Preparation and metal-binding behaviour of chitosan functionalized by ester- and amino-terminated hyperbranched polyamidoamine polymers

A series of insoluble chitosan (CTS) derivatives were prepared by grafting ester- and amino-terminated dendrimer-like polyamidoamine (PAMAM) into CTS using a divergent method by repeating two processes: (1) Michael addition of methyl acrylate (MA) to surface amino groups, and (2) amidation of the resulting esters with ethylenediamine (EDA). Their structures were characterized by infrared spectra (IR) and wide-angle X-ray diffraction (WAXD). The adsorption capabilities of the products for Au3+, Pd2+, Pt4+, Ag+, Cue(+), Zn2+ Hg2+, Ni+, and Cd2+ were studied. The results showed that the products exhibited better adsorption capabilities for Au3+ and Hg2+ than for other metal ions, and the adsorption capabilities of amino-terminated products were higher than those of ester-terminated ones. Also it was observed that a high percentage of grafting of PAMAM into CTS does not ensure a high adsorption capacity. (c) 2007 Elsevier Ltd. All rights reserved.