Abstract: Described is a process for preparing concentrated solutions or suspensions of anionic organic compounds which comprises a) acidifying an aqueous solution or suspension of an anionic organic compound containing salts and/or impurities to a pH of 4.5 or less, if the pH is above this value, so that b) the anionic organic compound is water-insoluble and precipitates in the form of the free acid, c) bringing the suspension to a salt content below 2% by weight, based on the total weight of the retentate, by means of ultrafiltration with a membrane having pore diameters of from 0.001 to 0.02 ?m, and d) optionally washing out the salts with water having a pH below 4,5, e) optionally carrying out acid-free washing with water thereafter, and then f) concentrating, so that the amount of anionic organic compound is 5-50% by weight, and g) if desired, bringing the anionic organic compound into solution by adding an appropriate base.

Abstract: A process for the preparation of concentrated solutions or suspensions of anionic organic compounds is described, which process comprises a) acidifying an aqueous solution or dispersion of an anionic organic compound that comprises salts and/or impurities to a pH of 4.5 or less, if the pH is above that value, so that the anionic organic compound becomes insoluble in water and precipitates out in the form of the free acid, b) bringing the suspension obtained from the previous step to a salt content below 2% by weight, based on the total weight of retentate, by means of ultra-filtration with a ceramic membrane or an acid-resistant organic membrane having a pore size of from 1 to 20 nm, and c) optionally washing out of the salts with water at a pH of less than 4.

Abstract: Described is a process for preparing concentrated solutions or suspensions of anionic organic compounds which comprises a) acidifying an aqueous solution or suspension of an anionic organic compound containing salts and/or impurities to a pH of 4.5 or less, if the pH is above this value, so that b) the anionic organic compound is water-insoluble and precipitates in the form of the free acid, c) bringing the suspension to a salt content below 2% by weight, based on the total weight of the retentate, by means of ultrafiltration with a membrane having pore diameters of from 0.001 to 0.02 &mgr;m, and d) optionally washing out the salts with water having a pH below 4,5, e) optionally carrying out acid-free washing with water thereafter, and then f) concentrating, so that the amount of anionic organic compound is 5-50% by weight, and g) if desired, bringing the anionic organic compound into solution by adding an appropriate base.