Patent ID: 8183389

Claim:
A process for the treatment of an aqueous mixture comprising a dipolar aprotic compound which is selected from the group consisting of hexamethylphosphorous triamide (HMPT), dimethylsulfoxide (DMSO), 1-ethyl-2-pyrrolidone (NEP) and urea derivatives of the following formula: wherein R 1 , R 2 , R 3 and R 4 may each independently be H or a C 1 -C 4 alkyl group and wherein R 2 and R 3 may be part of a heterocyclic group, the process comprising: a) an adsorption step which comprises bringing the aqueous mixture into contact with a porous adsorbent, wherein the porous adsorbent is chosen such that the dipolar aprotic compound adsorbs to it more readily than water; and b) a desorption step which comprises bringing the porous adsorbent into contact with a desorbing agent which comprises methanol to thereby form a recovery solution comprising the desorbing agent and the dipolar aprotic compound.