The sequestration of^(99)Tc represents one of the most challenging tasks in nuclear waste decontamination In the event of a radioactive waste leak,^(99)TcO_(4)^(-)(a main form of^(99)Tc)would spread into the groundwa ...The sequestration of^(99)Tc represents one of the most challenging tasks in nuclear waste decontamination In the event of a radioactive waste leak,^(99)TcO_(4)^(-)(a main form of^(99)Tc)would spread into the groundwa ter,a scenario difficult to address with conventional anion exchange materials like resin and inorganic cationic sorbents.Herein,we present a nickel(II)metal-organic framework(MOF),TNU-143,featuring3D four-fold interpenetrated networks.TNU-143 exhibits efficient ReO_(4)^(-)(a nonradioactive analogue o^(99)TcO_(4)^(–))removal with fast anion exchange kinetics(<1 min),high sorption capacity(844 mg/g for ReO_(4)^(-))and outstanding selectivity over common anions.More importantly,TNU-143 shows superior stability in alkaline solution and can remove 91.6%ReO_(4)^(-)from simulated alkaline high-level waste(HLW)stream with solid-liquid ratio of 40 g/L.The uptake mechanism is elucidated by the single-crystal structure o TNU-143(Re),showing that ReO_(4)^(-)anions are firmly coordinated to nickel cation to result in a 2D lay ered structures.Density functional theory(DFT)calculations confirm the transformation from TNU-143 to TNU-143(Re)is a thermodynamically favorable process.This work presents a new approach to the removal of Re O_(4)^(-)/^(99)TcO_(4)^(-)from alkaline nulcear fuel using MOF sorbents.展开更多
A novel CVD process for the preparation of ultrafine rhenium powders was investigated using ammonium perrhenate as starting materials. In the process, volatile rhenium oxides, such as ReO4 and Re2O7, were vaporized un...A novel CVD process for the preparation of ultrafine rhenium powders was investigated using ammonium perrhenate as starting materials. In the process, volatile rhenium oxides, such as ReO4 and Re2O7, were vaporized under a controlled oxidizing atmosphere via the pyrolysis of ammonium perrhenate, and carried into reduction zone by carrier gas, and there reduced into rhenium powders by hydrogen gas. Thermodynamic calculations indicated that Re207 could be prevented from further decomposition through controlling the oxygen partial pressure higher than 10 1.248 Pa in the pyrolysis of ammonium perrhenate. This result was further validated via DSC-TGA analysis of ammonium perrhenate. The typical rhenium powders prepared by the CVD method proposed show irregular polyhedron morphology with particle size in the range of 100-800 nm and a Ds0 of 308 nm. The specific surface area and oxygen content were measured to be 4.37 m^2/g and 0.45%, respectively.展开更多
The complex of sodium perrhenate with ester derivative of calix[4]arene having the stoichiometric formula [NaL]Reo4.H2O, was prepared. The X-ray structure analysis revealed that the sodium ion is coordinated to four e...The complex of sodium perrhenate with ester derivative of calix[4]arene having the stoichiometric formula [NaL]Reo4.H2O, was prepared. The X-ray structure analysis revealed that the sodium ion is coordinated to four ether and four carbonyl oxygen atoms giving a coordination number of eight with a tetragonal antiprism configUration. The complex cation [NaL]+ and anion ReO4 are linked by electrostatic attraction.展开更多
Ionic covalent organic framework(COF)materials with high specific surface areas and well-defined pore structures are desired for many applications yet seldom reported.Herein,we report a cationic pyridinium salt-based ...Ionic covalent organic framework(COF)materials with high specific surface areas and well-defined pore structures are desired for many applications yet seldom reported.Herein,we report a cationic pyridinium salt-based COF(PS-COF-1)with a Brunauer-Emmett-Teller(BET)surface area of 2703 m^(2) g^(-1),state-ofthe-art for an ionic COF.Aided by its ordered pore structure,chemical stability,and radiation resistance,PS-COF-1 showed exceptional adsorption properties toward aqueous ReO_(4)^(-)(1262 mg g^(-1))and ^(99)TcO_(4)^(-).Its adsorption performance surpassed its corresponding amorphous analogue.Importantly,PS-COF-1 exhibited fast adsorption kinetics,high adsorption capacities,and selectivity for ^(99)TcO_(4)^(-)and ReO_(4)^(-)at high ionic strengths,leading to the successful removal of ^(99)TcO_(4)^(-)under conditions relevant to low-activity waste streams at US legacy Hanford nuclear sites.In addition,PS-COF-1 can rapidly decontaminate ReO_(4)^(-)/^(99)TcO_(4)^(-)polluted potable water(~10 ppb)to drinking water level(0 ppb,part per billion)within 10 min.Density functional theory(DFT)calculations revealed PS-COF-1 has a strong affinity for ReO_(4)^(-)and ^(99)TcO_(4)^(-),thereby favoring adsorption of these low charge density anions over other common anions(e.g.,Cl^(-),NO_(3)^(-),SO_(4)^(2-),CO_(3)^(2-)).Our work demonstrates a novel cationic COF sorbent for selective radionuclide capture and legacy nuclear waste management.展开更多
^(99)Tc is a long-lived radionuclide present in large amounts as TcO_(4)^(-)-anion in used nuclear fuel.Its removal from the waste stream is highly desirable because of its interference capability with actinide separa...^(99)Tc is a long-lived radionuclide present in large amounts as TcO_(4)^(-)-anion in used nuclear fuel.Its removal from the waste stream is highly desirable because of its interference capability with actinide separation and its volatile nature during the nuclear waste vitrification process.Despite the progress achieved in the past few years,the design of anion-exchange materials with optimized Tc uptake property and improved stability under the extreme condition is still a research goal beneficial for reducing the volume of secondary radioactive solid waste generated during the waste partitioning process.However,their design philosophy remains elusive,with challenges coming from charge repulsion,steric hindrance,and insufficient reactive sites within the materials.Herein,we present a design philosophy of cationic polymer network materials for TcO_(4)^(-)separation by systematic precursor screening and structure prediction.This affords an optimized material,SCU-CPN-2(SCU=Soochow University),with extremely high positive charge density while maintaining high radiation resistance.SCU-CPN-2 exhibits a record high adsorption capacity1,467 mg/g towards the surrogate ReO_(4)^(-)compared to all anion-exchange materials reported up to date.In addition to ultrafast adsorption kinetics,SCU-CPN-2 has remarkable selectivity over nitrate and sulfate,and facile recyclability.展开更多
基金supported by National Natural Science Foundation of China(No.22171210)Research Project of Tianjin Education Commission(No.2023KJ182)Tianjin Research Innovation Project for Postgraduate Students(No.2022BKY200)。
文摘The sequestration of^(99)Tc represents one of the most challenging tasks in nuclear waste decontamination In the event of a radioactive waste leak,^(99)TcO_(4)^(-)(a main form of^(99)Tc)would spread into the groundwa ter,a scenario difficult to address with conventional anion exchange materials like resin and inorganic cationic sorbents.Herein,we present a nickel(II)metal-organic framework(MOF),TNU-143,featuring3D four-fold interpenetrated networks.TNU-143 exhibits efficient ReO_(4)^(-)(a nonradioactive analogue o^(99)TcO_(4)^(–))removal with fast anion exchange kinetics(<1 min),high sorption capacity(844 mg/g for ReO_(4)^(-))and outstanding selectivity over common anions.More importantly,TNU-143 shows superior stability in alkaline solution and can remove 91.6%ReO_(4)^(-)from simulated alkaline high-level waste(HLW)stream with solid-liquid ratio of 40 g/L.The uptake mechanism is elucidated by the single-crystal structure o TNU-143(Re),showing that ReO_(4)^(-)anions are firmly coordinated to nickel cation to result in a 2D lay ered structures.Density functional theory(DFT)calculations confirm the transformation from TNU-143 to TNU-143(Re)is a thermodynamically favorable process.This work presents a new approach to the removal of Re O_(4)^(-)/^(99)TcO_(4)^(-)from alkaline nulcear fuel using MOF sorbents.
