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.

Automated summary

The adsorption behavior of amino-terminated hyperbranched polymer modified walnut shell (FWNS) towards Pb(II) ions in aqueous solution was investigated. The results showed that FWNS had excellent adsorption capacity over a wide pH range, making it an efficient absorbent for heavy metals.