By synthesizing GO-Fe3O4 nanocomposites (graphene oxide coated with magnetite), this study investigated chlorpheniramine (a widely used pharmaceutical) adsorption on magnetic GO-Fe3O4, with respect to the influences of using the nanocomposite suspension or particles, mass ratios of Fe3O4/GO in the synthesis, pH, and contact time. GO-Fe3O4 was characterized by thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, and Brunauer-Emmett-Teller theory. Nano-sized Fe3O4 anchored on GO uniformly, resulting in hybrid structures with well combination between GO and Fe3O4. By fitting to the pseudo 2nd-order model, chlorpheniramine adsorption onto GO-Fe3O4 likely occurred due to a chemical adsorption. The adsorption maximums decreased in the order: GO-Fe3O4 particles > GO-Fe3O4 suspension > activated carbon. With Fe3O4 changing the surface charge of GO-Fe3O4 suspension, pH variation enhanced chlorpheniramine adsorption on. GO-Fe3O4 suspension. The GO-Fe3O4 particles exhibited a relatively better but slow chlorpheniramine adsorption. More importantly, additional nanopore volumes and surface areas were created in GO-Fe3O4 particles due to low Fe3O4 contents to more effectively capture and remove chlorpheniramine, as Fe3O4 crystals on the GO surface potentially prevented the compaction of GO sheets. These factors interactively affected and determined the approach of using GO for removing chlorpheniramine or other pharmaceuticals with similar molecular characteristics in wastewater treatment. (C) 2016 Elsevier B.V. All rights reserved.