Method for anion-exchange adsorption and anion-exchangers

Abstract

A method for the removal of a substance carrying a negative charge and being present in an aqueous liquid (I). The method comprises the steps of: (i) contacting the liquid with a matrix carrying a plurality of ligands comprising a positively charged structure and a hydrophobic structure, and (ii) desorbing the substance. The characterizing feature is that (I) each of said ligands together with a spacer has the formula: --SP---[Ar-R1-N<+>(R2R3R4)] where (A) [Ar-R1-N<+>(R2R3R4)] represents a ligand a) Ar is an aromatic ring, b) R1 is [(L)nR'1]m where n and m are integers selected amongst zero or 1; L is amino nitrogen, ether oxygen or thioether sulphur; R'1 is a linker selected among 1) hydrocarbon groups; 2) -C(=NH)-; c) R2-4 are selected among hydrogen and alkyls; (B) SP is a spacer providing a carbon or a heteroatom directly attached to Ar-R1-N<+>(R2R3R4); (C)--- represents that SP replaces a hydrogen in (Ar-R1-N<+>(R2R3R4); (D)-- represents binding to the matrix; and (II) desorption. There is also described (a) anion-exchangerrs having high breakthrough capacities, (b) a screening method and (c) a desalting protocol.

Description

[0001] The present invention relates a method for the removal of a compound (=substance) carrying a negative charge from an aqueous liquid (I). The method comprises the steps of[0002] i) contacting the liquid with an anion-exchanger that comprises a base matrix carrying a plurality of mixed mode anion-exchange ligands comprising (a) a positively charged structure and (b) a hydrophobic structure under conditions permitting binding between the ligands and the substance, and[0003] ii) desorbing said substance from said matrix by the use of a liquid (II).[0004] The invention also relates to novel anion-exchangers in which there are anion-exchange ligands comprising both a hydrophobic structure and a positively charged structure.[0005] The terms "carrying a negative charge" and "negatively charged" mean that the substance carries one or more negative charges and / or has a negative net charge.[0006] The terms "mixed mode anion-exchanger ligand" and "bimodal anion-exchanger ligand", in the ...

AI Technical Summary

Benefits of technology

[0028] b) to provide anion-exchange media that can have a reduced ligand content while retaining a sufficient capacity to bind target substances;

[0156] Desorption may also be assisted by adjusting the polarity of liquid (II) to a value lower than the polarity of the adsorption liquid (I). This may be accomplished by including a water-miscible and / or less hydrophilic organic solvent in liquid II. Examples of such solvents are acetone, methanol, ethanol, propanols, butanols, dimethyl sulfoxide, dimethyl formamide, acrylonitrile etc. A decrease in polarity of aqueous liquid II (compared to aqueous liquid I) is likely to assist in desorption and thus also reduce the ionic strength needed for release of the substance from the matrix.

Problems solved by technology

None of the methodologies in these three articles describe successful desorption processes under anion-exchange conditions.

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