Enhanced removal of EDTA-chelated Cu(II) by polymeric anion-exchanger supported nanoscale zero-valent iron

In this study, a polymeric anion exchanger (D201) was utilized as the support for nanoscale zero-valent iron (NZVI), and the resultant nanocomposite (D201-ZVI) was employed to remove EDTA-chelated Cu(II) from water. The removal of EDTA-chelated Cu(II) was significantly enhanced by D201-ZVI in comparison with NZVI over a wide pH range from 5 to 9. Most of the removed Cu (97.2%) was immobilized inside the D201-ZVI beads, implying the enhanced permeation of CuEDTA^2- by the fixated quaternary ammonium groups of the host D201. HPLC analysis revealed that the EDTA-chelated Cu(II) was gradually replaced by Fe(III) originated from Fe⁰ oxidation. Then, the released Cu(II) was in situ removed via adsorption/precipitation, or further reduced into Cu⁰, as quantified by XPS spectra. The higher removal of EDTA-chelated Cu(II) by D201-ZVI than NZVI was mainly ascribed to the enhanced permeation of the host D201 as well as to the better dispersion and higher reactivity of the confined ZVI nanoparticles. Through the combination of periodic regeneration and complete regeneration, D201-ZVI could be sustainably employed for EDTA-chelated Cu(II) removal. Also, D201-ZVI exhibited great potential for practical application in the fixed-bed column operation. Therefore, the D201-ZVI nanocomposite was promising in highly efficient removal of EDTA-chelated Cu(II) from water.