Non-fission Products Research Articles

Extraction behavior of cesium and some typical fission and non-fission products with a new 1,3-di(1-decyloxy)-2,4-crown-6-calix[4]arene

Abstract A new macrocyclic supramolecular recognition agent, 1,3-di(1-decyloxy)-2,4-crown-6-calix[4]arene (DecylCalix[4]C6), was synthesized by a multistep reaction through separation and purification by column chromatography packed with silica gel. The extraction behavior of some representative fission and non-fission products such as La(III), Y(III), Cs(I), Rb(I), Pd(II), Mo(VI), Zr(IV), Sr(II), Ba(II), Ru(III), Na(I), and K(I), which were contained in highly active liquid waste (HLW), with DecylCalix[4]C6/1-octanol in HNO3 medium was investigated, in particular by examining the impact of contact time, the HNO3 concentration in the range of 0.4 to 5.0 M, and the temperature. DecylCalix[4]C6 showed excellent extraction ability and high selectivity for Cs(I) over the tested metals except for Rb(I). It was attributed to the effective recognition and complxation of DecylCalix[4]C6 for Cs(I). The optimum HNO3 concentration for the Cs(I) extraction was 3.0 M. The composition of the extracted species of Cs(I) with DecylCalix[4]C6 was determined to be (CsDecylCalix [4]C6)NO3. It is valuable for the effective partitioning of Cs(I) from highly active liquid waste with DecylCalix[4]C6 by liquid-liquid solvent extraction.

Synthesis and characterization of novel macroporous silica-polymer-calixcrown hybrid supramolecular recognition materials for effective separation of cesium

Two novel macroporous silica-polymer-calixcrown hybrid supramolecular recognition materials, 25,27-bis(n-octyloxy)calix[4]arene-crown-6 (BnOCalix[4]C6)/SiO2-P and 25,27-bis(i-octyloxy)calix[4]arene-crown-6 (BiOCalix[4]C6)/SiO2-P were synthesized by in situ polymerization and impregnation techniques. The obtained materials were characterized by scanning electron microscope (SEM), particle size distribution, nitrogen adsorption–desorption isotherms, thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR) spectroscopy, 29Si solid-state NMR, and powder X-ray diffraction (XRD). The adsorption of some typical fission and non-fission products Na(I), K(I), Rb(I), Cs(I), Sr(II), Ba(II), La(III), Y(III), Pd(II), Ru(III), Zr(IV), and Mo(VI) onto BnOCalix[4]C6/SiO2-P and BiOCalix[4]C6/SiO2-P in HNO3 solution was investigated. The bleeding of the materials in HNO3 solution was evaluated by analysis of total organic carbon (TOC). BnOCalix[4]C6/SiO2-P and BiOCalix[4]C6/SiO2-P exhibited excellent adsorption ability and high selectivity for Cs(I) over all the other tested metals.

Extraction of Cesium and Some Typical Metals with a Supramolecular Recognition Agent 1,3-Bis(1-nonyloxy)-2,4-crown-6-calix[4]arene

A macrocyclic supramolecular recognition agent, 1,3-bis(1-nonyloxy)-2,4-crown-6-calix[4]arene (NonCalix[4]C6), was synthesized. The extraction of Cs(I), a heat generator, and some typical fission and nonfission products, La(III), Y(III), Rb(I), Mo(VI), Zr(IV), Sr(II), Ba(II), Ru(III), Na(I), K(I), and Pd(II), with NonCalix[4]C6/1-octanol in HNO3 medium was investigated. The effects of contact time, the concentration of HNO3 in the range of (0.4 to 5.0) mol·kg–1, and temperature were evaluated. NonCalix[4]C6 showed excellent extraction ability and high selectivity for Cs(I) over the tested metals except Rb(I), which was ascribed to the effective recognition of NonCalix[4]C6 for Cs(I). The optimum acidity in the extraction of Cs(I) was 4.0 mol·kg–1 HNO3. The extraction property and mechanism of Cs(I) were discussed. The composition of the extracted species of Cs(I) with NonCalix[4]C6 was determined as CsNO3·NonCalix[4]C6. Valuable chemical engineering parameters in the extraction of Cs(I) were obtained. It is beneficial to effectively partition Cs(I) from highly active liquid waste with the NonCalix[4]C6/1-octanol extraction system.

