example, by drying, preferably at room temperature, and pulverizing the sludge obtained by the oxidation of the amines, such oxidation being advantageously effected in dilute solution in presence of a protective colloid such as a water-soluble albumen or glue or a sulphonated product such as turkey red oil or "Igepone" (Registered Trade Mark) and in presence of an oxidation catalyst such as an iron compound or an aminophenol.  Alternatively or additionally the desired physical properties of the dyestuff preparation may be attained by incorporating in it a binding agent, such as a cellulose derivative or an albumen, or the dyestuff may be produced in presence of or deposited upon a carrier body such as carbon, cellulose, a ceramic mass or pumice, or threads, e.g. of wool, upon which the dyestuff has been produced may be employed.  When the absorptive capacity of the dyestuff becomes exhausted it is regenerated by treatment with an aqueous solution of an alkali such as ammonia, sodium carbonate or bicarbonate or a caustic alkali.