Adsorption of pharmaceuticals on chitosan-based magnetic composite particles with core-brush topology

•Chitosan-based magnetic composite particles with core-brush topology are synthesized.•These particles have improved surface areas resulting from core-brush topology.•These particles have high adsorption efficiency in the removal of diclofenac sodium.•CD-MCP with polycationic brushes displays the highest adsorption capacities.•Charge attraction was the intrinsic driving force promoting adsorption.