The studies on absorption behavior of calix[4]-bis-crown-6 chromatographic resin and its application to the separation of HLW

In this paper, to separation Cs(I) effectively from HLW, a kind of chromatographic rein was synthesized through immobiling calix[4]-bis-crown-6 on the macroporous polystyrene -divinylbenzene polymeric material. The synthesized chromatographic resin showed high ability to absorb Cs(I). While the radioactive elements Pu(III), Np(V), U(VI), Th(IV), as well as all of the fission and non-fission products showed almost no sorption towards chromatographic rein. The separation of Cs from HLW can be realized through adjusting the valence of Np and Pu or adding H2C2O4. All the results showed that the application of the new chromatographic rein to the analysis of HLW is possible.

Preparation of macroporous silica-based crown ether materials for strontium separation

To develop a separation process of Sr(II), a macroporous silica-based 4,4′,(5′)-di(tert-butylcyclohexano)-18-crown-6 (DtBuCH18C6) polymeric material, (DtBuCH18C6+Oct)/SiO2-P, was synthesized by impregnating and immobilizing DtBuCH18C6 and 1-octanol into the pores of the macroporous SiO2-P particles support. DtBuCH18C6 was modified with 1-octanol through hydrogen bonding. The adsorption of simulant elements of some typical fission products Ru(III), Pd(II), Ba(II), Mo(VI), La(III), Y(III), Sr(II), Cs(I) and those of non-fission products Na(I) and K(I) onto (DtBuCH18C6+Oct)/SiO2-P were studied at 298 K. The effects of the HNO3 concentration in a range of 0.1–5.0 M and contact time on the adsorption were investigated. (DtBuCH18C6+Oct)/SiO2-P showed excellent adsorption ability and high selectivity for Sr(II) over all of the tested metals except Ba(II). Partitioning of Sr(II) from a 2.0 M HNO3 solution containing ~5.0 × 10−3 M of the tested metals was conducted utilizing (DtBuCH18C6+Oct)/SiO2-P packed column. Pd(II), Mo(VI), Y(III), La(III), Ru(III), K(I), Cs(I), and Na(I) showed no adsorption and flowed into effluent along with 2.0 M HNO3. Sr(II) was retained on (DtBuCH18C6+Oct)/SiO2-P and was eluted effectively by H2O, while Ba(II) showed similar elution behavior. The bleeding of total organic carbon leaked from (DtBuCH18C6+Oct)/SiO2-P was evaluated. It was demonstrated that the macroporous silica-based (DtBuCH18C6+Oct)/SiO2-P materials are promising in separation of Sr(II) from high level radioactive waste.

Chromatographic separation of cesium by a macroporous silica-based supramolecular recognition agent impregnated material

A novel macroporous silica-based supramolecular recognition compound 1,3-[(2,4-diethyl heptylethoxy)oxy]-2,4-crown-6-Calix[4]arene (Calix[4]arene-R14) polymeric composite (Calix[4] + Oct)/SiO 2-P was prepared. It was synthesized by impregnating and immobilizing a mixture of Calix[4]arene-R14 and n-octanol into the pores of the macroporous SiO 2-P particles. The adsorption of Cs(I) and some typical fission and non-fission products (FPs) contained in high level liquid waste (HLLW) such as Na(I), K(I), Cs(I), Rb(I), Sr(II), and Ba(II) onto (Calix[4] + Oct)/SiO 2-P was investigated by examining the influence of contact time and the HNO 3 concentration at 298 K. It was found that with an increase in the concentration of HNO 3, the adsorption of Cs(I) onto (Calix[4] + Oct)/SiO 2-P increased from 0.324 M to 4.0 M HNO 3 and then decreased to 7.0 M HNO 3. At the optimum HNO 3 concentration of 4.0 M HNO 3, (Calix[4] + Oct)/SiO 2-P showed excellent adsorption ability and high selectivity for Cs(I) over all of the tested elements except Rb(I). The chromatographic separation of Cs(I) from a simulated HLLW containing ∼5.0 mM of the tested elements was performed by (Calix[4] + Oct)/SiO 2-P packed column at 298 K. Na(I), K(I), Sr(II), and Ba(II) showed no adsorption and were eluted into effluent along with 4.0 M HNO 3. Cs(I) and Rb(I) adsorbed by (Calix[4] + Oct)/SiO 2-P could be effectively eluted with water and separated from the others. It is demonstrated that (Calix[4] + Oct)/SiO 2-P is promising to apply in the separation of Cs(I), one of the heat emitting nuclides, from an acidic HLLW by extraction chromatography.

