Method for the purification of reclaimed aqueous N-methylmorpholine N-oxide solution

摘要

There is disclosed a method for purifying a used aqueous N-methylmorpholine N-oxide solution reclaimed from a spinning aqueous solution, which results from a coagulation solution into which a cellulose dope containing N-methylmorpholine N-oxide is extruded through a spinning die and from a washing solution for the coagulated cellulosic articles in manufacture processes for cellulose fibers or films, comprising adding an oxidant to the used aqueous N-methylmorpholine N-oxide solution to remove impurities therefrom through oxidation N-methylmorpholine into N-methylmorpholine N-oxide and break down of the chromophores of the impurities. Utterly distinguished from, conventional methods in the principle, the method is very simple and efficient as well as far superior to the conventional methods using ion exchange resin in the decoloration. In addition, it needs not suffer a loss of amine oxide as usual in the ion exchange resin. Further, the oxidant can achieve the decolorization without influence of concentration of amine oxides. The amine oxide decolorized by the oxidant may be used to prepare the cellulose dope without any more purification. Provided that sequential use of the oxidant and the resin or active carbon, there are brought about much higher efficiency as well as much purer aqueous amine oxide solution.