Synthesis of multi-walled carbon nanotube-hydroxyapatite composites and its application in the sorption of Co(II) from aqueous solutions

► MWCNT-HAP composites were synthesized and used to remove Co(II). ► Foreign ions affected Co(II) sorption on MWCNT-HAP composites. ► Co(II) sorption on MWCNT-HAP composites is a spontaneous and endothermic process. ► MWCNT-HAP composites can be used to remove heavy metal ions in large scale.