SPEC Process III. Synthesis of a Macroporous Silica-Based Crown Ether-Impregnated Polymeric Composite Modified with 1-Octanol and its Adsorption Capacity for Sr(II) Ions and Some Typical Co-Existent Metal Ions

A macroporous silica-based 4,4′,(5′)-di(t-butylcyclohexano)-18-crown-6 (DtBuCH18C6)-impregnated polymeric composite, (DtBuCH18C6 + Oct)/SiO2-P, was synthesized by molecular modification of DtBuCH18C6 with 1-octanol through hydrogen bonding. This was achieved by impregnating and immobilizing DtBuCH18C6 and 1-octanol molecules in the pores of macroporous SiO2-P particles possessing a mean pore diameter of 50 μm. The adsorption of some fission and non-fission products contained in highly active liquid waste (HLW) such as Ru(III), Mo(VI), Pd(II), Na(I), K(I), Cs(I), Sr(II), Ba(II), La(III) and Y(III) onto (DtBuCH18C6 + Oct)/SiO2-P was investigated at 298 K. The effects of contact time and HNO3 concentration within the range 0.1–5.0 M were examined. Increasing the HNO3 concentration from 0.1 M to 2.0 M led to a significant increase in the adsorption of Sr(II), followed by a decrease when the HNO3 concentration was increased further to 5.0 M. The optimum concentration of HNO3 in the adsorption of Sr(II) onto (DtBuCH18C6 + Oct)/SiO2-P was determined as 2.0 M. For the other ions examined with the exception of Ba(II), very weak or almost non-existent adsorption capacities were observed at all HNO3concentrations. The leaching of total organic carbon (TOC) from (DtBuCH18C6 + Oct)/SiO2-P into the aqueous phase was evaluated. Over the HNO3 concentration range 0.1–3.0 M, the quantity of TOC leached was ca. 40 ppm compared with 355.8–373.3 ppm at HNO3 concentrations above 4.0 M. Significant reduction of TOC leaching from the macroporous silica-based DtBuCH18C6-impregnated polymeric composite was achieved in 2.0 M HNO3. Such behaviour could be of great benefit in using (DtBuCH18C6 + Oct)/SiO2-P for the partitioning of Sr(II) from HLW by extraction chromatography.

Modification of a novel macroporous silica-based crown ether impregnated polymeric composite with 1-dodecanol and its adsorption for some fission and non-fission products contained in high level liquid waste

