Adsorption Behavior of Sr(II) and some Typical Co‐existent Metals Contained in High Level Liquid Waste onto a Modified Macroporous Silica‐Based Polymeric DtBuCH18C6 Composite

To significantly reduce the bleeding of 4,4′,(5′)‐di(tert‐butylcyclohexano)‐18‐crown‐ 6 (DtBuCH18C6), an improved novel macroporous silica‐based polymeric composite (DtBuCH18C6+TBP)/SiO₂‐P was synthesized. It was performed by impregnating and immobilizing DtBuCH18C6 into the pores of the SiO₂‐P particles via the molecular modification of DtBuCH18C6 with a tri‐n‐butyl phosphate (TBP) through hydrogen bonding. The adsorption of a few typical simulated fission and non‐fission products Pd(II), La(III), Na(I), K(I), Sr(II), Ba(II), Ru(III), Cs(I), Mo(VI), and Y(III) onto (DtBuCH18C6+TBP)/SiO₂‐P was investigated at 323 K. It was done by examining the effect of contact time and the HNO₃ concentration in a range of 0.1–5.0 M. Sr(II), one of the main heat emitting nuclides, showed optimum adsorption onto (DtBuCH18C6+TBP)/SiO₂‐P in 2.0 HNO₃, while others showed very weak or almost no adsorption except a portion of Ba(II). The leaching of TBP and DtBuCH18C6 from (DtBuCH18C6+TBP)/SiO₂‐P was evaluated. The average content of DtBuCH18C6, 298.7 ppm, leached from (DtBuCH18C6+TBP)/SiO₂‐P in 2.0 M HNO₃ at 323 K was obviously lower than that of 797.3 ppm leached from DtBuCH18C6/SiO₂‐P at 298 K. The significant reduction of DtBuCH18C6 leaching from its macroporous silica‐based polymeric adsorbent was achieved. It is useful for the recycle operation of the silica‐based DtBuCH18C6 impregnated polymeric composite in chromatographic partitioning of Sr(II) from high level liquid waste (HLLW).     

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/SiO₂–P) was synthesized. It was performed by impregnating and immobilizing DtBuCH18C6 and 1-dodecanol molecules into the pores of the SiO₂–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/SiO₂–P was investigated. It was done by examining the effects of contact time and the HNO₃ concentration in a range of 0.1–5.0 M at 298 K. At the optimum concentration of 2.0 M HNO₃, DtDo/SiO₂–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/SiO₂–P in 2.0 M HNO₃, 187.5 ppm, was lower than 658.4 ppm that leaked from DtBuCH18C6/SiO₂–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/SiO₂–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.     

Synthesis of a Novel Macroporous Silica-Calix[4]arene-Crown Supramolecular Recognition Material and its Adsorption for Cesium and some Typical Metals in Highly Active Liquid Waste

Abstract

A novel macroporous silica-based 25,27-bis(iso-propyloxy)calix[4]arene-26,28-crown-6 (BiPCalix[4]C6) supramolecular recognition material, BiPCalix[4]C6/SiO₂-P, was synthesized. It was prepared by impregnation and the immobilization of the BiPCalix[4]C6 molecule into the pores of the macroporous SiO₂-P particles. The adsorption of Cs(I) and some typical elements Na(I), K(I), Rb(I), Sr(II), Ba(II), Ru(III), Mo(VI), La(III), and Y(III) onto the BiPCalix[4]C6/SiO₂-P material was investigated. The effects of the HNO₃ concentration, contact time, and temperature on the adsorption of the tested metals were studied. It was found that at the optimum concentration of 3.0 M HNO₃, BiPCalix[4]C6/SiO₂-P exhibited excellent adsorption ability and high selectivity for Cs(I) over all the tested elements, which showed weak or almost no adsorption except Rb(I). A pseudo-second-order model was found to be able to describe the adsorption kinetics of Cs(I). The chemical complexation of Cs(I) with BiPCalix[4]C6/SiO₂-P was considered to be the rate-controlling step. Meanwhile, the thermodynamic parameters of the Cs(I) adsorption, ΔH?, ΔG?, and ΔS? were determined. The adsorption of Cs(I) onto BiPCalix[4]C6/SiO₂-P was exothermic. It was demonstrated that in 3.0 M HNO₃, the novel macroporous BiPCalix[4]C6/SiO₂-P material shows promise for the partitioning of Cs(I) from highly active liquid waste.     