文摘A novel CVD process for the preparation of ultrafine rhenium powders was investigated using ammonium perrhenate as starting materials. In the process, volatile rhenium oxides, such as ReO4 and Re2O7, were vaporized under a controlled oxidizing atmosphere via the pyrolysis of ammonium perrhenate, and carried into reduction zone by carrier gas, and there reduced into rhenium powders by hydrogen gas. Thermodynamic calculations indicated that Re207 could be prevented from further decomposition through controlling the oxygen partial pressure higher than 10 1.248 Pa in the pyrolysis of ammonium perrhenate. This result was further validated via DSC-TGA analysis of ammonium perrhenate. The typical rhenium powders prepared by the CVD method proposed show irregular polyhedron morphology with particle size in the range of 100-800 nm and a Ds0 of 308 nm. The specific surface area and oxygen content were measured to be 4.37 m^2/g and 0.45%, respectively.
文摘The complex of sodium perrhenate with ester derivative of calix[4]arene having the stoichiometric formula [NaL]Reo4.H2O, was prepared. The X-ray structure analysis revealed that the sodium ion is coordinated to four ether and four carbonyl oxygen atoms giving a coordination number of eight with a tetragonal antiprism configUration. The complex cation [NaL]+ and anion ReO4 are linked by electrostatic attraction.
基金supported by the National Natural Science Foundation of China(U2167218 and 22006036)the National Key Research and Development Program of China(2017YFA0207002 and 2018YFC1900105)+2 种基金the Science Challenge Project(TZ2016004)the Beijing Outstanding Young Scientist Program(H.Y.and X.W.)the Robert A.Welch Foundation(B-0027)(S.M.)。
文摘Ionic covalent organic framework(COF)materials with high specific surface areas and well-defined pore structures are desired for many applications yet seldom reported.Herein,we report a cationic pyridinium salt-based COF(PS-COF-1)with a Brunauer-Emmett-Teller(BET)surface area of 2703 m^(2) g^(-1),state-ofthe-art for an ionic COF.Aided by its ordered pore structure,chemical stability,and radiation resistance,PS-COF-1 showed exceptional adsorption properties toward aqueous ReO_(4)^(-)(1262 mg g^(-1))and ^(99)TcO_(4)^(-).Its adsorption performance surpassed its corresponding amorphous analogue.Importantly,PS-COF-1 exhibited fast adsorption kinetics,high adsorption capacities,and selectivity for ^(99)TcO_(4)^(-)and ReO_(4)^(-)at high ionic strengths,leading to the successful removal of ^(99)TcO_(4)^(-)under conditions relevant to low-activity waste streams at US legacy Hanford nuclear sites.In addition,PS-COF-1 can rapidly decontaminate ReO_(4)^(-)/^(99)TcO_(4)^(-)polluted potable water(~10 ppb)to drinking water level(0 ppb,part per billion)within 10 min.Density functional theory(DFT)calculations revealed PS-COF-1 has a strong affinity for ReO_(4)^(-)and ^(99)TcO_(4)^(-),thereby favoring adsorption of these low charge density anions over other common anions(e.g.,Cl^(-),NO_(3)^(-),SO_(4)^(2-),CO_(3)^(2-)).Our work demonstrates a novel cationic COF sorbent for selective radionuclide capture and legacy nuclear waste management.
基金supported by the National Natural Science Foundation of China(21790374,21825601,21806117,21906114,22006108)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)the National Key R&D Program of China(2018YFB1900203)。
文摘^(99)Tc is a long-lived radionuclide present in large amounts as TcO_(4)^(-)-anion in used nuclear fuel.Its removal from the waste stream is highly desirable because of its interference capability with actinide separation and its volatile nature during the nuclear waste vitrification process.Despite the progress achieved in the past few years,the design of anion-exchange materials with optimized Tc uptake property and improved stability under the extreme condition is still a research goal beneficial for reducing the volume of secondary radioactive solid waste generated during the waste partitioning process.However,their design philosophy remains elusive,with challenges coming from charge repulsion,steric hindrance,and insufficient reactive sites within the materials.Herein,we present a design philosophy of cationic polymer network materials for TcO_(4)^(-)separation by systematic precursor screening and structure prediction.This affords an optimized material,SCU-CPN-2(SCU=Soochow University),with extremely high positive charge density while maintaining high radiation resistance.SCU-CPN-2 exhibits a record high adsorption capacity1,467 mg/g towards the surrogate ReO_(4)^(-)compared to all anion-exchange materials reported up to date.In addition to ultrafast adsorption kinetics,SCU-CPN-2 has remarkable selectivity over nitrate and sulfate,and facile recyclability.
