TRPO Impregnated Levextrel Resin: Synthesis and Extraction Behavior of Zr (IV) and Nd (III) Ions

Theoretical and experimental studies on uranium(vi) adsorption using phosphine oxide-coated magnetic nanoadsorbent

In this study, novel Cyanex-923-coated magnetite nanoparticles (Fe3O4@Cyanex-923) were prepared, comprehensively characterized, and employed for uranium(vi) ion adsorption from aqueous solutions. FTIR and TGA data confirmed that Fe3O4 has successfully gained Cyanex-923 surface functionality. Particle size and morphological studies via DLS, HR-TEM, and SEM showed uniform-dispersed quasi-spherical nanoparticles with a mean diameter of ca. 44 nm. Magnetism measurement data revealed the superparamagnetic properties of the Fe3O4@Cyanex-923 nanoadsorbent. The effect of different experimental settings on the adsorption efficiency was studied to determine the best operational conditions. The experimental results were analyzed using Langmuir, Freundlich, and Temkin isotherms; where the adsorption data obeyed the Langmuir model showing a theoretical adsorption capacity of 429.185 mg g-1 at 298 K. Kinetics data analysis revealed a fast adsorption process that could reach equilibrium within 60 min and is well-fitted to the pseudo-2nd-order model. Temperature affected the adsorption process and the thermodynamic data indicated that uranium(vi) adsorption was spontaneous and exothermic. Fe3O4@Cyanex-923 nanoparticles displayed a good regeneration behavior over three sequential adsorption-desorption cycles. The Fe3O4@Cyanex-923 nanoadsorbent showed a high uranium adsorption capacity, fast equilibration time, economic nature, good reusability, and easy separation; making it a promising candidate for uranium(vi) removal from nuclear waste streams.

Kinetics Study of Solvent and Solid-Phase Extraction of Rare Earth Metals with Di-2-Ethylhexylphosphoric Acid

The kinetic features of solvent and solid-phase extraction of yttrium and iron (III) from simulated and industrial phosphoric acid solutions are revealed. Di-2-ethylhexylphosphoric acid (D2EHPA) was used as a liquid extractant, and D2EHPA-containing Levextrel resin—a co-polymerization product of styrene and divinylbenzene in the presence of D2EHPA—was used as a solid-phase extraction agent. Significant dependence of yttrium extraction rate constant on the stirring rate was revealed using the formal first-order kinetic equation. The data obtained characterizes a diffusion-limited process with an activation energy of 16.2 ± 1.3 kJ/mol. Temperature increase during the iron (III) extraction process leads to a changeover of a rate-limiting stage from kinetic to diffusion, accompanied by drop of activation energy from 40.0 ± 1.4 to 11.4 ± 1.2 kJ/mol. Effective separation of elements at the extraction stage is possible at temperatures of 283–300 K under non-equilibrium conditions of the ferric ions transport from aqueous to organic phase. This condition ensures a high yttrium–iron separation coefficient of 23.2 in 1.5–2 min. Extraction kinetics by Levextrel resin are described by Fick’s second law equation, which establishes the laws of diffusion in the solid grain of the organic phase with an activation energy of 18.5 ± 2.0 kJ/mol.

New insights into the uranium adsorption behavior of mesoporous SBA-15 silicas decorated with alkylphosphine oxide ligands

Alkylphosphine oxide functionalized mesoporous silicas were prepared by co-condensation and further addition reaction with secondary n-propylphosphine oxide and are promising candidates for the preconcentration and adsorption of uranium from acidic aqueous solutions.