Synthesis, Characterization, and Catalytic Properties of Cationic Hydrogels Containing Copper(II) and Cobalt(II) Ions

Abstract

Here, we report the synthesis and characterization of a hydrogel based on ethylene glicol diglycidyl ether (EGDE) and 1,8-diamino-3,6-dioxaoctane (DA). Chemically stable Co(II) and Cu(II) coordination complexes were prepared with this non-soluble polyelectrolyte, Poly(EGDE-DA), and studied by ss-NMR, FTIR, thermogravimetry and microscopy. Mesopores were found in all the samples, the thermal stability of the polymer matrix was highly affected by the presence of metal ions, and the 13C CP-MAS spectrum for the Cu(II)-complex evidenced a significant increase in the reticulation degree by Cu(II) ions. The catalytic activity of these materials on H2O2 activation was studied by Electron Spin Resonance (ESR). The Co(II)-Poly(EGDE-DA) / H2O2 heterogeneous system produced O2, anion superoxide (O2*¯) and hydroxyl radical (OH*), which diffused into the solution at the time that a decrease in pH was detected. In the same way, the Cu(II)-Poly(EGDE-DA) / H2O2 heterogeneous system produced O2 and OH*. H2O2 activation by the Poly(EGDE-DA) complexes with Co(II) and Cu(II) was applied on the decolorization of solutions of the azo-dye Methyl Orange (MO). In the presence of 63 mM H2O2, 87 % of MO was removed in 10 min with Cu(II)-Poly(EGDE-DA) and in 110 min with Co(II)-Poly(EGDE-DA). In addition, the pharmaceutical product epinephrine was partially oxidized to adrenochrome by the O2*¯ released from the Co(II)-Poly(EGDE-DA) / H2O2 heterogeneous system.