Metal adsorption properties of multi-functional PAMAM dendrimer based gels

Metal adsorption studies are getting important and there are many functional adsorbents developed recently. Here, we report the synthesis of multifunctional PAMAM G2 (polyamidoamine) possessing methacryl, amine, hydroxyl and phosphonate groups used in free radical curing gel formulations. UV curable gel is conducted in the presence of acrylamide, bisacrylamide, and polyethylene glycol diacrylate. Adsorption study of the resulting novel sorbents (gels) are carried out with a series of metals. Through a comprehensive study, structure–property relationship of the series gels is conducted by using different amount of amine, hydroxyl, and/or phosphonate ester groups on the PAMAM G2. Selected metals are Cr³⁺, Fe³⁺, Ni²⁺, Cu²⁺, Ag⁺, and Cd²⁺ within a series of hard, intermediate, and soft ionic species. Adsorption study is carried out in pure water environment at neutral pH. Metal ions removal percentages and adsorption capacities of gel adsorbents are calculated by using atomic absorption spectroscopy. There is relationship between the overall functional groups presence in gel formulation and swelling densities for removing the metal ions. Introducing dendrimer into the gel formulation enhanced the metal ions adsorption against to Bare GEL formulation which do not possess dendrimer units. Consequently, the maximum removal efficiency has been obtained for Cr³⁺ and Fe³⁺.