Spectroscopic and theoretical investigation on efficient removal of U(VI) by amine-containing polymers

Amine containing polymers (ACPs) were synthesized by heating glyoxal and melamine under argon conditions. The batch characterization, including SEM, FTIR, XRD and XPS techniques, indicated that ACPs had various nitrogen-containing functional groups. The batch experiments indicated that ACPs presented the high removal performances (Qmax = 250 mg/g, calculated by Langmuir model), well stability, strong salt tolerance and great regeneration cycle toward U(VI). XPS analysis confirmed the coordination of U(VI) with nitrogen- or oxygen-containing groups via covalent bonding. The theoretical calculations revealed that the binding energies of U-N, U-O and U-C were -27.49, -16.94 and -11.81 kcal/mol, respectively, indicating that U(VI) was tended to combine with nitrogen- containing groups. These observations suggested that ACPs can be regarded as a promising adsorbent for immobilization and pre-concentration of U(VI)-containing wastewater in environmental cleanup.