Abstract: A method for producing an aqueous solution of an aminocarboxylic acid from an aqueous solution of an alkali metal salt of the aminocarboxylic acid is disclosed. The first step of the method is to adjust the pH of the aqueous solution of the alkali metal salt of the aminocarboxylic acid to between about 1.0 and about 3.0. This is done by adding a monovalent inorganic acid to the aqueous solution of the alkali metal salt of the aminocarboxylic acid to form an aqueous feed solution containing protonated aminocarboxylic acid and an inorganic alkali salt having an inorganic anion and an alkali metal cation. The second step of the method is to pass the aqueous feed solution through at least one membrane using a diafiltration process to separate the aqueous feed solution into an aqueous permeate solution, containing the alkali metal cation, and an aqueous retentate solution containing the aminocarboxylic acid.

Abstract: A process for purifying propylene oxide containing an unacceptable quantity of a poly(propylene oxide) polymer contaminant having a molecular weight of at least about 50,000, comprising the step of filtering propylene oxide containing such polymer contaminant through one or more membranes to provide a propylene oxide product fraction having an acceptable quantity of poly(propylene oxide) polymer contaminant therein and a second fraction which is more highly concentrated in such polymer contaminant.