N. P. Molochnikova

Solid extractants prepared with ionic liquids and their use for recovery of actinides from nitric acid solutions

Solid extractants were prepared by noncovalent immobilization of phosphonium ionic liquids (ILs) on various polymeric materials, including fibrous materials. These sorption materials can be used for recovering Pu from 0.5–5 M HNO3. Immobilization of phosphorus-containing ligands on solid supports using phosphonium ILs yields a material recovering actinides from nitric acid solutions.

Sorption preconcentration of radionuclides on Taunit carbon nanostructural material

The possibility of using Taunit carbon nanostructural material for sorption recovery of radionuclides from aqueous solutions was examined. Taunit efficiently recovers Am, Pu, Eu, U, and Tc from weakly acidic and neutral solutions. Taunit is a suitable support for preparing solid extractants based on a phosphonium ionic liquid and diphenyl(dibutylcarbamoylmethyl)phosphine oxide for recovery of actinides from nitric acid solutions.

Solid-phase extractants based on taunit carbon nanotubes for actinide and REE preconcentration from nitric acid solutions

The sorption properties of solid-phase extractants (SPEs) prepared by impregnation of Taunit carbon nanotubes with adducts of diphenyl(dibutylcarbamoylmethyl)phosphine oxide (CMPO) and tri-n-octylphosphine oxide (TOPO) in HNO3 solutions were studied. The SPEs exhibit high ability to sorb U(VI), Pu(IV), Np(V), Am(III), and Eu(III) from nitric acid solutions, with good kinetic properties. The impregnation conditions and distribution coefficients of the radionuclides in their recovery from 3 M HNO3 were determined. The possibility of preparing SPEs by Taunit impregnation in HNO3 solutions with adducts of tributyl phosphate (TBP) and N,N′-dimethyl-N,N′-dioctylhexylethoxymalonamide (DMDOHEMA) and with Cyphos IL-101 phosphonium ionic liquid was demonstrated.

Extraction and sorption preconcentration of U(VI), Am(III), and Pu(IV) from nitric acid solutions with alkylenediphosphine dioxides

The extraction of U(VI), Am(III), and Pu(VI) from nitric acid solutions in the form of complexes with alkylenebis(diphenylphosphine) dioxides and their sorption with POLIORGS F-6 sorbent prepared by noncovalent immobilization of methylenebis(diphenylphosphine) dioxide (MDPPD) on a KhAD-7M™ polymeric matrix were studied. The preconcentration conditions and distribution coefficients of U(VI), Am(III), and Pu(IV) in their sorption from 3 M HNO3 were determined. The possibility of concentrating actinides from multicomponent solutions was demonstrated. The composition and nature of complexes of U(VI) with MDPPD were determined from the 31P NMR data.

Sorption recovery of U(VI), Pu(IV), and Am(III) from nitric acid solutions with solid-phase extractants based on Taunit carbon nanotubes and polystyrene supports

Sorption procedures were developed for recovering U(VI), Pu(IV), and Am(III) with solid-phase extractants (SPEs) prepared by impregnation of Taunit carbon nanotubes and polystyrene supports with diphenyl( dibutylcarbamoylmethyl)phosphine oxide (CMPO) and tri-n-octylphosphine oxide (TOPO) The impregnation and actinide recovery were performed in the batch mode and using microcolumns. Procedures for support impregnation and SPE preparation are described. Conditions were found for sorption recovery of U(VI), Pu(IV), and Am(III) from 3 M HNO3 solutions. The possibility of actinide desorption was demonstrated. The effect of macrocomponents on the degree of actinide recovery was examined.

Preconcentration of uranium on POLIORGS 34-n fibrous filled sorbent from natural waters

Sorption preconcentration of U(VI) on POLIORGS 34-n fibrous filled sorbent with amidoxime groups from model solutions like natural water was studied under static and dynamic conditions. The equilibrium (distribution coefficient) and kinetic (diffusion coefficient) parameters of the sorption were determined. Parameters of dynamic preconcentration of uranium by sorption on disks and in a column packed with POLIORGS 34-n under indicated conditions were calculated by mathematical modeling using the experimental data.

Sorption of neptunium in the highest oxidation states from alkaline solutions with complexing fibrous “filled” sorbents

Sorption of Np(VII), Np(VI), and Np(V) from 1 M NaOH by complexing fibrous “filled” sorbents was examined. POLIORGS 33-n and 34-n sorbents containing amidoxime and hydrazidine groups efficiently recover Np in the highest oxidation states and exhibit good kinetic properties. During sorption, Np(VII) is reduced with the sorbent to Np(VI) having a higher, under the actual conditions, distribution coefficient. The distribution coefficients, ml g−1, were estimated at 4.6 × 103 for Np(VII), 1.4 × 104 for Np(VI), and 3.6 × 102 for Np(V).

