Preparation Of PEI Modified Chitosan Magnetic Hydrogel And Its Heavy Metal Adsorption Kinetics

The harm of heavy metal water pollution is very great,and it is relatively difficult to treat it,and it may even cause certain harm to the human body,which is a major concerned problem in today’s environmental protection.In this project,PEI modified chitosan magnetic hydrogels were prepared successfully by grafting polyethyleneimine（PEI）onto chitosan that the natural macromolecular chitosan（CS）was used as the carrier,glutaraldehyde as the cross-linking agent,and magnetic Fe₃O₄ nanoparticles are synthesized by co-precipitation method,And using scanning electron microscopy（SEM）,infrared spectroscopy（FT-IR）,X-ray photoelectron spectroscopy（XPS）,thermal stability analysis（TGA）,comprehensive physical property testing（PPMS）and other structural and physical characterizations,while exploring the structural characteristics and Its adsorption kinetics for heavy metal ions,isotherm adsorption model,adsorption thermodynamics research.The experimental results show:1.PEI modified chitosan magnetic hydrogel has good swelling properties.The higher the molecular weight and the dosage of PEI,the higher the swelling rate.High temperature and acidic and alkaline conditions are not conducive to its swelling.The PEI modified chitosan magnetic hydrogel reached swelling equilibrium at 20℃and p H 7,and its saturated swelling rate was 30.8g·g^-1.2.After PEI modification,the adsorption capacity of heavy metals in the chitosan magnetic hydrogel was significantly increased.The larger the molecular weight of PEI and the greater the amount of PEI,the greater the adsorption capacity of PEI modified chitosan magnetic hydrogel to heavy metal ions.The saturated adsorption capacity for Cu²⁺is 136.89mg·g^-1,for Ni²⁺is 110.32 mg·g^-1,and for Pb²⁺is 85.42 mg·g^-1.3.In a certain range,the greater the p H value,the higher the temperature,the greater the initial concentration,and the lower the concentration of interfering ions,the greater the adsorption capacity of PEI modified chitosan magnetic hydrogels to the heavy metal ions.The adsorption equilibrium was reached in 2 hours.The two-component and three-component competitive adsorption results show that the competitive ability of hydrogels for heavy metal ions is Cu²⁺>Ni²⁺>Pb²⁺.4.The adsorption mechanism of PEI modified chitosan magnetic hydrogel shows that the adsorption of heavy metal ions by the hydrogel is mainly the coordination and complexation of-CO-NH-,-OH and-NH₂,and the adsorption process is spontaneous and It is an endothermic reaction;the adsorption kinetics is more in line with the quasi-second-order kinetic model;the adsorption process is the Langmuir isotherm adsorption model.