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

Abstract

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 qmax 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 ~11. After four cycles, the percentage relative adsorption remained stable (~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.

Ofloxacin Removal from Aqueous Media by Means of Magnetoactive Electrospun Fibrous Adsorbents

“…This result is in line with our group’s previous studies dealing with magnetically functionalized electrospun fibrous membranes that were evaluated as adsorbents for the removal of U(VI) and Eu(III) from aqueous solutions, [ 28 , 29 ] thus highlighting the significance of magnetic functionalization in the development of effective adsorbents destined for use in water-remediation processes.…”

“…More precisely, a 13% and 9% OFL removal was observed in the case of the pristine fibrous membrane at pH 4 and 6, respectively, whereas the percentage removal was increased to 39% and 21% when the magnetically functionalized fibrous adsorbent was used instead. The same positive effect of magnetic nanoparticle functionalization on the adsorption efficacy of previously reported electrospun fibrous membranes employed as substrates for the removal of various contaminants, including antibiotics from aqueous media, was also observed [ 28 , 29 , 60 ]. Exemplarily, Liu et al demonstrated the tetracycline removal from aqueous media at a pH range of 4–6, employing a Fe 3 O 4 -functionalized polyacrylonitrile electrospun membrane [ 60 ].…”

“…Among those, magnetic nanoparticles have been used as nanofillers in electrospun polymer-based fibrous membrane adsorbents, resulting in enhanced adsorption efficiency and providing the possibility for magnetic recovery by using an externally applied magnetic field. Examples include superparamagnetic fibrous adsorbents used in the removal of U(VI) [ 28 ], Eu(III) [ 29 ], Cr(VI) [ 30 ], arsenic ions [ 31 ], Congo red [ 26 ] and malachite green oxalate organic dyes [ 32 ], as well as antibiotics such as tetracycline [ 30 , 33 ], from synthetic aqueous media and urban wastewater (UWW). It was expected that the development of functionalized magnetic nanomaterials exhibiting high surface areas and high saturation magnetization such as magnetically functionalized graphene-based nanocomposites [ 34 ] would further promote the generation of highly effective magnetoactive adsorbents with potential to be used in water-remediation processes [ 35 , 36 , 37 , 38 , 39 ].…”

Comparative Study of the U(VI) Adsorption by Hybrid Silica-Hyperbranched Poly(ethylene imine) Nanoparticles and Xerogels

“…Intensive investigations performed recently led to the discovery of exceptional adsorbing substrates distinguished for both their specificity and effectiveness. The field extends from purely inorganic compounds such as carbon allotropes [11], metal oxides, and minerals [12] to organic-inorganic hybrids [11,13,14], composites [15,16], metal-organic frameworks (MOFs) [17][18][19], and aerogels [20][21][22]. Organic counterparts include conventional polymers [23,24], biopolymers [25,26], and dendritic polymers [27,28].…”

Design and Production of Functionalized Electrospun Fibers for Palladium Recovery

“…In one such example, we have developed magnetically functionalized fibrous adsorbents via electrospinning, consisting of random copolymers of the type poly(methyl methacrylate)-random-poly(2-(acetoacetoxy)-ethyl-methacrylate) (PMMA-co-PAEMA) bearing β-ketoester metal ion binding moieties, combined with poly(ethylene oxide) (PEO) and preformed oleic acid-coated magnetite nanoparticles that were successfully employed in the recovery of Eu(III). 22 In other studies of our group, pristine and magnetically functionalized polyvinylpyrrolidone (PVP)/ chitosan blended nanofibers have been successfully used as sorbents for U(VI) ions, 23,24 while the introduction of magnetic nanoparticles onto the fibers' surfaces resulted in an enhancement in the adsorption capacity of the nanocomposite fibrous adsorbents compared to that of the pristine fibrous analogues, reaching 183 mg/g. Thiourea-grafted electrospun polyacrylonitrile (PAN) fibers have been used for efficient Au(III) recovery from aqueous media.…”