We studied the local structure and properties of six-fold coordinated silicon(Si[6]) in BaOSiO2-P2O5 glasses. Nuclear magnetic resonance(NMR) and Raman spectroscopy revealed the existence of sixfold coordinated silico...We studied the local structure and properties of six-fold coordinated silicon(Si[6]) in BaOSiO2-P2O5 glasses. Nuclear magnetic resonance(NMR) and Raman spectroscopy revealed the existence of sixfold coordinated silicon species and network former units(NFUs) in the BaO-SiO2-P2O5 glasses. The glass transition temperature(Tg), which was measured by differential scanning calorimetry, increased rapidly along with the increase of SiO2 from 0 to 10 mol%, then declined and finally increased again, which showed a "Z" trend along with the increase of SiO2 while the density of the glasses showed the opposite trend. When the addition of SiO2 is 16 mol%, Tg decreased to an extremely low value(807.9 K). Besides, the Vickers indentation hardness(Hv) had been significantly enhanced from 4.66 to 6.63 GPa by adding 16 mol% SiO2. Furthermore, the liquid fragility index(m) of the glasses declined slowly firstly and then increased rapidly when the amount of SiO2 is greater than 13 mol%.展开更多
A porous Me2-CA-BTP/SiO2-P adsorbent was prepared to separate MA（III） from Ln（III） in high level liquid waste （HLLW）. The adsorption behavior of Me2-CA-BTP/SiO2-P toward 241Am（III） and Ln（III） in 0.01 M HNO3...A porous Me2-CA-BTP/SiO2-P adsorbent was prepared to separate MA（III） from Ln（III） in high level liquid waste （HLLW）. The adsorption behavior of Me2-CA-BTP/SiO2-P toward 241Am（III） and Ln（III） in 0.01 M HNO3-NaNO3 solution was studied. Me2-CA-BTP/SiO2-P showed high adsorption and selectivity toward 241Am（III） over Ln（III） fission products with the separation factor （SF） reaching to 557, 2355, 1952, 1082, 214, 105, 86, 14 for Y, La, Ce, Nd, Sm, Eu, Gd and Dy respectively in 0.01 M HNO3-0.99 M NaNO3 solution. The adsorption kinetics of both Dy（III） and Eu（III） on Me2-CA-BTP/SiO2-P was studied and followed pseudo-second-order rate equation indicating chemical sorption as the rate-limiting step of the adsorption, and the adsorption isotherm of Dy（III） and Eu（III） matched better with the Langmuir isotherm than the Freundlich isotherm with the adsorption amount around 0.22 and 0.20 mmol/g respectively. Thermodynamic study revealed that the adsorption of both Dy（III） and Eu（III） on Me2-CA-BTP/SiO2-P was spontaneous and endothermic processes with a positive entropy at 298, 308, 313 K.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
The extraction chromatography–electrodeposition(EC–ED) process was proposed for the quantitative recovery of palladium from high-level liquid waste(HLLW) in this study. The process coupled the extraction chromatogra...The extraction chromatography–electrodeposition(EC–ED) process was proposed for the quantitative recovery of palladium from high-level liquid waste(HLLW) in this study. The process coupled the extraction chromatography method to obtain the decontamination of Pd(II) from HLLW with the electrochemical method to recover metallic palladium from the concentrated solution.Separation of Pd(II) from a nitric acid medium by extraction chromatography using iso Bu-BTP/SiO_2-P adsorbent and the electrochemical behavior of Pd(II) in nitric acid solution in the presence of thiourea(TU) were investigated.iso Bu-BTP/SiO_2-P exhibited a high selectivity for Pd(II)over other fission products(FPs), and Pd(II) could be desorbed by TU from loaded BTP/SiO_2-P. The adsorbent performed good stability against HNO_3 because the adsorption performance kept Pd(II) after extended contact with HNO_3 solution. The column experiment achieved the separation of Pd(II) from simulated HLLW successfully.The electrochemical behavior of Pd(II) in palladium desorption solution containing TU and nitric acid was investigated at a platinum electrode by cyclic voltammetry. A weak reduction wave at-0.4 V was due to the reduction in Pd(II) to Pd(0), and the deposition process wasirreversible. In electrowinning experiments, a maximum of92% palladium could be obtained.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 develo...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 hav- ing 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（l-aryl-lH-tetrazol-5-yl）pyridines）, into the porous silica/polymer support （SiOrP particles）. This work deals with comparison in adsorption and desorption prop- erties of Am and some FP in HNO3 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, elu- tion behaviors of U and Pd were also estimated.展开更多
基金Funded by National Natural Science Foundation of China(Nos.51772223,51372180)
文摘We studied the local structure and properties of six-fold coordinated silicon(Si[6]) in BaOSiO2-P2O5 glasses. Nuclear magnetic resonance(NMR) and Raman spectroscopy revealed the existence of sixfold coordinated silicon species and network former units(NFUs) in the BaO-SiO2-P2O5 glasses. The glass transition temperature(Tg), which was measured by differential scanning calorimetry, increased rapidly along with the increase of SiO2 from 0 to 10 mol%, then declined and finally increased again, which showed a "Z" trend along with the increase of SiO2 while the density of the glasses showed the opposite trend. When the addition of SiO2 is 16 mol%, Tg decreased to an extremely low value(807.9 K). Besides, the Vickers indentation hardness(Hv) had been significantly enhanced from 4.66 to 6.63 GPa by adding 16 mol% SiO2. Furthermore, the liquid fragility index(m) of the glasses declined slowly firstly and then increased rapidly when the amount of SiO2 is greater than 13 mol%.
