Novel polyamidoamine-based hydrogel with an innovative molecular architecture as a Co2+-, Ni2+-, and Cu2+-sorbing material:: Cyclovoltammetry and extended X-ray absorption fine structure studies

An amphoteric polyamidoamine (PAA)-based hydrogel, named INT-PAA1, with a novel molecular architecture was prepared and studied as a Co2+-, Ni2+-, and Cu2+-sorbing material. This hydrogel was obtained by the synthesis of a PAA in the presence of a second presynthesized PAA carrying many primary amino groups as side substituents, which acted as a macromolecular crosslinking agent. Therefore, it had an intersegmented structure. INT-PAA1 exhibited a remarkable sorption capacity and sorption rate for Co2+, Ni2+, and Cu2+ that were advantageously in situ monitored by cyclic voltammetry. An extended X-ray absorption fine structure spectroscopy characterization of the Co2+/INT-PAA1 complex was also performed. The very fast and quantitative metal-ion uptake, made apparent by an intense coloring of the hydrogel, showed remarkable potential for environmental applications such as heavy-metal detection, recovery, and elimination. (c) 2006 Wiley Periodicals, Inc.