New chelating sorbents based on materials filled with organophosphorus complexing agents

The chelating fibrous “filled” sorbents POLYORGS type with hydrazidine and amidoxime complexing groups (POLYORGS 33) and modified by reagent 3,6-bis-[(2-arsonophenyl)azo]-4,5-dihydroxy-2,7-naphtalen disulphoacid (Arsenazo-III) POLYORGS 33AIII pattern had been synthesized. The sorption ability of these materials were examined in the case of 241Am, 239Pu, 237Np, 233U, and 152Eu pre-concentration from simulated ground water solutions. It was found that all radionuclides above in indicator amounts (~10-5M) under preliminary experiments were recovered almost completely. POLYORGS 33 and POLYORGS 33AIII samples showed as well fast kinetics on the sorption process above. The derivatives of ethers of phosphoric acid, namely O-(2-alkyl)(diéthylcarbamoylmethyl)phenylphosphinates (O2ADECMPP), were synthesized and examined on liquid-liquid extraction of TRlPs, Lantanides and Tc (VII) from nitric acid solutions. A nonlinear increase of distribution coefficients (DM) as the function of the carbon radical extension on radionuclides extraction by O2ADECMPP solutions in meta-nitrobenzotriftoride (Ftoropol-723), or 1,2-dichlorethane had been found. Maximum of a distribution coefficients are found at n = 9 (R = CnH2n+1) for all radionuclides used. However in all further experiments easy available and equally efficient O2EHDECMPP reagent was used. It was shown that maxima of DM for Am(III), and Eu(III) extraction by 02EHDECMPP in 1,2-dichlorethane are at [HNO3]=3M ([R] = 0,1M; DAm = 1,45 and DEu = 1,02). For Pu(IV), and U(VI) extraction the increase of acid concentration in the range [HNO3] from 0.1M to 5M leads to the growth of the distribution coefficients, and at [R]=0,01M values of DPuchanges from 0.48 to 35, and for Du from 0.057 to 4.8. On the contrary, for Tc(VII) extraction by 02EHDECMPP in 1,2-dichlorethane the increase of HNO3 concentration in the solution causes noticeable slowing-down of the distribution coefficients, and DTc in the range [HNO3] from 0.1M to 5M decreases from 9.6 to 0.013 ([R] = 0,1M). Dependencies of the distribution coefficients for TRUs, Lantanides and Tc(VII) on reagent concentration were measured under 3M HNO3. For Am(III), Eu(III), and Tc(VII) it is shown that the increase of reagent concentration in the range [R] from 0.025M to 0.1M leads to the growth of the distribution coefficients for DAm from 0.057 to 1.45, for DEu from 0.055 to 1.02, and for DTc from 0.01 to 0.12. In the logarithm coordinates of DAm and DEu values on [R] dependence slope is close to two, upon which can be considered that extractable complex composition could be as Am.2R and Eu.2R. For Tc(VII) extraction the solvate number in the similar conditions is about 1.5. Probably, in the extraction system two different Tc complexes: mono- and bi-coordinated species were formed. For Pu(IV), and U(VI) it was shown that the increase of reagent concentration in the range [R] from 10-4M to 0.01M leads to the growth of the distribution coefficients for DPu from 0.08 to 11, for DU from 0.02 to 3.2. Values of a solvate number calculated from the slop of these plots above for Pu(IV) and U(VI) are close to one, and we considered that extractable complex composition for these elements could be as MR. For TRUs in comparison with extraction capacity of O2ADECMPP and well known phosphorous containing compounds the ratio has been obtain: DAm(TBP): DAm(Dialkylmethylphoshanates): DAm(02ADECMPP): DAm(Diphenyldibuthyl(carbamoylmethyl)phosphineoxide) = 1: 5.101: 2,5.104: 5.104. For Tc (VII) it was found that the best extractant for this element is O2ADECMPP. On the basis of O2ADECMPP compounds original chelating granulated sorbents were synthesized which were tested to respect of Pu(IV) isolation from nitric acid solutions.

Sorption recovery of radionuclides from alkaline solutions using fibrous “filled” sorbents

The possibility of using POLIORGS 33-n and 34-n fibrous “filled” sorbents with amidoxime groups for recovering U(VI), Am(III), and Pu(IV) from alkaline solutions of various compositions was studied. These sorbents exhibit high performance and excellent kinetic properties in recovery of uranium and transuranium elements from alkaline solutions. The distribution coefficients in their sorption from alkaline solutions at various (even high) values of pH and salt content were determined.

Sorption Recovery of Transplutonium Elements from Nitric Acid Solutions with Arsenazo Group Reagents

Sorption recovery of actinides and lanthanides from nitric acid solution with arsenazo group reagents, activated carbon modified with these reagents, and chelating sorbents containing arsenazo functional groups was studied.