Hierarchically structured microgels of SPIONs, nanofibers, and alginate for copper ion removal

Abstract

Microgels have been developed for various practical applications such as heavy metal removal. However, their internal structures are difficult to control for a specific application. This study, for the first time, confirms that a hierarchical structure improves the ability of microgels in heavy metal ion removal. Superparamagnetic iron oxide nanoparticles (SPIONs) were incorporated into polylactic acid nanofibers which were then incorporated into alginate microgels, both of which have metal removal capability. A combination of electrospinning and spraying was used to prepare the microgels. The fibers outside the microgels were selectively dissolved out in a subsequent step. The fiber density inside the microgels could be controlled by the electrospinning time. This SPION-loaded nanofiber-entrapped alginate microgel showed outstanding Cu2+ ion adsorption compared to ones without SPIONs or nanofibers. This hierarchical microarchitecture of microgel could find various applications in the fields of future environmental applications.