(749d) Ion-Imprinted Chitosan Hydrogels for Recoverying Ag(I)

CS hydrogels were synthesized via a phase inversion method, during which the samples were cross linked with GLA and imprinted with various mass fraction of sliver salt. The salt was converted to silver oxides and Ag and then embedded to the polymer matrix to form selective cavities.  The molecular-imprinted hydrogels were obtained after chemical washing, rinsing, and drying.

Adsorption experiments were conducted in batch modes with Ag concentration ranging from 1 ppm to 200 ppm. It was found that,  A high mass ratio of Ag(I) imprinted hydrogel sample, i.e.75 mg-AgNO3/g-dry CS, presents a much improved adsorption capacity as well as a good selectivity for Ag(I) in aqueous solution. The enhanced performance is attributed to the specific cavities created in CS matrix by the template Ag(I) ions. The optimal pH value for Ag(I) adsorption was found ~ 5.0 and the adsorbed precious metal can be conveniently recovered by the acid wash.  It is also found that the imprinting ratio can significantly change the adsorption selectivity of the  hydrogels.