Adsorption of Some Typical Fission Products onto a Novel Macroporous Silica-based Dialkyl Derivative of Pyridine Impregnated Material

A macroporous silica-based multidentate soft-ligand 2,6-bis(5,6-di(iso-hexyl)-1,2,4-triazine-3-yl)pyridine (BDIHTP) material, BDIHTP/SiO₂-P, was synthesized by impregnating and immobilizating BDIHTP into the pores of the SiO₂-P particles. The adsorption behavior of some typical fission products Mo(VI), Zr(IV), Ru(III), Pd(II), Rh(III), and a part of rare earths La(III), Ce(III), Nd(III), Eu(III), Gd(III), Dy(III), Er(III), Yb(III), and Y(III) contained in highly active liquid waste (HLW) onto BDIHTP/SiO₂-P was investigated. The effects of contact time and the concentration of HNO₃ in the range of 0.3 M to 5.0 M were examined. The BDIHTP/SiO₂-P materials showed excellent adsorption ability and high selectivity for Pd(II) greater than all of the tested metals. It was contributed to the effective complexation of Pd(II), a soft-Lewis acid and an electron-pair acceptor, with BDIHTP, a soft-Lewis base and an electron-pair donor. The chromatographic partitioning of the tested metals from 1.0 M HNO₃ by BDIHTP/SiO₂-P packed column was performed. Pd(II) was effectively eluted with 0.2 M thiourea-0.1 M HNO₃ and then separated from the others. The results are beneficial to partitioning of the long-lived minor actinides and Pd(II) together from HLW by the BDIHTP/SiO₂-P materials.     

Adsorption Behaviors of Platinum Group Metals in Simulated High Level Liquid Waste Using Macroporous (MOTDGA-TOA)/SiO2-P Silica-based Absorbent

As fundamental research for separation of platinum group metals (PGMs) from high level liquid waste (HLLW) by macroporous silica-based adsorbent, (MOTDGA-TOA)/SiO₂-P adsorbent was prepared by impregnation of N,N′-dimethyl-N,N′-di-n-octyl-thiodiglycolamide (MOTDGA) and Tri-n-octylamine (TOA) into silica/polymer composite support (SiO₂-P). The adsorption behavior of Ru(III), Rh(III), and Pd(II) in simulated HLLW onto the adsorbent were investigated by the batch method to obtain their corresponding equilibrium and kinetic data. The adsorbent showed strong adsorption for Pd(II) and the adsorption reached equilibrium within 2 hr. High distribution coefficient (K _d) values for Pd(II) were obtained in 0.1–1 M HNO₃ concentration. In addition, the use of both MOTDGA and TOA improved adsorption of Ru(III) and Rh(III) better than individual use of them. Especially, the K _d value for Ru(III) towards (MOTDGA-TOA)/SiO₂-P adsorbent was three times larger than that in the adsorption using only with MOTDGA or TOA as extractant. The adsorptions of Ru(III), Rh(III), and Pd(II) followed the Langmuir adsorption model, and were found to be controlled by the chemisorption mechanism.     

Preparation of a Macroporous Silica-Based Multidentate Soft-Ligand Material and its Application in the Adsorption of Palladium and the Others

To separate Pd(II), a macroporous silica-based soft-ligand 2,6-bis(5,6-di(iso-butyl)-1,2,4-triazine-3-yl)pyridine (BDIBTP) material, BDIBTP/SiO₂-P, was synthesized by vacuum treatment. It was a multidentate chelating composite prepared by impregnation and immobilization of BDIBTP and 1-octanol molecules into the pores of the macroporous SiO₂-P particles with a mean diameter of 50 µm. 1-Octanol was used to modify BDIBTP through intermolecular interaction force. The adsorption of some typical fission products Zr(IV), Pd(II), La(III), Y(III), Ru(III), Rh(III), and Mo(VI) contained in highly active liquid waste (HLW) onto the BDIBTP/ SiO₂-P materials was investigated. It was carried out by examining the effects of contact time and the concentration of HNO₃ in the range of 0.3 M?7.0 M. BDIBTP/SiO₂-P showed excellent adsorption ability and high selectivity for Pd(II) over all of the tested metals. It was ascribed to the effective complexation of Pd(II) with BDIBTP/SiO₂-P. Consideration of the complexation of BDIBTP for minor actinides MAs(III), the possibility and feasibility of effective partitioning of Pd(II) and MAs(III) simultaneously from a simulated HLW were discussed. A new concept process entitled MPS for the MA(III) and Pd(II) Separation has been proposed.     

