In order to separate Zr(IV) and Hf(IV) in acidic solution,several kinds of silica-based macroporous adsorbents were synthesized.Their adsorption selectivity for Zr(IV) and Hf(IV) in HCl solution was investigated,and t...In order to separate Zr(IV) and Hf(IV) in acidic solution,several kinds of silica-based macroporous adsorbents were synthesized.Their adsorption selectivity for Zr(IV) and Hf(IV) in HCl solution was investigated,and the TODGA adsorbent for the two elements had the largest adsorption difference.The effects of acid type,HCl concentration,and temperature on the adsorption behavior of Zr(IV) and Hf(IV) onto the TODGA adsorbent were conducted by batch experiments.It was found that H+exhibited a quite strong influence on adsorption capacity of Zr(IV) and Hf(IV).Isotherm fitting showed that the Langmuir model agrees well with the experimental data.The thermodynamic parameters indicate that the adsorption processes for both elements are endothermic reactions.The TODGA adsorbent had the higher adsorption selectivity for Zr(IV) over Hf(IV) and could be promising for their mutual separation.展开更多
Basic properties of a silica-based octyl(phenyl)-N,N-diisobutylcarbamoyl-methylphosphine oxide (CMPO) extraction resin (CMPO/SiO2-P) was investigated.Adsorption behavior for some rare earth elements (RE) which are con...Basic properties of a silica-based octyl(phenyl)-N,N-diisobutylcarbamoyl-methylphosphine oxide (CMPO) extraction resin (CMPO/SiO2-P) was investigated.Adsorption behavior for some rare earth elements (RE) which are constituents of high level liquid waste (HLLW) and the long-term stability of the extraction resin in nitric acid solution were examined.The CMPO extraction resin was significantly stable in 3 mol·L?1 HNO3 solution at 50oC.Furthermore,the RE(III) were efficiently separated from non-adsorptive fission product (FP) elements such as Sr(II) in a column experiment using a highly nitric acid solution.The separation behaviors of the elements are considered to result from the difference in their adsorption and elution selectivity based on the complex formation with CMPO.There was no strong dependency of RE(III) separation efficiency on feed solution flow rate.Only from the perspectives of the acid-resistant behavior of CMPO extraction resin and the elution kinetics for the metal ions with the extraction resin,the CMPO extraction resin can be used in the modified MAREC process for HLLW partitioning.展开更多
A functional microcapsule was prepared by encapsulating the fine crystalline ammonium tungstophosphate(AWP) in calcium alginate polymer(CaALG).The characterization of AWP-CaALG microcapsule was examined by SEM and EPM...A functional microcapsule was prepared by encapsulating the fine crystalline ammonium tungstophosphate(AWP) in calcium alginate polymer(CaALG).The characterization of AWP-CaALG microcapsule was examined by SEM and EPMA.The adsorption behavior of Cs(I),Rb(I),Sr(II),Pd(II),Ru(III),Rh(III),La(III),Ce(III),Dy(III) and Zr(IV) was investigated by the batch method.The batch experiments were carried out by varying the shaking times,HNO 3 concentration,and initial concentration of metal ions.Relatively large K d values above 10 5 cm 3 /g for Cs(I) were obtained in the range of 0.1-5 M HNO 3,resulting in a separation factor of Cs/Rb exceeding 10 2.In contrast,the K d values of Sr(II),Pd(II),Ru(III),La(III),Dy(III),Ce(III) and Zr(IV) were considerably lower than 50 cm 3 /g.The K d value of Cs(I) decreased in the order of the coexisting ions,H + > Na + >> NH 4 +,and a linear relationship with a slop of about 1 was obtained between log K d and log [NH 4 + ]([NH 4 + ] > 0.01 M).The adsorption of Cs(I) was found to be controlled by chemisorption mechanism,and followed a Langmuir-type adsorption equation.A high uptake percentage of 99.4% for Cs(I) was obtained by using the dissolved solutions of spent fuel from FBR-JOYO(JAEA).展开更多
