PROCESS FOR THE SEPARATION OF SODIUM SULPHATE FROM AQUEOUS SOLUTIONS CONTAINING SODIUM SULFATE AND LESS THAN 2 BY WEIGHT OF ANIONIC OR CATIONIC CHLORIDE DYES, AS WELL AS DYE SOLUTIONS SO OBTAINED

摘要

1. A process for separating sodium sulfate from aqueous solutions, containing sodium sulfate and less than 2% by weight of chloride, of anionic or cationic dyestuffs, in particular water-soluble dyestuffs of the general formula (1) see diagramm : EP0158233,P25,F2 in which F is the radical of a dyestuff chromophore of an anthraquinone dyestuff, of a monoazo dyestuff, of a disazo dyestuff, of a trisazo dyestuff or of a phthalocyanine dyestuff or of a copper, chromium, cobalt, nickel or iron complex dyestuff of a monoazo, disazo or trisazo dyestuff or phthalocyanine dyestuff, or of a formazan, copper-formazan or nickel-formazan dyestuff, M is a hydrogen atom or preferably an alkali metal, k is zero, 1, 2, 3 or 4 and m is zero, 1, 2, 3 or 4 the sum of (k + m) being a number of at least 1, n is 1, 2 or 3, Z is a fiber-reactive monochlorotriazine radical or a fiber-reactive group of the formula (2b), (2c), (2d) or (2e) see diagramm : EP0158233,P25,F3 see diagramm : EP0158233,P25,F4 see diagramm : EP0158233,P25,F5 see diagramm : EP0158233,P25,F6 in which G is a methylene or ethylene group and R is an alkyl group of 1 to 4 carbon atoms, p stands for the number zero or 1 and Y is an acetyloxy group, a phosphato group, a thiosulfato group or a sulfato group or a chlorine or bromine atom, and in which the fiber-reactive groups Z, insofar as in accordance with n being equal to 2 or 3 they are bonded to F twice of three times, can have meanings which are identical to or different from one another, the indicated sulfo groups cannot only be bonded to aromatic and aliphatic carbon atoms of F but can also be part of the fiber-reactive monochlorotriazine radical, the indicated sulfato groups cannot only be bonded to aliphatic carbon atoms of F but can also be part of the fiber-reactive group of the formula (2c) or (2e) and/or the fiber/reactive monochlorotriazine radical, which comprises cooling down the solution to a temperature between + 5 degrees C and - 15 degrees C and separating off the precipitated sodium sulfate decahydrate.