Environmental separation and enrichment of gold and palladium ions by amino-modified three-dimensional graphene

The excellent adsorption properties of three-dimensional graphene (3DG) can be further enhanced by triethylenetetramine modification to increase its adsorption capacity for precious metal ions. Herein, we successfully synthesized an amino-modified 3DG (N-3DG) adsorbent with improved adsorption conditions with regards to pH value, dosage, and adsorption time. Adsorption equilibrium was reached at pH 3 over 120 min. In addition, the theoretical basis for the adsorption of N-3DG is provided by fitting the adsorption isotherm model. The synthesized material was tested in seawater and lake water samples for the adsorption of precious metals, namely Au(III) and Pd(II), achieving a recovery rate of 87% to 106% as assessed by inductively coupled plasma mass spectrometry. Thus, N-3DG showed good adsorptivity. The present results indicate that N-3DG materials could have a viable application in environmental and sewage treatment in the near future.