Hybrid ion exchangers containing Fe(III)-Cu(II) binary oxides obtained using macroreticular anion exchanger

Abstract

Considering the performance of parent Fe(III)-Cu(II) binary oxide nanoparticles in removing numerous contaminants from water, in order to prevent the release of the nanostructures into the cleaned water a deposit with the same composition was introduced into the matrix of a synthetic porous material (ion exchange resin), whereby a hybrid ion exchanger (HIX) was obtained. Amberlite 900 Cl, a commercially available strongly basic macroreticular anion exchanger, was used as the supporting material. The inorganic deposit was introduced into its structure in two steps performed batchwise at ambient temperature. Fe(III)-Cu(II) binary oxide could be deposited into the matrix of the strongly basic anion exchanger owing to the affinity of its functional groups for FeCl4− and CuCl42− ions. When in the ion exchange reaction the anion exchanger bound both the ions and the reaction medium alkalized, the respective oxides FeOOH and CuO precipitated in its structure. The oxide deposit was introduced into the ion exchanger in three ways, whereby HIXs differing in their oxide content, in the mole ratio of the oxides and in the latter's atypical distribution in the matrix of the anion exchanger were obtained. Regardless of the method of conducting the reaction, HIXs rich in oxides, e.g. 3.73 mmol (Fe, Cu) g−1 (2.35 mmol Fe and 1.38 mmol Cu g−1 at Fe/Cu = 1.7) were obtained. The products were investigated by SEM, EDXS, T/TG/DTA, XRD and VSM. The doped HIXs are characterized by a core-shell structure, where the core consists of polymeric beads and the outer thin layer contains Fe and Cu in their oxidized form. The structure of the outer layer varies depending on the procedure of precipitation. These differences are also reflected in the magnetic properties (ferromagnetic or paramagnetic interaction). CuFe2O4 was found to be present in the samples sintered at 900 and 1300°C, which proves that a ferrite can form from the deposit after a solid-state reaction at high temperatures.