PL8745B1 - Method of cleaning chemicals. - Google Patents

Description

The chemicals used in the manufacture of products containing active oxygen must, as is well known, be very pure. Even very slight impurities, acting catalytically, break down certain compounds and reduce the yield and durability of the products obtained. The chemicals in question must therefore be as pure as possible and free, in particular, from catalytically active additives. For example, in the production of perborates and percarbonates, the compounds used in their production, so borax, soda and calcined soda must be as pure as possible, especially when the production of the above-mentioned products is carried out by electrolysis. Likewise, in the production of hydrogen peroxide, persulfates, and perphosphates, the oxygen-supplying chemicals must be very thoroughly cleaned to be free of catalysts. Recrystallization is usually used for purification. However, experience has shown that the oxygen yield and product stability are deteriorated by even such small admixtures (impurities), the existence of which cannot be practically demonstrated. For example, even small amounts of heavy metal salts normally contained in tap water, and even distilled water, have a significant influence. These are mainly manganese, copper and extremely small amounts of platinum. Trials have shown that these slight admixtures of catalysts can be removed by treating the solutions of the compounds to be purified with silica gel, which is likely to absorb the catalysts mentioned. . For example, it is sufficient if the borax or soda solution (after separating from it those quantities of heavy metal compounds which can be removed) is boiled once more before crystallizing with powdered silica gel, in this case, for example, 2 kg of gel per 1 m3 of solution. The salt crystallized from such a processed solution and transformed into an appropriate excipient gives the greatest yield, and the obtained product is very stable. Mixing the solutions with the gel can also take place in the cold, but the process takes longer then. Cold processing is used when the said chemicals are not separated from the solutions, but are further processed directly in the form of solutions. In this way, for example, the preparation of sodium perborate takes place by adding hydrogen peroxide to a sodium metalloborate solution. Silica gel is understood to mean a coarser or finer granular mass of pure silicic acid (see, for example, Meyer Zeitschrift fur angew Chemie, vol. 37, yearbook). 1924, pages 36 and 209 and U.S. Patent No. 1,297,724). The spent silica gel can be reused after washing and regeneration with acid and heating. PL

Claims (2)

Patent claims. 1. A method of purifying chemicals used in the manufacture of products containing active oxygen, characterized by the fact that the chemicals in the solutions are treated with an appropriate amount of silica gel. 2. A method according to claim 1, characterized in that the chemical solution is boiled in the presence of powdered silica gel, and the purely extracted solution is then crystallized. H e n k e 1 & Cie. G. m. B. H. Zastepca: Dr. inz. M. Kryzan, patent attorney. Print by L. Boguslawski, Warsaw. PL