Synthesis and properties of porous δ-MnO2/polymer millimeter-sized beads for Ni(II) removal

Abstract

In order to overcome the difficulties in separating the powdered adsorbent from the aqueous solution, a novel δ-MnO 2 /polymer millimeter-sized bead adsorbent (MPBs) was synthesized by phase-inversion method. The structure and surface characteristics of the obtained adsorbents were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), N 2 adsorption-desorption (N 2 -AD), Fourier transform infrared spectrum (FT-IR) and energy dispersive x-ray spectroscopy (EDX). Results showed that the MPBs adsorbent had a smooth surface and a porous internal structure, and the manganese dioxide maintained δ-type polymorphic forms. The millimeter-sized bead made the adsorbent ease of application and facile to regeneration in removal of heavy metal ions from aqueous solution. The adsorption properties of MPBs for Ni(II) ions were investigated on the basis of contact time, initial ions concentration and pH value of the solution. The Langmuir isotherm model and the pseudo-second-order kinetic model were applied to fit the adsorption data, and the maximum adsorption capacity of 31.71 mg g −1 for Ni(II) could be inferred. The ions-loaded MPBs could be separated readily from aqueous solution with little of filter resistance and regenerated easily by acid elution. • A novel δ-MnO 2 /polymer millimeter-sized bead was synthesized by phase-inversion. • As-prepared MPBs has a smooth surface and a porous internal structure. • The MPBs is suitable for treating the weak acidic wastewater containing Ni(II). • The millimeter-sized beads make them ease of separation from aqueous solution. • The adsorption capacity of MPBs is stable with multiple usage cycles.