New chitosan modified with epichlohydrin and bidentate Schiff base applied to removal of Pb2+ and Cd2+ ions

In this study, modified chitosan with epichlohydrin and bidentate Schiff base ligand (CEP) was successfully synthesized and characterized using Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), X-ray powderdiffraction (XRD), and scanning electron microscopy (SEM). In addition, its removal ability of Pb2+ and Cd2+ ions was studied and the effect of various parameters such as pH solution, sorbent dose, and contact time on the adsorption of Pb2+ and Cd2+ ions were investigated and optimized. At optimal conditions (pH of 5, contact time of 90 min, 40 ppm of Pb2+, Cd2+ concentration, and 0.02 g of CEP), the maximum removal percentage of Pb2+ and Cd2+ ions was found to be 95 and 79%, respectively. The adsorption process followed the second-order kinetic model for Pb(II) and the first-order kinetic model for Cd(II). In addition, the effect of interface ions was investigated and it was found that the presence of divalent cations only affected the adsorption of Pb(II) and Cd(II) using CEP. Finally, the CEP adsorbent has undergone five regeneration experiments and adsorption efficiency was reduced by about 9 and 12% for Pb(II) and Cd(II) ions, respectively. Results show that the CEP has great potential for the removal of other heavy metal ions as a facile, eco-friendly, and low-cost adsorbent.