A novel macroporous silica-based chelating polymeric composite, DtDo/SiO 2–P, was synthesized by molecular modification of 4,4′,(5′)-di-( tert-butylcyclohexano)-18-crown-6 (DtBuCH18C6) with a long carbon chain organic compound 1-dodecanol. It was performed through impregnation and immobilization of DtBuCH18C6 and 1-dodecanol molecules into the pores of the SiO 2–P particles. The adsorption of a few fission and non-fission product elements Sr(II), Ba(II), Cs(I), Ru(III), Mo(VI), Na(I), K(I), Pd(II), La(III), and Y(III) onto DtDo/SiO 2–P was investigated at 323 K. The effects of contact time and the HNO 3 concentration in a range of 0.1–4.0 M were investigated. It was found that at the optimum concentration of 2.0 M HNO 3, DtDo/SiO 2–P exhibited strong adsorption ability and excellent selectivity for Sr(II) over all of the tested elements, which showed very weak or almost no adsorption except Ba(II). The bleeding of total organic carbon (TOC) from DtDo/SiO 2–P was evaluated. The quantity of TOC in aqueous phase increased with an increase in HNO 3 concentration in terms of a linear equation [TOC] = 35.82[HNO 3] + 115.5 with a correlation coefficient of 0.9751. The TOC content leaked from DtDo/SiO 2–P modified by 1-dodecanol, 119.0–269.3 ppm, in the range of 1.0–4.0 M HNO 3 was significantly lower than that of 424.8–634.6 ppm in the case without modification. It resulted from the intermolecular interaction force of DtBuCH18C6 and 1-dodecanol through hydrogen bonding. The reduction of DtBuCH18C6 leakage by molecular modification was achieved. It is of great benefit to application of DtDo/SiO 2–P in partitioning of Sr(II), one of the main heat generators, from high level liquid waste (HLLW) in reprocessing process of nuclear spent fuel in MAREC (Minor Actinides Recovery from HLLW by Extraction Chromatography) process developed.

Impregnation synthesis of a novel macroporous silica-based crown ether polymeric material modified by 1-dodecanol and its adsorption for strontium and some coexistent metals

4,4′,(5′)-Di-( tert-butylcyclohexano)-18-crown-6(DtBuCH18C6) is a chelating agent having high selectivity mostly for Sr(II). To significantly reduce its leakage by molecular modification, a macroporous silica-based DtBuCH18C6 polymeric composite (DtDo/SiO 2–P) was synthesized. It was performed by impregnating and immobilizing DtBuCH18C6 and 1-dodecanol molecules into the pores of the SiO 2–P particles utilizing an advanced vacuum sucking technique. The adsorption of a few fission and non-fission products Sr(II), Ba(II), Cs(I), Ru(III), Mo(VI), Na(I), K(I), Pd(II), La(III), and Y(III) onto DtDo/SiO 2–P was investigated. It was done by examining the effects of contact time and the HNO 3 concentration in a range of 0.1–5.0 M at 298 K. At the optimum concentration of 2.0 M HNO 3, DtDo/SiO 2–P exhibited strong adsorption ability and high selectivity for Sr(II) great over all of the tested elements, which showed very weak or almost no adsorption except Ba(II). Meanwhile, It was found that the quantity of total organic carbon (TOC) leaked from DtDo/SiO 2–P in 2.0 M HNO 3, 187.5 ppm, was lower than 658.4 ppm that leaked from DtBuCH18C6/SiO 2–P, which was not modified. This was ascribed to the effective association of DtBuCH18C6 and 1-dodecanol through intermolecular interaction. The reduction of DtBuCH18C6 leakage by molecular modification with 1-dodecanol was achieved. It was of great benefit to application of DtDo/SiO 2–P in chromatographic partitioning of Sr(II), one of the main heat generators, from high level liquid waste (HLLW) in reprocessing of nuclear spent fuel in the MAREC (Minor Actinides Recovery from HLLW by Extraction Chromatography) process developed recently.

Development of the chromatographic partitioning of cesium and strontium utilizing two macroporous silica-based calix[4]arene-crown and amide impregnated polymeric composites: PREC partitioning process

