Adsorption properties of polyethyleneimine modified magnetic yeast composites for uranium (VI)

In order to efficiently and conveniently treat radioactive wastewater, polyethyleneimine (PEI) modified magnetic yeast(MY) composite biological material(MY@SiO₂-PEI) was prepared and used for the removal of uranium (VI).The material was characterized by SEM, FTIR, Zeta potential and XPS, the U(VI) morphology distribution under different conditions was simulated by Visual MINTEQ, the different solution pH, temperature, reaction time, ionic strength, anion interference(CO₃²⁻, PO₄³⁻) and different U(VI) in terms of initial mass solubility were analyzed. In addition, the influence of different factors on the adsorption performance of MY@SiO₂-PEI on U(VI) was investigated, and the recycling capacity of MY@SiO₂-PEI was studied. The results show that the adsorption of U(VI) by MY@SiO₂-PEI shows a strong pH dependence, and the ionic strength does not significantly interfere with the adsorption effect, indicating that the reaction is mainly controlled by surface complexation. FTIR, XPS and Zeta potential analysis found that the main factor that promotes the adsorption of U(VI) is the complexation and electrostatic attraction of different functional groups (N=C, NH(NH₂), C—N=C) and U(VI) on the surface of the material. The maximum adsorption capacity of MY@SiO₂-PEI can reach 173.99 mg/g, and the adsorption equilibrium can be reached within 20 minutes. Quasi-second-order kinetics and Langmuir isotherm equation can fit this adsorption process well, and thermodynamics show that the adsorption process is a spontaneous endothermic process. MY@SiO₂-PEI material has simple synthesis method, good removal effect and good reproducibility. It is a promising adsorbent for radionuclides in environmental pollution control.