Graphene oxide/polypyrrole composites for highly selective enrichment of U(VI) from aqueous solutions

Graphene oxide/polypyrrole (GO/PPy) composites were synthesized via a dielectric barrier discharge (DBD) plasma technique in nitrogen conditions, and characterized by scanning electron microscopy (SEM), Raman spectroscopy, thermal gravimetric analysis (TGA), Fourier transformed infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The sorption of U(VI) ions on GO/PPy composites from aqueous solutions was investigated as a function of contact time, pH, ionic strength and U(VI) initial concentrations. The sorption capacity of U(VI) on GO/PPy composites was much higher than those of U(VI) on GO, PPy and many other materials of today. The sorption of U(VI) on GO/PPy composites obeyed the Langmuir model, and was mainly attributed to surface complexation via the coordination of U(VI) ions with oxygen-and nitrogen-containing functional groups. The selectivity sorption of U(VI) ions on GO/PPy composites in the presence of other metal ions (i.e., Co(II), Ni(II), Cd(II), Sr(II), Zn(II)) indicated an overall preference for U(VI) ions. Moreover, the GO/PPy composites could be regenerated through the desorption of adsorbed U(VI) ions by using 1.0 M HCl solution, and cycling reused without an obvious decrease of sorption capacity. All these performances indicate that GO/PPy composites are suitable materials for the highly selective removal and preconcentration of U(VI) ions from aqueous solutions in environmental pollution management.