To partition effectively Cs(I) and Sr(II), two harmful heat emitting nuclides, from a highly active liquid waste by extraction chromatography, two kinds of macroporous silica-based polymeric materials, Calix[4]arene-R14/SiO 2-P and TODGA/SiO 2-P, were synthesized. Two chelating agents, 1,3-[(2,4-diethyl-heptylethoxy)oxy]-2,4-crown-6-calix[4]arene (Calix[4]arene-R14), an excellent supramolecular compound having molecular recognition ability for Cs(I), and N, N, N′, N′-tetraoctyl-3-oxapentane-1,5-diamide (TODGA) were impregnated and immobilized into the pores of SiO 2-P particles support by a vacuum sucking technique. The loading and elution of 11 typical simulated fission and non-fission products from 4.0 M or 2.0 M HNO 3 were performed at 298 K. It was found that in the first column packed with the Calix[4]arene-R14/SiO 2-P, all of the simulated elements were separated effectively into two groups: (1) Na(I), K(I), Sr(II), Fe(III), Ba(II), Ru(III), Pd(II), Zr(IV), and Mo(VI) (noted as Sr-group); (2) Cs(I)–Rb(I) (Cs-group) by eluting with 4.0 M HNO 3 and distilled water, respectively. The harmful element Cs(I) flowed into the second group along with Rb(I) because of their close sorption and elution properties towards Calix[4]arene-R14/SiO 2-P, while Sr(II) showed no sorption and flowed into Sr-containing group. In the second column packed with TODGA/SiO 2-P, the Sr-group was separated into (1) Ba(II), Ru(III), Na(I), K(I), Fe(III), and Mo(VI) (non-sorption group); (2) Sr(II); (3) Pd(II); and (4) Zr(IV) by eluting with 2.0 M HNO 3, 0.01 M HNO 3, 0.05 M DTPA–pH 2.5, and 0.5 M H 2C 2O 4, respectively. Sr(II) adsorbed towards TODGA/SiO 2-P flowed into the second group and showed the excellent separation efficiency from others. Based on the elution behavior of the tested elements, an advanced PREC (Partitioning and Recovery of two heat generators from an acidic HLW (high activity liquid waste) by Extraction Chromatography) process was proposed.

Molecular modification of a novel macroporous silica-based impregnated polymeric composite by tri- n-butyl phosphate and its application in the adsorption for some metals contained in a typical simulated HLLW

Using tri- n-butyl phosphate (TBP) as a molecular modifier, a novel macroporous silica-based 4,4′,(5′)-di-( tert-butylcyclohexano)-18-crown-6 (DtBuCH18C6) polymeric composite (DtBuCH18C6 + TBP/SiO 2–P) was synthesized. It was done by impregnating and immobilizing DtBuCH18C6 and TBP molecules into the pores of SiO 2–P particles utilizing an advanced vacuum sucking technique. The adsorption of 10 fission and non-fission products Sr(II), Ba(II), Ru(III), Mo(VI), Na(I), K(I), Pd(II), La(III), Cs(I), and Y(III) onto (DtBuCH18C6 + TBP)/SiO 2–P was investigated by examining the influence of contact time and the HNO 3 concentration in a range of 0.1–5.0 M at 298 K. It was found that at the optimum concentration of 2.0 M HNO 3 (DtBuCH18C6 + TBP)/SiO 2–P exhibited strong adsorption ability and high selectivity for Sr(II) over all of the tested elements, which showed very weak or almost no adsorption except Ba(II). Moreover, the quantity of DtBuCH18C6 leaked from (DtBuCH18C6 + TBP)/SiO 2–P in 2.0 M HNO 3, 326.2 ppm, was obviously lower than 658.4 ppm that leaked from DtBuCH18C6/SiO 2–P. This was ascribed to the effective association of DtBuCH18C6 and TBP through intermolecular interaction, i.e., hydrogen bonding. The significant reduction of DtBuCH18C6 leakage by molecular modification with TBP was achieved. It was of great benefit to application of the (DtBuCH18C6 + TBP)/SiO 2–P polymeric composite in chromatographic partitioning of Sr(II), one of the main heat generators, from high level liquid waste (HLLW) in reprocessing of nuclear spent fuel in MAREC process developed recently.

Group partitioning of minor actinides and rare earths from highly active liquid waste by extraction chromatography utilizing two macroporous silica-based impregnated polymeric composites

