PEI-grafted magnetic porous powder for highly effective adsorption of heavy metal ions

The aim of this study is to develop a polyethylenimine (PEI) grafted magnetic porous adsorbent for highly effective adsorption of heavy metals. The process of grafting PEI was confirmed by Fourier transform infrared (FTIR) analysis. Batch tests were carried out to investigate the adsorption performance. Adsorption of Cu2+, Zn2+ and Cd2+ was dependent on pH and increasing the pH was favorable to metal ions removal. The adsorption equilibrium was reached within 10 min and well described by pseudo-second-order model. The sorption isotherms of the adsorbent for these metals fitted well with Langmuir model, with maximum adsorption capacities of 157.8, 138.8 and 105.2 mg/g for Cu2+, Zn2+ and Cd2+, respectively. Competitive adsorption among the three metal ions showed a preferential adsorption of Cu2+ > Zn2+ > Cd2+. The magnetic adsorbent exhibited excellent acid–alkali stability. In addition, the exhausted adsorbent can be regenerated by 0.02 mol/L EDTA solution without significant adsorption capacity loss.