SPEC: A New Process for Strontium and Cesium Partitioning Utilizing Two Macroporous Silica-Based Supramolecular Recognition Agents Impregnated Polymeric Composites

Abstract

To effectively separate two heat generators Cs(I) and Sr(II) from a highly active liquid waste (HLW), two macroporous silica-based polymeric composites (Calix[4]arene-R14 + M)/SiO₂-P and (DtBuCH18C6 + M)/SiO₂-P were synthesized. It was done by impregnating and immobilizing the supramolecular recognition agent, 1,3-[(2,4-diethylheptyl ethoxy)oxy]-2,4-crown-6-calix[4]arene (Calix[4]arene-R14) or 4,4′,(5′)-di-(tert-butylcyclo hexano)-18-crown-6 (DtBuCH18C6), into the pores of the macroporous SiO₂-P particles with a mean diameter of 50 µm. It was found that in the first column packed with (Calix[4]arene-R14 + M)/SiO₂-P, all of the tested elements were effectively eluted and separated into two groups: (1 Horwitz , E.P. ; Mark , L.D. ; Fisher , D.E. ( 1991 ) SREX: A new process for the extraction and recovery of strontium from acidic nuclear waste stream . Solvent Extr. Ion Exch. , 9 ( 1 ): 1 – 25 .[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]) Na(I), K(I), Sr(II), Ba(II), Rh(III), Ru(III), Pd(II), Zr(IV), RE(III) (La-Lu and Y), and Mo(VI) (Sr-containing group), and (2 Wood , D.J. ; Law , J.D. ( 1997 ) Evaluation of the SREX solvent extraction process for the removal of ⁹⁰Sr and hazardous metal ions from acidic nuclear waste solutions containing high concentrations of interfering alkali metal ions . Sep. Sci. Technol. , 32 ( 1–4 ): 241 – 253 .[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]) Cs(I)-Rb(I) (Cs-group) by eluting with 4.0 M HNO₃ and water, respectively, at 298 K. The heat emitting element Cs(I) flowed into the second group along with Rb(I), while Sr(II) showed no sorption and flowed into the Sr-containing group. In the second column packed with (DtBuCH18C6 + M)/SiO₂-P, the Sr-containing group was separated into (1 Horwitz , E.P. ; Mark , L.D. ; Fisher , D.E. ( 1991 ) SREX: A new process for the extraction and recovery of strontium from acidic nuclear waste stream . Solvent Extr. Ion Exch. , 9 ( 1 ): 1 – 25 .[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]) Na(I), K(I), Rh(III), Ru(III), RE(III) (La-Lu and Y), Pd(II), Zr(IV), and Mo(VI) (non-sorption group), and (2 Wood , D.J. ; Law , J.D. ( 1997 ) Evaluation of the SREX solvent extraction process for the removal of ⁹⁰Sr and hazardous metal ions from acidic nuclear waste solutions containing high concentrations of interfering alkali metal ions . Sep. Sci. Technol. , 32 ( 1–4 ): 241 – 253 .[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]) Sr(II)-Ba(II) (Sr-group), by eluting with 2.0 M HNO₃ and water, respectively. The heat emitting element Sr(II) adsorbed by (DtBuCH18C6 + M)/SiO₂-P flowed into the second group along with Ba(II). Based on the results, a new process entitled SPEC (Strontium/Cesium Partitioning from HLW by Extraction Chromatography) for heat generator partitioning from a simulated highly active liquid waste utilizing two macroporous silica-based supramolecular recognition composites has been developed.     

Chromatographic partitioning of cesium by a macroporous silica‐calix[4]arene‐crown supramolecular recognition composite

