Removal of cobalt ions from aqueous solution by an amination graphene oxide nanocomposite

•A newly designed GO-NH2: Higher adsorption capability than that of activated carbon.•Very quick adsorption property: More than 90% of Co(II) can be removed within 5min.•One of the highest adsorption capabilities of today's nanomaterials for Co(II) (116.35mg/g).•GO-NH2 membrane can remove more than 98% Co(II) from the water. A newly designed amination graphene oxide (GO-NH2), a superior adsorption capability to that of activated carbon, was fabricated by graphene oxide (GO) combining with aromatic diazonium salt. The resultant GO-NH2 maintained a high surface area of 320m2/g. When used as an adsorbent, the GO-NH2 demonstrated a very quick adsorption property for the removal of Co(II) ions, more than 90% of Co(II) ions could be removed within 5min for dilute solutions at 0.3g/L adsorbent dose. The adsorption capability approaches 116.35mg/g, which is one of the highest capabilities of today's materials. The thermodynamic parameters calculated from temperature-dependent adsorption isotherms suggested that the Co(II) ions adsorption on GO-NH2 was a spontaneous process. Considering the superior adsorption capability, the GO-NH2 filter membrane was fabricated for the removal of Co(II) ions. Membrane filtration experiments revealed that the removal capabilities of the materials for cobalt ions depended on the membrane's thickness, flow rate and initial concentration of Co(II) ions. The highest percentage removal of Co(II) exceeds 98%, indicating that the GO-NH2 is one of the very suitable membrane materials in environmental pollution management.