基金supported by the National Natural Science of China(91126006,11305102)the Ministry of Education of Specialized Research Fund for the Doctoral Program of Higher Education (20130073110046)
文摘A porous Me2-CA-BTP/SiO2-P adsorbent was prepared to separate MA（III） from Ln（III） in high level liquid waste （HLLW）. The adsorption behavior of Me2-CA-BTP/SiO2-P toward 241Am（III） and Ln（III） in 0.01 M HNO3-NaNO3 solution was studied. Me2-CA-BTP/SiO2-P showed high adsorption and selectivity toward 241Am（III） over Ln（III） fission products with the separation factor （SF） reaching to 557, 2355, 1952, 1082, 214, 105, 86, 14 for Y, La, Ce, Nd, Sm, Eu, Gd and Dy respectively in 0.01 M HNO3-0.99 M NaNO3 solution. The adsorption kinetics of both Dy（III） and Eu（III） on Me2-CA-BTP/SiO2-P was studied and followed pseudo-second-order rate equation indicating chemical sorption as the rate-limiting step of the adsorption, and the adsorption isotherm of Dy（III） and Eu（III） matched better with the Langmuir isotherm than the Freundlich isotherm with the adsorption amount around 0.22 and 0.20 mmol/g respectively. Thermodynamic study revealed that the adsorption of both Dy（III） and Eu（III） on Me2-CA-BTP/SiO2-P was spontaneous and endothermic processes with a positive entropy at 298, 308, 313 K.
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.
基金supported by the National Natural Science Foundation of China(Nos.11305102,91126006,and 21261140335)
文摘The extraction chromatography–electrodeposition(EC–ED) process was proposed for the quantitative recovery of palladium from high-level liquid waste(HLLW) in this study. The process coupled the extraction chromatography method to obtain the decontamination of Pd(II) from HLLW with the electrochemical method to recover metallic palladium from the concentrated solution.Separation of Pd(II) from a nitric acid medium by extraction chromatography using iso Bu-BTP/SiO_2-P adsorbent and the electrochemical behavior of Pd(II) in nitric acid solution in the presence of thiourea(TU) were investigated.iso Bu-BTP/SiO_2-P exhibited a high selectivity for Pd(II)over other fission products(FPs), and Pd(II) could be desorbed by TU from loaded BTP/SiO_2-P. The adsorbent performed good stability against HNO_3 because the adsorption performance kept Pd(II) after extended contact with HNO_3 solution. The column experiment achieved the separation of Pd(II) from simulated HLLW successfully.The electrochemical behavior of Pd(II) in palladium desorption solution containing TU and nitric acid was investigated at a platinum electrode by cyclic voltammetry. A weak reduction wave at-0.4 V was due to the reduction in Pd(II) to Pd(0), and the deposition process wasirreversible. In electrowinning experiments, a maximum of92% palladium could be obtained.
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 hav- ing 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（l-aryl-lH-tetrazol-5-yl）pyridines）, into the porous silica/polymer support （SiOrP particles）. This work deals with comparison in adsorption and desorption prop- erties of Am and some FP in HNO3 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, elu- tion behaviors of U and Pd were also estimated.