A macroporous silica‐based 1,3‐[(2,4‐diethyl‐heptylethoxy)oxy]‐2,4‐crown‐6‐calix[4]arene (Calix[4]arene‐R14) supramolecular recognition polymeric composite, (Calix[4]+Oct)/SiO₂‐P, was synthesized. It was performed by impregnating and immobilizing Calix[4]arene‐R14 and n‐octanol into the pores of the macroporous SiO₂‐P particles support. n‐Octanol was used to modify Calix[4]arene‐R14 through hydrogen bonding. The effect of eight typical fission products contained in highly active liquid waste (HLW) on the adsorption of Cs(I), one of the heat generators, was investigated at 298 K by examining the effect of contact time and the HNO₃ concentration in a range of 0.3–7.0 M. (Calix[4]+Oct)/SiO₂‐P showed excellent adsorption ability and high selectivity for Cs(I) at 4.0 M HNO₃ over the tested elements. The partitioning of Cs(I) from a simulated HLW was operated by (Calix[4]+Oct)/SiO₂‐P packed column. Cs(I) was able to be effectively eluted by water and separated from the tested metals. It is demonstrated that (Calix[4]+Oct)/SiO₂‐P is promising to apply in chromatographic separation of Cs(I) from HLW. © 2010 American Institute of Chemical Engineers AIChE J, 2010     

Adsorption Behavior of Platinum Group Metals onto a Silica-based (Crea+Dodec)/SiO2-P Extraction Resin from Simulated High Level Liquid Waste

Basic properties of a silica-based macroporous N’,N’-di-n-hexyl-thiodiglycolamide (Crea) extraction resin, (Crea+Dodec)/SiO₂-P were examined. This extraction resin was synthesized by impregnating Crea and its modifier, n-Dodecyl alcohol (Dodec) into the macroporous SiO₂-P support with a mean diameter of 50 μm. Adsorption behavior of platinum group metals (PGMs) and some fission product elements from simulated high level liquid waste onto the resin was investigated by batch experiment. It was found that (Crea+Dodec)/SiO₂-P extraction resin exhibited good adsorption selectivity for PGMs over other tested elements in 0.1-5.0 M HNO₃ solution. This resin showed strong affinity to Pd(II) especially in a short contact time but almost no adsorption for rare earth elements. Adsorption behavior of PGMs in experiment could be expressed by the Langmuir monomolecular layer adsorption mode. Meanwhile, adsorption results were fitted well with the pseudo-second order model and the rate-controlling step of this adsorption process was governed by the chemisorption process. In addition, the adsorption isotherms and thermodynamic parameters of tested elements were calculated by the Langmuir, Freundlich, and van’t Hoff equations, respectively.     

Synthesis and Characterization of a New Polymer-Based Supramolecular Recognition Material and its Adsorption for Cesium

A novel macroporous polymer-based 25,27-bis(iso-propyloxy)calix[4]arene-26,28-crown-6 (BiPCalix[4]C6) supramolecular recognition material, BiPCalix[4]C6/XAD-7, was synthesized. It was performed by vacuum impregnation and immobilization of BiPCalix[4]C6 into the pores of the macroporous XAD-7 particles. The composition and structure were characterized using SEM, BET, TG-DSC, FT-IR, and XRD, respectively. The adsorption of some typical metals contained in highly active liquid waste (HLW) such as Ru(III), Mo(VI), K(I), Rb(I), Cs(I), Sr(II), Ba(II), La(III), and Y(III) onto the BiPCalix[4]C6/XAD-7 materials was investigated. The effects of the HNO₃ concentration and contact time on the adsorption of the tested metals were evaluated. It was found that at the optimum concentration of 4.0 M HNO₃, BiPCalix[4]C6/XAD-7 exhibited excellent adsorption ability and high selectivity for Cs(I) over all the other tested metals, which showed weak or almost no adsorption except Rb(I). It demonstrated that application of the polymer-based supramolecular recognition material, BiPCalix[4]C6/XAD-7, in partitioning of Cs(I) from HLW is promising.     

Adsorption of cesium and some typical elements on a novel solid-state macroporous silica-calix[4]arene material

25,27-Bis(1-hexyloxy)-calix[4]arene-26,28-crown-6 (HexylCalix[4]C6) was synthesized. A new macroporous silica-based composite material, HexylCalix[4]C6@SiO₂, was prepared through impregnation and immobilization of HexylCalix[4]C6 into the SiO₂-P particles. The adsorption of 17 species of typical metals onto HexylCalix[4]C6@SiO₂ in the range of 0.3–5.0 M HNO₃ was investigated. The material exhibited strong adsorption ability and excellent selectivity for Cs(I) over all the tested metals except for Rb(I) and Pd(II). The optimum HNO₃ concentration and the adsorption mechanism of Cs(I) onto the material were discussed. The solubility of HexylCalix[4]C6@SiO₂ in aqueous phase was evaluated by total organic carbon (TOC). The technical feasibility of application of Hexyl Calix[4]C6@SiO₂ in Cs(I) separation was confirmed.     

