Synthesis and Sorption Characteristics of Magnetic Materials Based on Cobalt Oxides and Their Reduced Forms

Abstract

The study describes direct precipitation, original template, and additional thermal reduction methods for the synthesis of materials based on cobalt oxides and their composites, promising as magnetic sorbents for the selective extraction and preconcentration of uranium(VI) from aqueous media. The thermal decomposition of intermediates and the phase formation of final materials were studied by differential thermal analysis and powder X-ray diffraction. The surface morphology and structure of the obtained sorbent samples were investigated. The sorption activity and capacity of the materials were estimated in relation to the extraction of uranyl ions from aqueous solutions over a broad pH range (2–10), in particular, in the presence of carbonate ions (0.001, 0.01, 0.1, and 1 mg/L). It was found that quantitative sorption of uranium(VI) is dictated, to a higher extent, by the composition of the sorbent solid phase containing metallic cobalt. A set of magnetic measurements were carried out and magnetic characteristics of sorption materials were determined. The saturation magnetization for reduced sorbents can reach 133–237 emu/g, which is an additional benefit for their separation from solutions after treatment by magnetic separation techniques.