Calcium alginate beads reinforced with synthetic oligomers, linear polyethylenimine and Cu(II): structural stability and potential applications

Calcium alginate beads were reinforced with linear polyethylenimine (PEI), Cu(II) and synthetic oligomers derived from a diepoxide, methacrylic acid and imidazole, to increase the resistance to stirring and vibration for environmental applications. The FT-IR and Raman spectra of the beads confirmed the presence of the organic reactants and their interactions. The SEM images of the lyophilized beads with an excess of oligomers exhibited an ordered core structure surrounded by a shell. The elemental mapping by EDAX showed a homogeneous distribution of Ca(II) and Cu(II), and a density influenced by PEI. The beads more resistant to sonication were those with the highest oligomer content. The enzyme soybean peroxidase (SBP) was immobilized in the beads for an environmental application that requires a stable matrix from chemical and structural points of view. The synergistic action of the entrapped SBP and Cu(II) on H2O2 activation induced the removal of an azo dye from aqueous solutions. Free radicals and O-2 were released from Cu(II)-sites in the presence of the peroxide. The content of the oligomers determined the efficiency of the beads on dye removal.