Lenzing Aktiengesellschaft

Stephan Astegger

Dieter Eichinger

Heinrich Firgo

Karin Weinzierl

Stefan Zikeli

Johann Manner

Bernd Wolschner

Peter Hinterholzer

Raimund Jurkovic

Heinz Falk

Korger Dietmar

Gunter Teubl

Dietmar Korger

Peter Harfmann

The invention is concerned with a process for the destruction of N-nitrosomorpholine in an aqueous solution containing N-nitrosomorpholine and a peroxidic oxidant, characterized in that said aqueous solution is exposed to ultraviolet radiation having a wavelength of substantially 254 nm.

Process for the regeneration of an aqueous process liquid of the

Amine-oxides of the general formula: ##STR1## wherein R.sub.1 and R.sub.2 are alkyl groups with 1 to 4 C-atoms, R.sub.3 is hydrogen, a hydroxyl group or an alkoxy group with 1 to 4 C-atoms and m and n are whole numbers which fulfil the conditions 1.ltoreq.m.ltoreq.8 and 0.ltoreq.n.ltoreq.4 respectively, with the proviso that n is not 0 if R.sub.3 is a hydroxyl group or an alkoxy group, can be used with advantage for the preparation of mouldable or spinnable cellulose solutions which have a reduced tendency to crystallise.

Amine-oxides

Shaped cellulosic bodies and especially cellulosic fibers or filaments are produced by precipitating cellulose from a solution containing cellulose and NMMO. To allow elevated concentrations of NMMO in the precipitating bath without detriment to the properties of the fibers or filaments produced, the temperature of the precipitating bath is held at most at 0.degree. C.

Method of producing shaped cellulosic articles

A solution of cellulose in water and N-methylmorpholine-N-oxide (NMMO) containing 2 to 44% by weight cellulose is stabilized at 0.01 to 1%, preferably 0.1% H.sub.2 O.sub.2 and 0.01 to 2%, preferably 0.1% of an H.sub.2 O.sub.2 stabilizer, preferably oxalic acid or a salt thereof during formation of the solution and during heating to prevent discoloration of the cellulose and reduce the composition of NMMO.

Cellulose solution in water and NMMO

For the removal of water from dilute aqueous solution of NMMO, N-methylmorpholine or morpholine or mixtures thereof, the solution is subjected to reverse osmosis at a pressure in excess of the osmotic pressure and probably around 40 bar and a temperature of 25.degree. C. to 75.degree. C. to form a retentate containing the amines and a permeate which is practically free from the amines. The permeate can be used as process water while the retentate can be worked up to NMMO for reuse in the cellulose solubilization process.

Method of removing water from a dilute solution of

There is disclosed a process for purifying aqueous solutions of N-methyl-morpholine N-oxide (NMMO), such as spinning bath solutions incurred in the production of cellulose products, in which process the solutions to be purified are contacted with an anion exchanger and the purified solutions are separated from the anion exchanger. The process is carried out in one step and the anion exchanger, as functional groups, exclusively contains quaternary tetraalkylammonium groups of the formulae

Process for purifying an aqueous solution of N-methyl-morpholine N-oxide

There is disclosed a method of removing amines from aqueous solutions thereof, in particular from waste waters obtained in cellulose processing. The aqueous amine solutions are contacted with a cation exchanger whose anchor groups consist of carboxyl groups, in order to charge the cation exchanger with the amines. The charged cation exchanger is treated with an aqueous solution of a weak acid having a pK.sub.a larger than 3.0 in order to elute the amines. The eluate is processed by way of distillation, wherein a portion of the weak acid is separated from the amines and reclaimed, if desired. The method according to the invention offers a simple and cheap way of disposing amine-containing waste waters.

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Vocklabruck, Austria

Stephan Astegger