To separate MA(Am,Cm) and some fission product elements(FPs) such as Tc,Pd,Cs and Sr from high level liquid waste(HLLW) systematically,we have been studying an advanced aqueous partitioning process,which uses selectiv...To separate MA(Am,Cm) and some fission product elements(FPs) such as Tc,Pd,Cs and Sr from high level liquid waste(HLLW) systematically,we have been studying an advanced aqueous partitioning process,which uses selective adsorption as the separation method.For this process,we prepared several novel adsorbents which were immobilized in a porous silica/polymer composite support(SiO 2-P).Adsorption and separation behavior of various elements was studied experimentally in detail.Small scale separation tests using simulated HLLW solutions were carried out.Pd(II) was strongly adsorbed by the AR-01 anion exchanger and effectively eluted off by using thiourea.Successful separation of Pd(II) from simulated HLLW was achieved.Tc(VII) also exhibited strong adsorption on AR-01 and could be eluted off by using U(IV) as a reductive eluent.Am(III) presented significantly high adsorbability and selectivity onto R-BTP/SiO 2-P adsorbents over various FPs including Ln(III).The R-BTP adsorbents were fairly stable in 3 M HNO 3,but instable against-irradiation-3M HNO 3.An advanced partitioning process consisting of three separation columns for the target elements separation from HLLW was proposed and the obtained experiment results indicated that the proposed process is essentially feasible.展开更多
In this study,the electrochemical behavior of Pd(II)in nitric acid media was investigated using various electrochemical techniques.By analyzing the cyclic voltammogram of Pd(II)recorded at Pt electrode,a series of ele...In this study,the electrochemical behavior of Pd(II)in nitric acid media was investigated using various electrochemical techniques.By analyzing the cyclic voltammogram of Pd(II)recorded at Pt electrode,a series of electrochemical reactions associated with palladium were recognized,indicating that Pd(II)undergoes a single step two-electrons irreversible process.Electroreduction reaction of Pd(II)and auto-catalytic reactions of nitrous acid are supposed to play a leading role in low and high concentrations of nitric acid,respectively.Stirring could facilitate the reduction of Pd(II)in relatively low nitric acid concentration(3 mol/L).The value of charge transfer coefficient was determined to be 0.18 for the measurements at 298 K.The diffusion coefficient of Pd(II)increased from 1.89×10 8cm2/s at 288 K to 4.23×10 8cm2/s at 318 K,and the activation energy was calculated to be 21.5 kJ/mol.In electrowinning experiments,SEM images of palladium obtained by electrolysis reveal the dendrite growth in all cases,which is uniform all over the entire surface of Pt electrode.The recovery ratios of Pd at different nitric acid concentrations are high,and the faradic efficiency of electrolysis decreases with increasing the nitric acid concentration.When stirring was introduced during electrolysis,the electrodeposition rate of Pd increased substantially.展开更多
In order to directly separate trivalent minor actinides(MA:Am,Cm) from fission products(FP) containing rare earths(RE) in high level radioactive liquid waste(HLLW),the authors have challenged to develop a simplified M...In order to directly separate trivalent minor actinides(MA:Am,Cm) from fission products(FP) containing rare earths(RE) in high level radioactive liquid waste(HLLW),the authors have challenged to develop a simplified MA separation process by extraction chromatography using a single column.Attention has been paid to a new type of nitrogen-donor ligands,R-BTP(2,6-bis(5,6-dialkyl-1,2,4-triazin-3-yl) pyridine,R:alkyl group) as an extractant because it shows high extraction selectivity for Am(Ⅲ) over RE(Ⅲ).It is known that the R-BTP ligands show different properties such as adsorbability and stability by having different alkyl groups.Therefore,some novel adsorbents were prepared by impregnating different types of R-BTP ligands(isohexyl-,isoheptyl-and cyheptyl-BTP) and a similar ligand to the R-BTP,ATP(2,6-bis(1-aryl-1H-tetrazol-5-yl)pyridines),into the porous silica/polymer support(SiO2-P particles).This work deals with comparison in adsorption and desorption properties of Am and some FP in HNO 3 solution onto such R-BTP type adsorbents,as well as chemical and radiolytic stability of the adsorbents.Then the possibility of a single-column separation of MA from main FP was pursued by evaluating the results of column experiments using the most promising adsorbent(isohexyl-BTP/SiO2-P) under temperature control.In addition,elution behaviors of U and Pd were also estimated.展开更多
