Advanced Uranium Removal with Pure, Nonfluorinated Ionic Liquids: Fine-Tuning Hydrophilic and Hydrophobic Properties for Enhanced Selectivity.

Ionic liquids (ILs) have significant potential for eco-friendly extraction of uranium from aqueous solutions, which is critical for nuclear technology, fuel cycle management, and environmental protection. This study examines the impact of the adjustable hydrophobic/hydrophilic properties of ILs on the removal of uranium(VI) (UO22+) from aqueous solutions utilizing both a novel hydrophilic IL (1-butoxyethyl-1-methylmorpholinium butoxyethylphosphite - Mor1-2O4-BOEP) and 1-heptyl-1-methylmorpholinium heptylphosphite (Mor1-7-HP) as an example of a hydrophobic IL with a similar structure. The transfer mechanism of uranyl ions from water to organic or solid phases closely depends on the physicochemical properties of ILs, especially their hydrophobicity. The hydrophobic Mor1-7-HP extracts uranyl via neutral complex formation as UO2(NO3)2-(Mor1-7-HP)2. Conversely, hydrophilic Mor1-2O4-BOEP induced selective precipitation as UO2(NO3)-(BOEP), transferring uranyl to the solid phase. Optimization of the working parameters, in terms of acidity of the aqueous solution and amount of ILs used, allowed the extraction of over 98% of U(VI). The stoichiometry of the organic complex and the precipitate was determined using physicochemical techniques. These tunable H-phosphonate-based ILs have advantages over traditional solvent extraction and conventional ILs, allowing easier handling, improved selectivity, and lower environmental impact. This work advances uranium separation techniques with applications in hydrometallurgy, particularly in the treatment of wastewater and radioactive waste for sustainable uranium recovery.

Enhanced Electrochemical Performance in Supercapacitors through KCu-Cy Based Metal-Organic Framework Electrodes.

In the realm of electronics and electric energy storage, the convergence of organic and metallic materials has yielded promising outcomes. In this study, we introduce a novel metal-organic polymer synthesized from Cyamelurate and copper (KCu-Cy) and explore its application as an electrode for a supercapacitor. This material was pressed onto a stainless-steel grid as a thin film and synthesized on nickel foam. Comprehensive characterization was carried out to confirm the synthesis, ensure phase purity, and investigate atomic interactions. Single Crystal X-ray Diffraction (SCXRD) and Powder X-ray Diffraction (PXRD) analyses verified the synthesis and phase purity, shedding light on atomic arrangements. Fourier Transform Infrared Spectroscopy (FTIR) analyses provided insights into characteristic peaks within the material. Thermal Gravimetric Analysis (TGA) gauged stability and durability. Electrochemical performance was assessed through cyclic voltammetry. Notably, the nickel-supported electrodes, devoid of binders, exhibited exceptional specific capacity, reaching 1210.89 F/g at a scan rate of 5 mV/s, in contrast to 363.73 F/g for the pressed thin film on the stainless-steel grid, which incorporated a conductive agent and binder. Cu-Cy displayed impressive cyclization resistance, with a capacity retention of 90 % even after 11000 cycles. These findings underline the promise of Cu-Cy as a high-performance electrode material for supercapacitors, particularly in binder-free configurations, and suggest its potential in advanced energy storage applications.

Effect of Crystal Morphology on Electrochemical Performances of IRH-2 and IRH-2/PANI Composite for Supercapacitor Electrodes.

In the context of recent progress in designing metal-organic framework (MOF)-based supercapacitor electrodes, we report herein the successful growth of two different crystal morphologies of a cerium-based MOF, octahedral crystals named IRH-2-O and elongated square-bipyramidal crystals named IRH-2-ESBP (IRH = Institute de Recherche sur l'Hydrogène). The identical crystal structure of both materials was confirmed by powder X-ray diffraction (PXRD). Furthermore, scanning electron microscopy and energy-dispersive X-ray mapping analysis corroborated this fact and showed the crystal shape variation versus the surface composition of synthesized materials. Fourier transform infrared spectroscopy, UV-vis spectroscopy, and PXRD were used to confirm the purity of pristine MOFs as well as desired MOF//PANI composites. Cyclic voltammetry and electrochemical impedance spectroscopy highlighted the effect of crystal shape on the electrochemical performance of IRH-2 MOFs; the specific capacitance tripled from 43.1 F·g-1 for IRH-2-O to 125.57 F·g-1 for IRH-2-ESBP at 5 mV·s-1. The cycling stability was notably ameliorated from 7 K for IRH-2-O to 20 K for IRH-2-ESBP. Regarding the composites, the cell voltage was notably ameliorated from 1.8 to 1.95 V. However, the electrochemical performance of IRH-2/PANI composites was drastically decreased due to instability in the acidic media. To the best of our knowledge, our work is the first work that related the MOF crystal shape and the electrochemical performance.

Highly efficient extraction and selective separation of uranium (VI) from transition metals using new class of undiluted ionic liquids based on H-phosphonate anions.

In this paper, we report the development of an environmental friendly process to decontaminate uranium-containing ores and nuclear wastes by using non-fluorinated ionic liquids (ILs). The main advantages of this extraction process are the absence of any organic diluent and extra extraction agents added to the organic phase. Moreover, the process is cost-effective and maybe applied as a sustainable hydrometallurgical method to recover uranium. The distribution ratio (DU) and the extraction efficiency (%E) of uranium(VI) (UO22+) were found to be dependent on the acidity of the aqueous phase, the extraction time, the alkyl chain length in the ILs, the concentration of the aqueous feed and molar quantity of ILs. The DU value is higher than 600 and the %E is equal to 98.6% when [HNO3]=7M. The extraction reactions follows a neutral partition or ionic exchange mechanism depending on nitric acid concentration. The nature of bonding in the extracted complexes was investigated by spectroscopic techniques. The potential use of Mor1-8-OP for the separation of UO22+ from a mixture containing transition metal ions Mn+ was also examined. The UO22+ ions were separated and extracted efficiently. These ILs are promising candidates for the recovery and separation of uranium.

Physicochemical characterizations of novel dicyanamide-based ionic liquids applied as electrolytes for supercapacitors.

Novel ionic liquids (ILs), containing a dicyanamide anion (DCA-), are synthesized and applied as suitable electrolytes for electrochemical double layer capacitors (EDLCs). The prepared ILs are either composed of triethyl-propargylammonium (N222pr +) or triethyl-butylammonium (N2224 +) cations paired with the DCA- anion. The structure of the cation influences its electrostatic interaction with the DCA- anion and highly impacts the physical and electrochemical properties of the as-prepared ILs. The geometry and the length of the alkyl chain of the propargyl group in N222pr + enhance the ionic conductivity of N222pr-DCA (11.68 mS cm-1) when compared to N2224-DCA (5.26 mS cm-1) at 298 K. It is demonstrated that the Vogel-Tammann-Fulcher model governs the variations of the transport properties investigated over the temperature range of 298-353 K. A maximum potential window of 3.29 V is obtained when N222pr-DCA is used as electrolyte in a graphene based symmetric EDLC system. Cyclic voltammetry and galvanostatic measurements confirm that both electrolytes exhibit an ideal capacitive behavior. The highest specific energy of 55 W h kg-1 is exhibited in the presence of N2224-DCA at a current density of 2.5 A g-1.