Through an advanced vacuum sucking technique, two macroporous silica-based N, N, N′, N′-tetraoctyl-3-oxapentane-1,5-diamide (TODGA) and octyl(phenyl)- N, N-diisobutylcarbamoyl-methylphoshine oxide (CMPO) polymeric composites, TODGA/SiO 2-P and CMPO/SiO 2-P, were synthesized by impregnating and immobilizing the chelating agents into the pores of the SiO 2-P particles. To partition long-lived minor actinides (MA(III)), such as Am(III) and Cm(III) from highly active liquid waste (HLW), the loading and elution of 15 typically simulated fission and non-fission products from a 3.0 M HNO 3 were performed. In the first column packed with TODGA/SiO 2-P, the simulated elements were effectively separated into following groups: (1) non-adsorption group, (2) MA– lRE–FPs group, (3) hRE group, and (4) micro quantity of Zr(IV). MA(III) was predicted to flow into the second group along with Nd(III) due to their close adsorption and elution onto TODGA/SiO 2-P. In the second column packed with CMPO/SiO 2-P, after conditioning the acidity in MA– lRE–FPs containing 0.05 M DTPA to 3.0 M HNO 3, it was separated into (1) Sr(II) and Pd(II), (2) MA– mRE, (3) lRE, and (4) Zr(IV). MA(III) was believed to flow into MA– mRE effluent along with Gd(III) because of the similar adsorption towards CMPO/SiO 2-P. In terms of the position of MA(III) appeared, an improved MAREC process for long-lived MA(III) partitioning from HLW was proposed.

Removal of Pd(II), Zr(IV), Sr(II), Fe(III), and Mo(VI) from simulated high level liquid waste by extraction chromatography utilizing the macroporous silica-based polymeric materials

To eliminate a few specific elements from highly active liquid waste (HLW), two macroporous silica-based N, N, N′, N′-tetraoctyl-3-oxapentane-1,5-diamide (TODGA) and octyl(phenyl)- N, N-diisobutylcarbamoylmethylphosphine oxide (CMPO) impregnated polymeric composites, TODGA/SiO 2-P and CMPO/SiO 2-P, were synthesized. It was done by an advanced vacuum sucking technique through impregnation of the chelating agents into the pores of SiO 2-P particles support. The partitioning of Sr(II), Pd(II), Zr(IV), Mo(VI), and Cs(I) from a 3.0 M HNO 3 solution containing some typically simulated fission and non-fission products Ru(III), Rb(I), Fe(III), Na(I), K(I), and Ba(II) was performed at 298 and 323 K, respectively. In the first column packed with TODGA/SiO 2-P, Sr(II), Pd(II), and Zr(IV) were adsorbed and eluted effectively by 0.01 M HNO 3, 0.05 M DTPA-pH 2.5, and 0.5 M oxalic acid, respectively, while others showed very weak or almost no adsorption and flowed into effluent along with 3.0 M HNO 3. Cs(I), Fe(III), and Mo(VI) containing effluent was then applied to the second column packed with CMPO/SiO 2-P. Fe(III) and Mo(VI) were found to be adsorbed together and eluted utilizing 0.05 M DTPA-pH 2 at 323 K. The effective partitioning of Fe(III) was of great benefit to the evaporation, concentration, and finally geological disposal of HLW. The separation of Sr(II) and Mo(VI) was useful for the vitrification of HLW due to the Sr heat generator property and low solubility of Mo oxides in molten glass materials. Cs(I) can be separated by a novel silica-based 1,3-[(2,4-diethyl-heptylethoxy)oxy]-2,4-crown-6-calix[4]arene (Calix[4]arene-R14) impregnated polymeric composite (Calix[4]arene-R14/SiO 2-P). In terms of the results obtained, a highly specific partitioning process of Fe(III) and some specific fission products Sr(II), Pd(II), Zr(IV), Cs(I), and Mo(VI) from a simulated HLW by extraction chromatography was proposed.

The occurrence of delayed-neutron precursors

A survey of the isotope tables for delayed-neutron precursors has been made for odd- Z nuclei having neutron numbers greater than the magic numbers by either two or three. The quantity Q β – B n was calculated for each case from known data or from energy systematics to determine if neutron emission is energitically possible. Among the fourteen non-fission products examined, two are known delayed-neutron precursors. In only one other case, namely 81 209Tl, is there a possibility of delayed-neutron emission. The sixteen fission products considered include four known precursors, two nuclei previously suggested as precursors and three uncertain cases. In all the other cases delayed-neutron emission is energetically impossible.