Palladium(II)and chloride ions tend to form complexes in aqueous solution.Both theoretical and experimental(by UV spectrum)results indicate that there are four complexes formed in aqueous solution containing 3 mol/L h...Palladium(II)and chloride ions tend to form complexes in aqueous solution.Both theoretical and experimental(by UV spectrum)results indicate that there are four complexes formed in aqueous solution containing 3 mol/L hydrochloric acid and 20mmol/L PdCl2.This work evaluates the kinetics of electrochemical deposition of palladium on a Platinum electrode.For this purpose,palladium electrodeposition was investigated by means of cyclic voltammetry(CV),potentiostatic current-time transients(CTTs)and Tafel curve.By CTTs curves,the regions corresponding to the charge transfer control,mixed control and diffusion control were identified.In the diffusion control region,palladium electrodeposition mechanism was characterized as progressive nucleation with three-dimensional(3D)growth under diffusion control;as for the mixed control region,an adsorption(IAds),ion transfer(IIT),and nucleation and growth(ING)model were proposed to analyze the current-time transients quantitatively,which could separate the IAds,IIT and ING perfectly.展开更多
Development of highly functional cesium selective adsorbents for the decontamination of high-activity-level water(HALW) from the Fukushima NPP-1 accident is very urgent. In order to selectively adsorb the radioactive ...Development of highly functional cesium selective adsorbents for the decontamination of high-activity-level water(HALW) from the Fukushima NPP-1 accident is very urgent. In order to selectively adsorb the radioactive cesium, three kinds of novel porous silica gels loaded with insoluble ferrocyanides(SLFC) were prepared using a successive impregnation/precipitation method. Based on the results of previous research, the SLFC composites have relatively large uptake ratio above 95%, distribution coefficients(Kd) above 103 cm3/g, and excellent adsorption kinetics even in seawater. The solidification results also indicate that zeolites have an excellent Cs immobilization characteristic, gas-trapping and self-sintering abilities, and low leachability. We chose three kinds of SLFC composites to achieve the optimization of solidification by mixing with nine kinds of additives at high temperatures(up to 1200 °C). The Cs contents in the three composites were estimated to be below 30% of the initial contents and decreased with the three stages at calcination temperatures ranging from 25 to 1200 °C. By contrast, the Cs immobilization ratio was markedly lowered by mixing with additives: of those, allophane had the best immobilization result. By increasing the additive ratio to 50 wt%, the Cs immobilization ratio became almost 100% and no volatilization of Cs was detected even after calcination at 1200 °C. This result indicates that calcination of the mixture of SLFC composites after adsorbing Cs+ ions and specific additives under appropriate ratio is effective for stable solidification.展开更多
Founded in 1935, the Institute of Mathematical Statistics (IMS) is an international professional and scholastic society devoted to the development, dissemination, and application of statistics and probability.IMS Chin...Founded in 1935, the Institute of Mathematical Statistics (IMS) is an international professional and scholastic society devoted to the development, dissemination, and application of statistics and probability.IMS China, established in 2007, promotes the participation of Chinese scholars in activities of the Institute of Mathematical Statistics.展开更多
