SYNTHESIS AND CHARACTERIZATION OF AMIDE LINKAGE-INCORPORATED POLYETHYLENEIMINE-BASED CHELATING RESINS AND STUDIES OF THE CROSS-LINK DENSITYAND SURFACE-PROPERTIES ON METAL-ION UPTAKE

The chelating resins incorporating amide linkages were synthesized in open reaction vessels (OV) by polycondensing different proportions, vi z., 1 : 1, 1 : 1.3, and 1.3 : 1 of polyethyleneimine (PEI) and diethyl enetriaminepentaacetic acid (DTPA), respectively, at 145-155 degrees C , and at varying curing times (15 h and 22 h). For the proportion 1 : 1, the synthesis was performed in a closed reaction vessel (CV) as wel l. The resins were characterized by FTIR, elemental, and thermogravime tric analysis, apart from sarptometric surface studies. The extent of crosslinking was evaluated by swelling measurements and the chemical s tability was assessed by acid and alkali treatment. The effect of the mode of heating and curing times on the extent of crosslinking and por e structure modifications were evaluated. The influence of these facto rs on the capacities, the kinetics, and the break through curve trends of these resins were studied using zinc and cadmium metal ions as ref erences. The reproducibility of the resins were ascertained by assessi ng the extent of change in the break through curve trends of their dif ferent batches, synthesized under identical conditions. (C) 1993 John Wiley & Sons, Inc.