Preparation of magnetic polyethylenimine lignin and its adsorption of Pb(II).

In this paper, magnetic polyethyleneimine lignin (M-Lignin-PEI) was prepared by a reversed-phase suspension crosslinking method to remove Pb (II) form aqueous solutions. SEM, FT-IR, TGA, XRD and VSM technology were employed to explain their structures. Batch adsorption experiments for Pb (II) were carried out to estimate their adsorption performance. Results showed that lignin successfully grafted with polyethyleneimine and coated on the surface of Fe3O4 with a saturation magnetization of 24.08 emu/g, which could achieve good solid-liquid separation. In addition, the experiment results indicated that the adsorption of Pb (II) by M-Lignin-PEI was in line with Langmuir model, and the adsorption process could be described by a pseudo-second-order model, suggesting that Pb (II) adsorption onto sorbents were a chemical process and monolayer adsorption. The maximum adsorption capacity of M-Lignin-PEI for Pb (II) could reach 96.60 mg/g and the removal rate was 99.73%. Moreover，the lead-loading M-Lignin-PEI could be easily regenerated with only 15% decrease of adsorption capacity after five times regeneration.