Amine-functionalized polyether ether ketone prepared by simple solvothermal method for high-efficiency removal of uranium

Adsorption materials for treating radioactive wastewater must exhibit outstanding adsorption capabilities and robust mechanical, chemical, and radiation stability. In this study, amine-functionalized polyether ether ketone (NPEEK) was synthesized via a Schiff base reaction using a solvothermal method, demonstrating high uranium (U(VI)) adsorption performance. Specifically, NPEEK prepared at 125 °C for 12 h achieved a peak U(VI) adsorption capacity of 220.28 mg/g within 90 min at pH 5, maintaining good adsorption performance after five cycles of experiments. The successful modification of PEEK through ethylenediamine grafting was confirmed by various analyses including Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). The adsorption process aligns well with pseudo-second-order kinetics, Langmuir, intra-particle diffusion, and liquid film diffusion models. It is predominantly governed by chemisorption and monolayer sorption, characterized as a spontaneous endothermic process. Density functional theory (DFT) calculations and molecular dynamics (MD) simulations were employed to elucidate the unique structure and adsorption mechanism from a structural viewpoint. Uranium adsorption occurs via coordination, electrostatic interactions, and intra-particle diffusion. In conclusion, this innovative PEEK-based composite has the potential to address the limitations of existing PEEK-based adsorption materials and emerge as a promising adsorbent for treating uranium(VI)-contaminated wastewater.