Application of graphitic carbon nitride for the removal of Pb(II) and aniline from aqueous solutions

• g-C3N4 was synthesized by a facile one-step approach.
• g-C3N4 can effectively remove Pb(II) and aniline from aqueous solutions.
• g-C3N4 owns a very good chemical stability and reusability in the removal of heavy metal ions and organic molecules.

Graphitic carbon nitride (g-C3N4) was synthesized from urea with a facile approach and was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transformed infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The as-synthesized g-C3N4 was applied as sorbent to remove Pb(II) and aniline from aqueous solutions as a function of contact time, solid content, pH, ionic strength, temperature, and initial concentrations of Pb(II) and aniline. The results indicated that the sorption of Pb(II) was mainly dominated by outer-sphere surface complexation or ion exchange at pH < 7.0, but by inner-sphere surface complexation at pH > 7.0. The sorption of aniline was mainly attributed to electrostatic interaction at pH < 5.0, whereas the π–π electron donor–acceptor (EDA) interaction was the predominant sorption mechanism at pH > 5.0. The sorption isotherms of Pb(II) and aniline on g-C3N4 were well described by the Langmuir model. The thermodynamic parameters calculated from the temperature-dependent sorption isotherms indicated that the sorption of Pb(II) and aniline on g-C3N4 was endothermic and spontaneous processes. Moreover, g-C3N4 could be regenerated through the desorption of Pb(II) and aniline by using 1.0 M HCl solution and alcohol, respectively, and no obvious decline of sorption capacity was found for the recycling results. All these results indicated that g-C3N4 was a promising material for the preconcentration of Pb(II) and aniline from aqueous solutions in real pollution management.