Adsorption characteristics of metal complexes by chelated copolymers with amino group

Abstract

Pentaethylenehexamine, a strong-field ligand, was grafted onto copolymer to obtain chelating copolymers via suspension polymerization. The characterization of the chelating copolymers is obtained by using Fourier transform IR spectroscopy (FTIR), elemental analysis (EA), and scanning electron microscopy (SEM), respectively. The N–H group absorption bands at 1560 and 3370–3412 cm −1 are shifted to higher frequency when the cupric ion or Cu(II)–EDTA complex is adsorbed, and an obvious tertiary amine absorption band is observed at 1385 cm −1. The FT-IR spectrum does not exhibit the characterization absorption peak of EDTA. In addition, the results of FTIR, SEM with an energy dispersive spectroscopy (EDS) X-ray spectrometry and ion chromatography analysis reveal that the mechanism by which the metal complex is adsorbed onto the chelating copolymer involves the strong chelating copolymer forcing the release of cupric ion from Cu(II)–EDTA complex to the chelating polymer. The maximum adsorption capacity for cupric ion is 1.25 mmol/g and the adsorption capacity increases with an increase of pH of the solution. The minimum stability constant obtained for the Cu chelating copolymer is 10 18.75, which is larger than that of Cu-EDTA ( K s = 10 18.30), and so the Cu chelating polymer competes with EDTA for the Cu ions. All of the chelating copolymers obtained herein are strong chelating agents and exhibit a chelating ability that allow them to compete with Cu(II)–EDTA complex for cupric ion in waste-water.