Preparation of efficient heavy metal adsorbent based on walnut shell and adsorption for Pb(II) ions from aqueous solution

An efficient heavy metal absorbent, amino-terminated hyperbranched polymer modified walnut shell (FWNS) was prepared. The adsorption behavior for Pb(II) ions from aqueous solution was also discussed. The FWNS was prepared using an amino-terminated hyperbranched polymer (ATHBP) as modifying agent and glycidyl methacrylate(GMA) as the grafting bridge. The FWNS was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Scanning electron microscope (SEM). The adsorption capacity of FWNS for Pb(II) was investigated at different adsorbent dosages (0.25–2.5gL −1 ) and pH (from 2.0 to 6.0). The result indicated that the absorbent had good adsorption capacity over a wide pH range (2.0–6.0). The maximum Pb(II) ions adsorption capacity (Q m ) obtained by a Langmuir fitting model was 1250.00 mg/g at 293 K. The adsorption kinetics fitted the pseudo-second-order equation. The adsorption of FWNS for Pb(II) ions was an endothermic reaction and spontaneous process. Furthermore, the result shows FWNS has excellent regeneration.