Preparation of zirconium–manganese oxide/polyacrylonitrile (Zr–Mn oxide/PAN) composite spheres and the investigation of Sr(II) sorption by experimental design

Zirconium–manganese oxide/polyacrylonitrile (Zr–Mn oxide/PAN) composite spheres were prepared to remove strontium ions from aqueous solution. Zr–Mn mixed hydrous oxide powder was synthesized via co-precipitation and then mixed with polyacrylonitrile (PAN) as a binding material to form a Zr–Mn oxide/PAN composite spheres. The surface of the composite spheres was modified with 1 M NaOH. The effect of pH, temperature, initial strontium concentration and shaking time on strontium sorption were investigated via experimental design method using central composite design (CCD). Central composite design, with seven replicates at the centre points and thus a total of 31 experiments were employed in this study. A second-order polynomial equation related to the model was obtained and 3 dimensioned surface contour plots were drawn. The characterization of the adsorbent was performed by XRD, SEM, surface area and porosity analysis. Chemical stability of the composite spheres was tested against acidic media. Sorption data have been interpreted in terms of Freundlich, Langmuir and Dubinin–Radushkevich isotherms. Thermodynamic parameters for the sorption system have been determined.