Ion-exchange processes M(II) → Fe(III) and Fe(III) → M(II) in metal hexacyanoferrate(II) gelatin-immobilized matrices (M = Mn, Co, Ni, Cu, Zn, Cd)

Ion-exchange reactions M2+ --> Fe3+ and Fe3+ --> M2+ (M = Mn, Co, Ni, Cu, Zn, Cd) were studied in metal(II) hexacyanoferrate(II) gelatin-immobilized matrices M-2[Fe(CN)(6)] in contact with aqueous FeCl3 solutions and Fe-4[Fe(CN)(6)](3) in contact with a ueous MCl2 solutions. It was shown that in both cases, M2+ was replaced by Fe3+ and Fe3+ was replaced by M2+ to some extent, but no complete replacement was observed in the M-2[Fe(CN)(6)]-FeCl3 or Fe-4[Fe(CN)(6)](3)-MCl2 systems under study. No electrophilic substitution Fe3+ Mn2+ was found to occur in any noticeable degree during the contact of Fe-4[Fe(CN)(6)](3) with aqueous MnCl2 solutions even when this contact occurred for 1 h and longer.