Separation of trivalent minor actinides(MA(ⅡI): Am(ⅡI), Cm(ⅡI)) from fission products(FP) in high-level liquid waste(HLLW) is an important task in advanced nuclear-fuel reprocessing systems. For this purpose, an ad...Separation of trivalent minor actinides(MA(ⅡI): Am(ⅡI), Cm(ⅡI)) from fission products(FP) in high-level liquid waste(HLLW) is an important task in advanced nuclear-fuel reprocessing systems. For this purpose, an advanced aqueous partitioning process based on extraction chromatography method was studied. Because R-BTP extractants(R-BTP: 2,6-bis(5,6-dialkyl-1,2,4-triazin-3-yl)pyridine, R = alkyl group) exhibit high selectivity for MA(ⅡI) over trivalent rare-earth elements(RE(ⅡI)), a novel adsorbent isoHex-BTP/SiO2-P was prepared by impregnating isoHex-BTP extractant into the macroporous SiO2-P support with a mean diameter of 60 μm. The stability of isoHex-BTP/SiO2-P against nitric acid and γ-irradiation was investigated. It was found that isoHex-BTP/SiO2-P adsorbent shows good adsorption affinity to Dy(ⅡI). The hydrolytic and radiolytic stability of isoHex-BTP/SiO2-P adsorbent in 0.01 mol/L HNO3 was fairly promising. However, the adsorption amount Q of Dy(ⅡI) decreased dramatically in 3 mol/L HNO3 with the increase of the absorbed dose and became nearly zero at the absorbed dose over 46 kGy. These results suggest that with the synergetic effect of radiation and acidic hydrolysis, the adsorbent instantly loses its efficacy.展开更多
基金Supported by National Natural Science Foundation of China(No.91126006,and 91226111)
文摘In order to separate Zr(IV) and Hf(IV) in acidic solution,several kinds of silica-based macroporous adsorbents were synthesized.Their adsorption selectivity for Zr(IV) and Hf(IV) in HCl solution was investigated,and the TODGA adsorbent for the two elements had the largest adsorption difference.The effects of acid type,HCl concentration,and temperature on the adsorption behavior of Zr(IV) and Hf(IV) onto the TODGA adsorbent were conducted by batch experiments.It was found that H+exhibited a quite strong influence on adsorption capacity of Zr(IV) and Hf(IV).Isotherm fitting showed that the Langmuir model agrees well with the experimental data.The thermodynamic parameters indicate that the adsorption processes for both elements are endothermic reactions.The TODGA adsorbent had the higher adsorption selectivity for Zr(IV) over Hf(IV) and could be promising for their mutual separation.
文摘Basic properties of a silica-based octyl(phenyl)-N,N-diisobutylcarbamoyl-methylphosphine oxide (CMPO) extraction resin (CMPO/SiO2-P) was investigated.Adsorption behavior for some rare earth elements (RE) which are constituents of high level liquid waste (HLLW) and the long-term stability of the extraction resin in nitric acid solution were examined.The CMPO extraction resin was significantly stable in 3 mol·L?1 HNO3 solution at 50oC.Furthermore,the RE(III) were efficiently separated from non-adsorptive fission product (FP) elements such as Sr(II) in a column experiment using a highly nitric acid solution.The separation behaviors of the elements are considered to result from the difference in their adsorption and elution selectivity based on the complex formation with CMPO.There was no strong dependency of RE(III) separation efficiency on feed solution flow rate.Only from the perspectives of the acid-resistant behavior of CMPO extraction resin and the elution kinetics for the metal ions with the extraction resin,the CMPO extraction resin can be used in the modified MAREC process for HLLW partitioning.
文摘A functional microcapsule was prepared by encapsulating the fine crystalline ammonium tungstophosphate(AWP) in calcium alginate polymer(CaALG).The characterization of AWP-CaALG microcapsule was examined by SEM and EPMA.The adsorption behavior of Cs(I),Rb(I),Sr(II),Pd(II),Ru(III),Rh(III),La(III),Ce(III),Dy(III) and Zr(IV) was investigated by the batch method.The batch experiments were carried out by varying the shaking times,HNO 3 concentration,and initial concentration of metal ions.Relatively large K d values above 10 5 cm 3 /g for Cs(I) were obtained in the range of 0.1-5 M HNO 3,resulting in a separation factor of Cs/Rb exceeding 10 2.In contrast,the K d values of Sr(II),Pd(II),Ru(III),La(III),Dy(III),Ce(III) and Zr(IV) were considerably lower than 50 cm 3 /g.The K d value of Cs(I) decreased in the order of the coexisting ions,H + > Na + >> NH 4 +,and a linear relationship with a slop of about 1 was obtained between log K d and log [NH 4 + ]([NH 4 + ] > 0.01 M).The adsorption of Cs(I) was found to be controlled by chemisorption mechanism,and followed a Langmuir-type adsorption equation.A high uptake percentage of 99.4% for Cs(I) was obtained by using the dissolved solutions of spent fuel from FBR-JOYO(JAEA).
