High performance of 3D porous graphene/lignin/sodium alginate composite for adsorption of Cd(II) and Pb(II)

A novel adsorbent, three-dimensional porous graphene/lignin/sodium alginate nanocomposite (denoted as 3D PG/L/SA) was fabricated by hydrothermal polymerization of lignin and sodium alginate in the presence of graphene oxide (GO) in an aqueous system. Fourier transform infrared spectra, thermo-gravimetric analysis, scanning electron microscopy, and X-ray photoelectron spectroscopy were employed to characterize the morphology and structure of this novel functional PG/L/SA nanocomposite. A series of adsorption experiments for cleanup of Cd(II) and Pb(II) were conducted to investigate the effects of lignin and sodium alginate on the graphene structure. It was found that PG/L/SA showed a significant increase in adsorption capacity contrast to porous graphene (PG). The as-prepared material achieved the adsorption capacity for Cd(II) and Pb(II) of 79.88 and 226.24 mg/g, respectively. Meanwhile, the adsorption process matched well with the Langmuir isotherm model and the pseudo-second-order kinetic model. Studies were also conducted to demonstrate the applicability of the sorbent to the removal of heavy metal ions from metal smelting wastewater.