Method for producing N-phosphonomethylglycine

Abstract

The present invention relates to a process for the recovery of N-phosphonomethylglycine from an aqueous mixture which contains N-phosphonomethylglycine, ammonium halides, and alkali metal or alkaline earth metal halides and optionally organic impurities in dissolved form, where (a) the pH of the mixture is adjusted to a value in the range from 2 to 8, (b) a separation of the mixture on a selective nanofiltration membrane is performed, a retentate which is richer in N-phosphonomethylglycine and poorer in halides and a permeate which is richer in halides and poorer in N-phosphonomethylglycine being obtained, and (c) the N-phosphonomethylglycine is recovered from the retentate. The process according to the invention makes possible the recovery of the N-phosphonomethylglycine with simultaneous separation of the halide salts.

Dependencies are inferred from the claim text.