Adsorption behavior and radiation effects of a silica-based (Calix(4)+Dodecanol)/SiO2-P adsorbent for selective separation of Cs(I) from high level liquid waste

A macroporous silica-based (Calix[4]+Dodecanol)/SiO₂-P absorbent for separation of Cs(I) from HNO₃ solution was prepared by impregnating the 1,3-[(2,4-Diethylheptylethoxy)oxy]-2,4-crown-6-calix[4]arene and its molecule modifier 1-dodecanol into a macroporous silica/polymer composite support. To establish its application into partitioning of Cs(I) from High Level Liquid Waste (HLLW), the adsorption properties and radiation effects on the adsorbent were investigated. The adsorbent showed a relatively large distribution coefficient of Cs(I) and fast equilibrium time in simulated HLLW. Additionally, the adsorbent under the gamma-ray field was found to be able to selectively adsorb Cs(I) with similar behavior to the adsorption without irradiation up to at least 170 kGy.     

Preparation of a macroporous silica–pyridine multidentate material and its adsorption behavior for some typical elements

A new macroporous silica‐based‐polymer (SiO₂‐P) soft ligand composite material, 2,6‐bis(5,6‐di(iso‐butyl)‐1,2,4‐triazine‐3‐yl)pyridine (BDIBTP/SiO₂‐P), was synthesized by impregnation and immobilization of BDIBTP and 1‐octanol molecules into the pores of the SiO₂‐P particles. The impact of some typical alkali metal and alkaline earths Cs(I), Na(I), K(I), Rb(I), Sr(II), and Ba(II) containing in highly active liquid waste (HLW) on the adsorption of Pd(II) onto BDIBTP/SiO₂‐P was studied. It was performed by examining the effects of contact time and the HNO₃ concentration in the range of 0.3–7.0 M. BDIBTP/SiO₂‐P showed strong adsorption ability and high selectivity for Pd(II) over all the tested metals. The chromatographic partitioning of Pd(II) from a simulated HLW solution was conducted by BDIBTP/SiO₂‐P packed column. Pd(II) was effectively eluted with 0.2 M thiourea–0.1 M HNO₃. The others showed no adverse impact on separation of Pd(II). The results are beneficial to partitioning of minor actinides and Pd(II) together from HLW by BDIBTP/SiO₂‐P in the MPS process developed. © 2012 American Institute of Chemical Engineers AIChE J, 2012     

Separation of Carrier Free 90Y from 90Sr by Hollow Fiber Supported Liquid Membrane Containing Bis(2-ethylhexyl) Phosphonic Acid

The present article gives a comparative account of the efficiency of carrier-free ⁹⁰Y separation from ⁹⁰Sr by solvent extraction, flat sheet-supported liquid membrane (FSSLM) and hollow fiber-supported liquid membrane (HFSLM) methods using bis(2-ethylhexyl) phosphonic acid (PC88A) as the carrier extractant. The major focus of this work has been to develop the HFSLM method for the separation of Y(III) on a relatively large scale. The feed and receiver phase conditions were optimized by carrying out batch solvent-extraction studies. The extraction of Sr(II) by PC88A was negligible in the acidity range of 0.01–3 M HNO₃, whereas the extraction of Y(III) was significantly large at lower acidity (≤0.1 M HNO₃) with a separation factor (SF = D_Y/D_Sr) of 8.5 × 10⁴. HFSLM studies suggested selective and efficient transport of Y(III) into 3 M HNO₃ from a feed solution containing a mixture of Y(III) and Sr(II) at 0.1 M HNO₃. On the other hand, transport of Sr(II) was negligible in the receiver phase. The purity of the separated ⁹⁰Y was ascertained by paper chromatography and by half-life measurement. The radiation stability of the carrier was excellent as studied up to 1000 KGy dose.     

Synthesis of crown ether modified cation exchange polymer particles for 90Sr urinalysis

Cation exchange polymer particles have been synthesized for urinalysis to monitor levels of strontium-90 (⁹⁰Sr) exposure in humans. Two techniques were utilized in the incorporation of a Sr²⁺ selective chelating agent, di-tert-butyl-cyclohexano-18-crown-6 (DtBuCH18C6). The ion imprinting technique involved entrapment of DtBuCH18C6 during the formation of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) polymer particles. In the surface immobilization technique, adsorption of DtBuCH18C6 onto the surface of AMPS polymer particles was assisted by a molecular modifier. Ethylene glycol dimethacrylate (EGDMA) and divinylbenzene (DVB) were evaluated as cross-linking agents to provide better support for DtBuCH18C6. These polymer particles were characterized by scanning electron microscopy, dynamic light scattering, and Fourier transform infrared spectroscopy. Radiometric binding assays demonstrated that surface immobilization, in comparison to matrix imprinting, achieved greater Sr²⁺ uptake. Application of the surface immobilized particles in urinalysis was successful, attaining 86 ± 2% ⁹⁰Sr uptake at pH 9.     

