Nanosized amine-rich spheres embedded polymeric beads for Cr (VI) removal.

Porous matrix immobilization is considered as an effective approach to address the engineering challenges during practical application of nanoadsorbent. In this work, polyethersulfone (PES) beads with diameter of around 2.5mm, in which nanosized amine-rich polymer spheres (APSs) with particle size of ∼400nm are immobilized, are fabricated via phase inversion route. APSs-PES beads possess asymmetric and hierarchical structure with an exterior porous surface dense layer and numerous inner interpenetrating fingerlike channels, which promote the transportation of molecule and prevent the leaching of nanoadsorbents. The well distributed APSs with nitrogen-containing functional groups provide abundant adsorption sites. The cooperative attributing of the hierarchical structure and APSs demmonstrates enhanced Cr (VI) adsorption efficiency. The adsorption capacity of Cr (VI) is 243.9mg/g at 298K by Langmuir fitting. The effects of pH, temperature, the ratio of adsorbents and coexisting ionic are further studied in detail. The Cr (VI) removal mechanism is further explored by the combination of SEM, XPS, FTIR measurements and the adsorption parameters, further revealing the synergistic contribution of electrostatic attraction and reduction process. Therefore, this kind of adsorbents may show promising prospects on elimination of hazardous Cr (VI) in wastewater treatment.