Column performance of ion exchange resins with aminophosphonate functional groups for elimination of heavy metals

The column dynamics of the exchange of heavy metals in multicomponent systems with Cu2+, Ni2+, Cd2+, Zn2+, Ca2+, Na+, and NH4+ ions has been studied. The ion exchangers applied were two commercially available chelating ion exchange resins (Purolite S 940 and S 950) and two experimental resins (Purolite D 3342 and D 3343), all with aminophosphonate functional groups. Experiments comprised pure systems with two, three and four metal species and with simulated industrial wastewaters. Calculation of multicomponent equilibria was based on the surface complexation theory, Prediction of the column performance used either a staged approach or the numerical solution of the differential Column balance. In the latter case simplified approaches for description of sorption kinetics for predominant film or particle diffusion were applied. Kinetic parameters were deduced from simple binary experiments. The prediction of the column performance by means of the differential Column balance led to a partly very satisfactory agreement with experimental data.