基金supported by the National Natural Science Foundation of China (91026019,91126006)
文摘To separate MA(Am,Cm) and some fission product elements(FPs) such as Tc,Pd,Cs and Sr from high level liquid waste(HLLW) systematically,we have been studying an advanced aqueous partitioning process,which uses selective adsorption as the separation method.For this process,we prepared several novel adsorbents which were immobilized in a porous silica/polymer composite support(SiO 2-P).Adsorption and separation behavior of various elements was studied experimentally in detail.Small scale separation tests using simulated HLLW solutions were carried out.Pd(II) was strongly adsorbed by the AR-01 anion exchanger and effectively eluted off by using thiourea.Successful separation of Pd(II) from simulated HLLW was achieved.Tc(VII) also exhibited strong adsorption on AR-01 and could be eluted off by using U(IV) as a reductive eluent.Am(III) presented significantly high adsorbability and selectivity onto R-BTP/SiO 2-P adsorbents over various FPs including Ln(III).The R-BTP adsorbents were fairly stable in 3 M HNO 3,but instable against-irradiation-3M HNO 3.An advanced partitioning process consisting of three separation columns for the target elements separation from HLLW was proposed and the obtained experiment results indicated that the proposed process is essentially feasible.
基金supported by the National Natural Science Foundation of China(91026019,91126006)
文摘In this study,the electrochemical behavior of Pd(II)in nitric acid media was investigated using various electrochemical techniques.By analyzing the cyclic voltammogram of Pd(II)recorded at Pt electrode,a series of electrochemical reactions associated with palladium were recognized,indicating that Pd(II)undergoes a single step two-electrons irreversible process.Electroreduction reaction of Pd(II)and auto-catalytic reactions of nitrous acid are supposed to play a leading role in low and high concentrations of nitric acid,respectively.Stirring could facilitate the reduction of Pd(II)in relatively low nitric acid concentration(3 mol/L).The value of charge transfer coefficient was determined to be 0.18 for the measurements at 298 K.The diffusion coefficient of Pd(II)increased from 1.89×10 8cm2/s at 288 K to 4.23×10 8cm2/s at 318 K,and the activation energy was calculated to be 21.5 kJ/mol.In electrowinning experiments,SEM images of palladium obtained by electrolysis reveal the dendrite growth in all cases,which is uniform all over the entire surface of Pt electrode.The recovery ratios of Pd at different nitric acid concentrations are high,and the faradic efficiency of electrolysis decreases with increasing the nitric acid concentration.When stirring was introduced during electrolysis,the electrodeposition rate of Pd increased substantially.
文摘In order to directly separate trivalent minor actinides(MA:Am,Cm) from fission products(FP) containing rare earths(RE) in high level radioactive liquid waste(HLLW),the authors have challenged to develop a simplified MA separation process by extraction chromatography using a single column.Attention has been paid to a new type of nitrogen-donor ligands,R-BTP(2,6-bis(5,6-dialkyl-1,2,4-triazin-3-yl) pyridine,R:alkyl group) as an extractant because it shows high extraction selectivity for Am(Ⅲ) over RE(Ⅲ).It is known that the R-BTP ligands show different properties such as adsorbability and stability by having different alkyl groups.Therefore,some novel adsorbents were prepared by impregnating different types of R-BTP ligands(isohexyl-,isoheptyl-and cyheptyl-BTP) and a similar ligand to the R-BTP,ATP(2,6-bis(1-aryl-1H-tetrazol-5-yl)pyridines),into the porous silica/polymer support(SiO2-P particles).This work deals with comparison in adsorption and desorption properties of Am and some FP in HNO 3 solution onto such R-BTP type adsorbents,as well as chemical and radiolytic stability of the adsorbents.Then the possibility of a single-column separation of MA from main FP was pursued by evaluating the results of column experiments using the most promising adsorbent(isohexyl-BTP/SiO2-P) under temperature control.In addition,elution behaviors of U and Pd were also estimated.
