Complexation reactions in a heterogeneous system

A new resin incorporating the N-(hydroxymethyl)-thioamide group anchored on macroreticular acrylonitrile-divinylbenzene copolymer was described. The dissociation constant of the functional group of this resin, pK_a was 6.56. Elementary analysis, infrared spectra and some chemical reactions were used for characterization. The optimum pH for Ag(I), Cd(II), Co(II), Cu(II), Fe(III), Hg(II), Ni(II), Pb(II) and Zn(II) ion complexation and the stability constants of cadmium, copper and silver resin complexes were also determined. The affinity of these metal ions toward the synthesized resin was in the order of Hg(II) > Fe(III) > Pb(II) > Cu(II) > Cd(II) > Co(II) > Ni(II) ≥ Zn(II) on the basis of pH _{1 2} which is the pH for 50% sorption of metal ions on the resin. All the cations in the resin-metal kinetics study showed high exchange rates except that for iron which required seven min.