Extraction of Radio-Strontium from Nitric Acid Medium Using Di-tert-Butyl Cyclohexano18-Crown-6 (DTBCH18C6) in Toluene–1-Octanol Diluent Mixture

An alternative extraction system to the SREX solvent using a diluent mixture comprising 4,4′(5′)di-tert-butylcyclohexano-18-crown-6 (DTBCH18C6) in 80% toluene–20% 1-octanol was developed and evaluated for Sr(II) extraction from pressurized heavy water reactor simulated high level waste (PHWR-SHLW). The acid uptake (5.7%) by the present solvent was significantly lower as compared to that by the SREX solvent (21%) which used 100% 1-octanol as the diluent. The extracted species conformed to the ion-pair [Sr(DTBCH18C6)(H₂O)_x]²⁺·2[(NO₃)(H₂O)_y]^?. Studies on Sr(II) extraction as a function of nitric acid concentration indicated more favorable extraction and stripping with the present solvent as compared to the SREX solvent. Loading studies with 0.025 M DTBCH18C6 in the diluent mixture, carried out using the Sr carrier, indicated a decrease in D_Sr from 3.1 with 10 ppm Sr carrier to 1.62 with 100 ppm Sr carrier. Other important physical parameters relevant for the extraction processes such as phase separation time (dispersion number), viscosity, and density were also measured. The radiation stability and reusability of the solvent was also investigated. In sharp contrast to the SREX solvent, with increasing absorbed dose the proposed solvent showed an increase in Sr extraction and an increased acid uptake.     

Synthesis of Extraction Resin Containing N,N,N′,N′-Tetraisobutyl Diglycolamide and its Application for Separation of Sr(II) from Rb(I)

Abstract

A novel Levextrel resin containing N,N,N′,N′-tetraisobutyl diglycolamide (TiBDGA) was synthesized by suspension polymerization of styrene and divinylbenzene and its performance for separation of Sr(II) from Rb(I) was investigated. The effects of crosslink degree, stirring speed, and the ratio of porogenic-agents on the resin synthesized were examined. The optimum TiBDGA resin with 40 wt.% divinylbenzene as cross linking agent and 20 wt.% of n-octanol as porogenic-agents provided excellent adsorption capacity of 22.5 mg/g. The distribution coefficient (K _d) of Sr(II) in HNO₃ media onto the resin depended heavily on the acidity in the aqueous solution. The maximum K _d for Sr(II) (7300 mL/g) was observed when the HNO₃ concentration in aqueous phase reached 2 mol/L. The difference in the Sr(II) and Rb(I) distribution coefficients of several orders of magnitude implied that ⁸⁹Sr may be separated from ⁸⁶Rb with a radionuclide purity greater than 99%. And the maximum static adsorption capacity of Sr(II) on the resin was 22.5 mg/g.     

Synthesis of a macroporous silica‐based derivative of pyridine material and its application in separation of palladium

A novel macroporous silica‐based 2,6‐bis(5,6‐dibutyl‐1,2,4‐triazine‐3‐yl)pyridine (BDBTP) material, BDBTP/SiO₂‐P, was prepared through impregnation and immobilization of BDBTP and octanol into the pores of the SiO₂‐P particles. The adsorption of 10 typical fission and nonfission elements contained in highly active liquid waste (HLW) onto BDBTP/SiO₂‐P was investigated by examining the effect of contact time and the HNO₃ concentration in the range of 0.1–5.0 M. Pd(II), a weak Lewis acid and an electron‐pair acceptor, was strongly complexed with nitrogen, a weak Lewis base and an electron‐pair donor. BDBTP/SiO₂‐P showed excellent adsorption ability and high selectivity for Pd(II) over all the tested metals. The separation of Pd(II) from a simulated HLW was performed by BDBTP/SiO₂‐P packed column. Pd(II) was effectively eluted with 0.2 M thiourea and separated from the others. It demonstrated that in HNO₃, application of the macroporous silica‐based BDBTP/SiO₂‐P material in partitioning and recovery of Pd(II) from HLW is promising. © 2010 American Institute of Chemical Engineers AIChE J, 2010     

