METHOD OF EXTRACTING PROPYLENE GLYCOL FROM AQUEOUS COMPOSITIONS Russian patent published in 2011 - IPC C07C31/20 C07C29/76 C07C43/13 C07C41/34 B01D1/26 B01D3/14 B01D61/00 

FIELD: chemistry.

SUBSTANCE: present invention relates to a method of extracting at least monopropylene glycol and/or dipropylene glycol from a mixture (C), containing water and said propylene glycols, involving (I) evaporation of the mixture in at least two evaporation and/or distillation steps while lowering working pressure of the evaporators and/or distillation columns to obtain a mixture (C') and a mixture (C"), where mixture (C") is further separated into a mixture (C-Ia), which contains at least 90 wt % water, a mixture (C-Ib) which contains less than 95 wt % water through reverse osmosis; (II) separation of mixture (C') obtained from (I) in at least one additional distillation step to obtain a mixture (C-I) which contains at least 70 wt % water, and a mixture (C-II) containing less than 30 wt % water, where mixture (C) contains 70-99.5 wt % water and 0.01-25 wt % of the said propylene glycols, mixture (C') contains 80-99.9 wt % water and 2.5-15 wt % of the said propylene glycols, and mixture (C") contains 90-99.99 wt % water and 0.01-0.5 wt % of the said propylene glycols.

EFFECT: high efficiency of extracting propylene glycol.

12 cl, 2 tbl, 2 ex