Fabrication of a magnetic porous hydrogel sphere for efficient enrichment of Rb+ and Cs+ from aqueous solution

Abstract

A series of magnetic porous hydrogel spheres were prepared from the oil in water (O/W) Pickering emulsion stabilized with silicone-modified magnetic attapulgite (MAPT), using hydroxypropyl cellulose (HPC) as the grafting backbone and acrylic acid (AA) as the monomer. The structure, morphologies and physico-chemical features of the Pickering emulsions and the hydrogel spheres were characterized by TEM, SEM, XRD and TGA techniques. The results revealed that the Fe3O4 was attached on the surface of APT with good dispersion, and the magnetic APT (MAPT) was modified successfully with silane. The emulsion with HPC, AA, initiator and crosslinker inside can be directly dropped into hot liquid paraffin to form hydrogel sphere. The rod-like APT as the stabilizer facilitated to form open pore and interconnected pores. The magnetic porous hydrogel sphere can rapidly adsorb the rare elements Rb+ and Cs+, with the maximum adsorption capacities of 232.46 and 239.88mg/g, respectively. The adsorbed Rb+ and Cs+ ions can be recovered by a simple desorption process, and the hydrogel sphere also showed excellent reusability after five consecutive adsorption–desorption cycles. This porous sphere with excellent adsorption capability and rate is potential adsorbent for the adsorption and enrichment of rare metals Rb+ and Cs+.