基金supported by the National Natural Science Foundation of China(91026019,91126006)
文摘Palladium(II)and chloride ions tend to form complexes in aqueous solution.Both theoretical and experimental(by UV spectrum)results indicate that there are four complexes formed in aqueous solution containing 3 mol/L hydrochloric acid and 20mmol/L PdCl2.This work evaluates the kinetics of electrochemical deposition of palladium on a Platinum electrode.For this purpose,palladium electrodeposition was investigated by means of cyclic voltammetry(CV),potentiostatic current-time transients(CTTs)and Tafel curve.By CTTs curves,the regions corresponding to the charge transfer control,mixed control and diffusion control were identified.In the diffusion control region,palladium electrodeposition mechanism was characterized as progressive nucleation with three-dimensional(3D)growth under diffusion control;as for the mixed control region,an adsorption(IAds),ion transfer(IIT),and nucleation and growth(ING)model were proposed to analyze the current-time transients quantitatively,which could separate the IAds,IIT and ING perfectly.
基金supported by JST Strategic Japanese-Chinese Research Cooperative Program 2013
文摘Development of highly functional cesium selective adsorbents for the decontamination of high-activity-level water(HALW) from the Fukushima NPP-1 accident is very urgent. In order to selectively adsorb the radioactive cesium, three kinds of novel porous silica gels loaded with insoluble ferrocyanides(SLFC) were prepared using a successive impregnation/precipitation method. Based on the results of previous research, the SLFC composites have relatively large uptake ratio above 95%, distribution coefficients(Kd) above 103 cm3/g, and excellent adsorption kinetics even in seawater. The solidification results also indicate that zeolites have an excellent Cs immobilization characteristic, gas-trapping and self-sintering abilities, and low leachability. We chose three kinds of SLFC composites to achieve the optimization of solidification by mixing with nine kinds of additives at high temperatures(up to 1200 °C). The Cs contents in the three composites were estimated to be below 30% of the initial contents and decreased with the three stages at calcination temperatures ranging from 25 to 1200 °C. By contrast, the Cs immobilization ratio was markedly lowered by mixing with additives: of those, allophane had the best immobilization result. By increasing the additive ratio to 50 wt%, the Cs immobilization ratio became almost 100% and no volatilization of Cs was detected even after calcination at 1200 °C. This result indicates that calcination of the mixture of SLFC composites after adsorbing Cs+ ions and specific additives under appropriate ratio is effective for stable solidification.
文摘Founded in 1935, the Institute of Mathematical Statistics (IMS) is an international professional and scholastic society devoted to the development, dissemination, and application of statistics and probability.IMS China, established in 2007, promotes the participation of Chinese scholars in activities of the Institute of Mathematical Statistics.
基金supported by the National Natural Science Foundation of China(91126006,11305102)the Research Fund for the Doctoral Program of Higher Education of China(20130073110046)
文摘Separation of trivalent minor actinides(MA(ⅡI): Am(ⅡI), Cm(ⅡI)) from fission products(FP) in high-level liquid waste(HLLW) is an important task in advanced nuclear-fuel reprocessing systems. For this purpose, an advanced aqueous partitioning process based on extraction chromatography method was studied. Because R-BTP extractants(R-BTP: 2,6-bis(5,6-dialkyl-1,2,4-triazin-3-yl)pyridine, R = alkyl group) exhibit high selectivity for MA(ⅡI) over trivalent rare-earth elements(RE(ⅡI)), a novel adsorbent isoHex-BTP/SiO2-P was prepared by impregnating isoHex-BTP extractant into the macroporous SiO2-P support with a mean diameter of 60 μm. The stability of isoHex-BTP/SiO2-P against nitric acid and γ-irradiation was investigated. It was found that isoHex-BTP/SiO2-P adsorbent shows good adsorption affinity to Dy(ⅡI). The hydrolytic and radiolytic stability of isoHex-BTP/SiO2-P adsorbent in 0.01 mol/L HNO3 was fairly promising. However, the adsorption amount Q of Dy(ⅡI) decreased dramatically in 3 mol/L HNO3 with the increase of the absorbed dose and became nearly zero at the absorbed dose over 46 kGy. These results suggest that with the synergetic effect of radiation and acidic hydrolysis, the adsorbent instantly loses its efficacy.