| abstract |
For the purification of aqueous solutions of N-methylmorpholine-N-oxide (NMMO), in particular spin bath solutions, which are obtained in the manufacture of cellulosic products, by which process the solutions to be cleaned are brought into contact with an anion exchanger and the cleaned solutions are separated from the anion exchanger. the purification is carried out in a one-step process using an anion exchanger which, as functional groups, exclusively contains quaternary tetraalkylammonium groups of the formulas -CH₂-N ⊕ (CH₃) ₃X ⊖ or -CH₂-N ⊕ [(CH₃) ₂ (CH₂OH)] X ⊖ has, wherein X ⊖ represents the anion of an inorganic or organic acid, whereupon the anion exchanger is regenerated with an aqueous acidic solution. |