Amine-terminated dendritic polymers as a multifunctional chelating agent for heavy metal ion removals

In this study, amine-terminated hyperbranched PAMAM (polyamidoamine) polymer (AT-HBP) was synthesized as a multifunctional chelating agent to remove two heavy metal ions (Cr(III) and Cu(II)) from the simulated wastewater solutions. The AT-HBP was characterized by Fourier transformed infrared (FTIR), dynamic light scattering (DLS), and proton nuclear magnetic resonance (¹H NMR) analysis. The removal process was carried out in two different methods, centrifuged process and ultrafiltration. The concentration of heavy metal ions before and after removal was measured by inductively coupled plasma (ICP) instrument. The removal processes were evaluated by changing different parameters such as solution pH, AT-HBP dosage, and metal ion concentration. To evaluate the extend of binding of heavy metal ions in the presence of AT-HBP the presence of salt in the solution was also examined on the performance of the removal system. The overall results indicated that removal percentages higher than 98% for Cr(III) and 86% for Cu(II) were achieved for heavy metal concentrations of 100 mg/L for both removal process methods. Furthermore, the function of second generation of polypropylenimine (PPI) was compared to AT-HBP. The results reveal that the removal of Cr(III) and Cu(II) ions by AT-HBP were approximately 20% and 10% higher compared to PPI, respectively. Finally, hyperbranched dendritic polymer with lower expenses to synthesize compared to dendrimer underlined favorable properties as a multifunctional chelating agent and enhancement of ultrafiltration process for wastewater treatment. Graphical abstract.