Core–shell magnetic chitosan particles functionalized by grafting: Synthesis and characterization

A method for preparing magnetic composite particles with a core containing iron oxide encapsulated in crosslinked chitosan (CS) and a functionalized synthetic copolymer shell is proposed and optimized. The magnetic material is produced in situ. Surface vinyl groups are introduced by attaching glycidyl methacrylate (GMA) to the hydroxyl or amino chitosan residues via ether or N-alkyl bonds in acidic medium. These groups are used in a subsequent synthesis step as starting points for free radical copolymerization of GMA, ethylene glycol dimethacrylate (EGDMA) and poly(ethylene glycol methylmethacrylate) (PEG-MMA). The epoxy rings are opened in the final step with ethylenediamine (EDA). The results confirm that a grafted polymer layer has been anchored on the surface by covalent bonds. Sorption batch experiments using copper (II) ion solutions were conducted in order to compare the performance of the synthesized materials as heavy metal adsorbents. The functionalized particles show superior adsorption capacity compared to the ungrafted material.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Particles with magnetic chitosan core and synthetic copolymer shell are prepared. ► Synthesis study targeted stable particles and high metal ion adsorption capacity. ► Analyses confirm that core particles are successfully covered with polymeric layer. ► Superior Cu(II) adsorption capacity compared to ungrafted material is demonstrated. ► Possible applications in heavy metal ion separation from wastewater is suggested.