Green synthesis of 3D porous graphene/lignin composites with improved adsorption capacity for heavy metal ions in aqueous solution

摘要

Lignin modified three-dimensional porous graphene (denoted as 3D PG/L) were synthesized via a green hydrothermal and freeze-drying method. The as-prepared 3D PG-L was characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, thermo-gravimetric analysis, X-ray photoelectron spectroscopy and N-2 adsorption-desorption measurements. A series of adsorption experiments for heavy metal ions were used to investigate the effects of lignin on the graphene structure. It was found that 3D PG-L showed a significant increase in oxygen-containing groups and adsorption capacity contrast to 3D PG. These impressive results demonstrated that the as-prepared porous composites achieved the improved adsorption capacity for heavy metal ions from an aqueous solution. The results indicated that the adsorption process matched well with the Langmuir isotherm model and the pseudo-second-order kinetic model. This study provides a novel functional 3D porous graphene as adsorbent for the removal of heavy metal ions from an aqueous solution.