a method for the removal of pollutant ions from an aqueous solution in which they are contained , which method includes the steps of : i ) contacting the solution to be treated with particles of a composite magnetic resin which includes magnetic particles embedded in an organic polymeric matrix which either contains , or has attached thereto sites which are selective for the pollutant ions in the presence of other ions it is not desired to remove ; ii ) separating by magnetic filtration the composite magnetic resin particles from the solution ; iii ) subjecting the separated composite magnetic resin particles to regeneration using an appropriate regenerant solution ; iv ) separating the regenerated composite magnetic resin particles from the regenerant solution ; and v ) recycling the separated composite magnetic resin particles to step of the method .