Superparamagnetic polyvinylpyrrolidone/chitosan/Fe3O4 electrospun nanofibers as effective U(VI) adsorbents

Magnetoactive electrospun fibrous membranes consisting of polyvinylpyrrolidone (PVP), chitosan (CS) and pre-fabricated, double-layer oleic acid-coated magnetite nanoparticles (OA.OA.Fe3O4) were fabricated and evaluated as new adsorbent materials for the removal and recovery of uranium (U(VI)) from aqueous solutions. The adsorption has been investigated by batch-type experiments and the solid material has been characterized by X-ray diffraction spectroscopy (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy/energy dispersive X-ray analysis (TEM/EDX) and vibration sample magnetometry (VSM) measurements prior and after uranium adsorption. The experimental adsorption data were found to be well fitted with the Langmuir isotherm and the pseudo-second order kinetic model. The results indicate that PVP/CS/OA.OA.Fe3O4 fibrous adsorbents exhibit good adsorption properties towards U(VI) in aqueous solutions, achieving a q(max) value of 0.77 mol kg(-1) (183.3 mg g(-1)) at pH 6.0. The experiments regarding the regeneration and reuse of the magnetoactive adsorbents were carried out using Na2CO3, at pH similar to 11. After four cycles, the percentage relative adsorption remained stable (similar to 100%) whereas the desorption percentage decreased from 31.9% to 21.0%. Generally, the presented results demonstrate that the incorporation of the Fe3O4 NPs has a positive effect on the adsorption efficiency of U(VI) from aquatic environments.

Automated summary

Magnetoactive electrospun fibrous membranes composed of PVP, CS, and pre-fabricated OA.OA.Fe3O4 nanoparticles were successfully used for the removal of uranium from aqueous solutions. The inclusion of Fe3O4 NPs was found to enhance the adsorption efficiency of U(VI) from aquatic environments, with stable relative adsorption percentages and decreased desorption percentages observed after regeneration and reuse experiments.