PURPOSE: To provide a novel monomer which is more easily accessible than an aromatic polyether and polymerizable at a low oxidation potential.

CONSTITUTION: A monomer having at least three ether units and pyrrole or thiophene units and characterized by that respective heterocyclic compds. are connected to the terminal part of a polyether chain through the C-atoms at the 3,3'-positions of these heterocycles or, especially, through N-atoms in the pyrrole groups and many 2,2'-positions of these heterocycles are substituted with easily removable groups (e.g. protective groups) free to all of substitutions is a compd. for example, represented by formula I (m; 3-5) and formula II (wherein X is NH or S; and q' and q'' are each 1 or 2). A polymer is formed on a support material based on carbon being in contact with the anode of an electrolytic cell electrically by the electrical precipitation from an electrolyte containing salts forming non-oxidative anions along with the monomer. The polymer is used in the separation or recovery of transition metal, zinc, cadmium or silver ions contained in a soln. in contact therewith.