Magnetic nanoparticles/graphitic carbon nanostructures composites: Excellent magnetic separable adsorbents for precious metals from aqueous solutions

A facile, low-cost and high-yield route was used for synthesis of magnetic nanoparticles/graphitic carbon nanostructures (MNPs/GCNs) adsorbents with adjustable GCNs structues, in which the cheap ion-exchanged resins and iron salts were adopted as the precursors. The synthesized MNPs/GCNs composites could be used as effective mobile adsorbents for removal of precious metal ions (Ag+ and Au3+). The adsorption quantity of the adsorbents for Ag+ and Au3+ ions is up to 7.88 mg/g and 7.92 mg/g, respectively, which is much higher than that of activated carbon. Notably, the adsorbents could be easily separated from solution with a commercial magnet due to the magnetic property, which is very beneficial to their practical application. The kinetics for Ag+ and Au3+ ions adsorption on MNPs/GCNs composites followed the pseudo-second-order kinetics. The XPS analyses demonstrated that the adsorbed Ag+ and Au3+ ions exsited in the form of the zero valence state silver and gold, respectively.

Graphical abstractThe magnetic nanoparticles/graphitic carbon nanostructures (MNPs/GCNs) composites synthesized via solid-state pyrolysis could be used as effective mobile adsorbents for removal of precious metal ions (Ag+ and Au3+).Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The MNPs/GCNs adsorbents with tuned microstructure of GCNs were successfully fabricated by a simple solid-state pyrolysis route. ► The MNPs/GCNs composites had shown excellent adsorption performance for Ag+ and Au3+. ► The largest absorbed percentage for Ag+ and Au3+ is up to 99%. ► The MNPs/GCNs adsorbents could be easily separated by a commercial magnet. ► The adsorption kinetics for precious ions of Ag+ and Au3+ followed the pseudo-second-order kinetics.