Uptake of heavy metals from synthetic aqueous solutions using modified PEI-silica gels

The decontamination of synthetic Pb(II), Zn(II), Cd(II), Ni(II) solutions was investigated, using silica gels chemically modified with poly(ethyleneimine) (PEI) as sorbents. Two families of sorbents, i.e. silica/PEI and crosslinked silica/PEI, were prepared and characterized. Then the removal of metal ions from synthetic aqueous solutions was studied by static tests. They revealed that the sorption capacities depend on the pH, the initial concentration and to some extent on the nature of the metal. The recovery of the metal cations from the saturated sorbents was possible with diluted acid, only for the crosslinked supports. In this case, the regeneration and reuse without sorption decrease, was demonstrated. The presence of other cations (as Na(+), Ca(2+)) and metals does not affect the sorption capacities.