Extraction Behavior of Some Actinides and Fission Products from Nitric Acid Medium by a New Unsymmetrical Diglycolamide

Abstract

A new unsymmetrical diglycolamide, N,N-di-2-ethylhexyl-N',N'-di-octyl-3-oxapentane-1,5-diamide, trivially known as di-ethylhexyl-di-octyl-diglycolamide (DEHDODGA) has been synthesized, and characterized by ¹H, and ¹³C nmr, mass, and IR spectroscopy. Extraction behavior of ²⁴¹Am(III), ^(152+154)Eu(III), ²³⁹Pu(III), ²³⁹Pu(IV), ²³³U(VI), ¹³⁷Cs(I), and ^(85+89)Sr(II) from nitric acid medium by a solution of DEHDODGA in n-dodecane was studied, at 298–333 K. The effect of concentrations of HNO₃ and DEHDODGA and of temperature on the distribution ratio (D _M) was studied. Extraction of Eu(III), Am(III), Pu(III), and Pu(IV) increased with increase in nitric acid concentration, and the distribution ratio of Cs(I) was insignificant. However, the distribution ratios of U(VI) and Sr(II), though not insignificant, but was quite less compared to trivalents, and Pu(IV). The D _Sr(II) increased with increase in the concentration of nitric acid, reaching a maximum at 4 M followed by decrease. The stoichiometry of Am(III) – DEHDODGA was determined by slope analysis of extraction data, and the enthalpy change accompanied by the extraction of Eu(III), Pu(III), and Am(III) was determined and reported in this article.     

Crystallographic studies on the site selectivity of Ca<Superscript>2+</Superscript>, K<Superscript>+</Superscript>, and Rb<Superscript>+</Superscript> ions within zeolite Y (Si/Al = 1.56)

The single-crystals of Ca²⁺, K⁺-exchanged zeolite Y, and Ca²⁺, Rb⁺-exchanged zeolite Y were prepared by using flow method with mixed ion-exchange solution, whose Ca(NO₃)₂:KNO₃ mole ratios were 1:1 (crystal 1) and 1:100 (crystal 2), and Ca(NO₃)₂:RbNO₃ mole ratios were 1:1 (crystal 3) and 1:100 (crystal 4), respectively, with a total concentration of 0.05 M. They were fully dehydrated by vacuum dehydration at 723 K and 1 × 10^?6 Torr for 2 days. Their crystals were determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group \(Fd \overline{3}\) m, respectively, and were refined to the final error indices R ₁/wR ₂ = 0.057/0.196, 0.073/0.223, 0.055/0.188, and 0.049/0.175 for crystals 1, 2, 3, and 4, respectively. In the structure of crystal 1 (|Ca₂₃K₂₉|[Si₁₁₇Al₇₅O₃₈₄]-FAU), 23 Ca²⁺ ions per unit cell occupy sites I, II′, and II; 29 K⁺ ions per unit cell are at sites II′, II, and III′. In the structure of crystal 2 (|Ca_18.5K₃₈|[Si₁₁₇Al₇₅O₃₈₄]-FAU), 18.5 Ca²⁺ ions per unit cell occupy sites I, I′, and II; 38 K⁺ ions are at sites I′, II, and III′. In the structure of crystal 3 (|Ca₂₇Rb₂₁|[Si₁₁₇Al₇₅O₃₈₄]-FAU), 27 Ca²⁺ ions per unit cell occupy sites I, II′, and II; 21 Rb⁺ ions per unit cell are at sites II′, II, and III. In the structure of crystal 4 (|Ca₁₈Rb₃₉|[Si₁₁₇Al₇₅O₃₈₄]-FAU), 18 Ca²⁺ ions per unit cell occupy sites I and II; 39 Rb⁺ ions per unit cell are at sites I′, II′, II, III, and III′. In the four crystals, the Ca²⁺ ion which has much smaller size and higher charge than other cations such as K⁺ and Rb⁺ energetically preferred at site I and so the first to be filled on it. Unlike Ca²⁺ ion, no K⁺ and Rb⁺ ions are found at site I, which are clearly less favorable for K⁺ and Rb⁺ ions.