Dendrimer Enhanced Ultrafiltration. 1. Recovery of Cu(II) from Aqueous Solutions Using PAMAM Dendrimers with Ethylene Diamine Core and Terminal NH_2 Groups

This article discusses the feasibility of using dendrimer enhanced ultrafiltration (DEUF) to recover Cu(II) from aqueous solutions. Building upon the results of fundamental investigations of Cu(II) binding to PAMAM dendrimers with ethylenediamine (EDA) core and terminal NH_2 groups, we combine (i) dead-end ultrafiltration (UF) experiments with (ii) atomic force microscopy (AFM) characterization of membrane fouling to assess the feasibility of using DEUF to recover Cu(II) from aqueous solutions. On a mass basis, the Cu(II) binding capacities of the EDA core PAMAM dendrimers are much larger and more sensitive to solution pH than those of linear polymers with amine groups. The dendrimer−Cu(II) complexes can be efficiently separated from aqueous solutions by ultrafiltration. The metal ion laden dendrimers can be regenerated by decreasing the solution pH to 4.0; thus enabling the recovery of the bound Cu(II) ions and recycling of the dendrimers. The UF measurements and AFM characterization studies show that EDA core PAMAM dendrimers with terminal NH_2 groups have very low tendency to foul the commercially available regenerated cellulose (RC) membranes evaluated in this study. The overall results of these experiments suggest that DEUF is a promising process for recovering metal ions such as Cu(II) from aqueous solutions