REMOVAL OF SULPHATE FROM SOLVENTS USING ANION-EXCHANGE RESIN Russian patent published in 2021 - IPC B01D53/14 B01D53/18 B01D53/50 B01D53/77 B01D53/96 B01J41/00 

FIELD: chemical or physical processes.

SUBSTANCE: invention relates to selective removal of bivalent sulfur oxyanion (e.g., sulphate) from an aqueous solution. Method of selective removal and extraction of sulfur dioxide from sulfur dioxide-containing starting gas, wherein method includes: bringing the feeding gas stream containing the initial gas into contact with a buffered aqueous absorbing medium containing a salt of a polybasic carboxylic acid in a sulfur dioxide absorber, thereby absorbing sulfur dioxide from the feed gas stream with an absorbent medium and forming an exhaust gas from which sulfur dioxide is removed, and an absorption liquid enriched with sulfur dioxide, containing water absorbing medium and sulfur dioxide absorbed therein; heating the sulfur dioxide enriched with absorption liquid in a stripping apparatus of absorption liquid, in order to desorb sulfur dioxide from the absorption liquid enriched with sulfur dioxide, and thus a recovered aqueous absorbing medium and a sulfur dioxide enriched with sulfur dioxide are obtained; recirculated regenerated aqueous absorbing medium is directed to the sulfur dioxide absorber for further absorption of sulfur dioxide from the subsequent flow of the feed gas stream, where divalent sulfur oxyanion impurities are accumulated in the aqueous absorbing medium circulating between the stripping apparatus of the absorption liquid and the sulfur dioxide absorber; and bringing the feeding anion-exchange stream containing at least a portion of the aqueous absorbing medium circulating between the stripping apparatus of the absorption liquid and the sulfur dioxide absorber to contact with the anion-exchange resin, thereby selectively removing impurities of bivalent sulfur oxyanion from feed anion-exchange stream and obtaining treated aqueous absorbing medium, from which impurities are removed, and anion-exchange resin loaded with impurities, removed from feeding anion-exchange stream, where the feed anion-exchange stream is acidified until brought into contact with the anion-exchange resin in order to convert at least a portion of the salt of the polybasic carboxylic acid into the corresponding acid.

EFFECT: technical result is simplification of process of removal of sulphate impurities and reduced losses of absorbent.

26 cl, 10 dwg, 2 tbl