Process for separating a charged species from an aqueous system

A process for separating a charged species from an aqueous system, wherein the process comprises the following steps:

• (a) contacting a first aqueous system comprising the charged species at a first temperature with an ampholytic polymeric system comprising cationic and anionic groups, wherein the charged species is bonded to the ampholytic polymeric system;
• and
• (b) contacting the ampholytic polymeric system with a second aqueous system at a second temperature less than 60° C., wherein the charged species is released to the second aqueous system, and wherein the second temperature is higher than the first temperature;
• and wherein the ampholytic polymeric system is an interpenetrating network or a semi-interpenetrating network;
• the interpenetrating network or the semi-interpenetrating network comprising a cationic monomer and an anionic monomer, wherein the molar ratio of cationic monomers to anionic monomers is in the range of 5:1 to 1:5, the cationic monomers being vinyl or isopropenyl monomers containing a cationic form of a primary, secondary or tertiary alkyl or aryl amine, or of a nitrogen-containing heterocyclic aromatic compound, wherein the cationic monomer has the formula:
• CH2═C(R)—R′—NR1R2.R*X
• wherein:
• R is selected from the group consisting of H and CH3;
• R′ is absent, or an optionally functionalised spacer;
• R1 and R2 are independently selected from the group consisting of H, C1-12 linear or branched alkyl and C6-12 aryl;
• X is halogen or ½ SO4;
• and R* is H, C1-12 linear or branched alkyl, or C6-12 aryl, or a polymer or copolymer thereof;
• or
• wherein the cationic monomer has the formula:
• CH2═CRC(O)NH—R3—NR1R2.R*X
• wherein R1 and R2 are independently selected from the group consisting of H, C1-12 linear or branched alkyl and C6-12 aryl, R* is H, C1-12 linear or branched alkyl, or C6-12 aryl, R3 is C1-12 linear or branched alkyl, and X is halogen or ½ SO4.