Uranium is an element with a large radius and atomic mass, so its oxides are consid-ered to be of very low δ<sup>18</sup>O value at the bottom of the <sup>18</sup>O enrichment table for minera...Uranium is an element with a large radius and atomic mass, so its oxides are consid-ered to be of very low δ<sup>18</sup>O value at the bottom of the <sup>18</sup>O enrichment table for minerals.The oxygen isotope fractionation between uranium dioxide, uranium trioxide and water hasbeen calculated by Hattori & Halas using force constant and low temperature heatcapacity, which is a rare example for spectrum-heat capacity model （SHCM）. But onecould find some problems after detailed analysis of the calculated results. The force con-stants of uranium oxides are listed in table 1. Compared with the force constants展开更多
In this work,a technique was proposed to prepare UO_(2)from UO_(3)by the two processes of fluorination reaction of UO_(3)with NH_(4)HF_(2)and electrochemical reduction of UO_(2)^(2+)for the recycle uranium.The feasibi...In this work,a technique was proposed to prepare UO_(2)from UO_(3)by the two processes of fluorination reaction of UO_(3)with NH_(4)HF_(2)and electrochemical reduction of UO_(2)^(2+)for the recycle uranium.The feasibility of fluorination reaction was firstly confirmed using thermodynamic calculation;then,the products were analyzed using XRD,Raman and fluorescence to be UO_(2)F_(2).The fluorination mechanism was inferred to be UO_(3)(s)+NH_(4)HF_(2)→(NH_(4))_(3)UO_(2)F_(5)→NH_(4)(UO_(2))_(2)F_(5)→UO_(2)F_(2).The redox behavior of UO_(2)^(2+)on W electrode was investigated by cyclic voltammetry and square wave voltammetry,which indicated that UO_(2)^(2+) was reduced to UO_(2)via a two-step single electron transfer with diffusion-controlled.The diffusion coefficient of UO_(2)^(2+) was calculated to be 6.22×10^(-5)cm/s.The disproportionation reaction of UO_(2)^(+) was observed,and the relationship between the disproportionation reaction and scan rate was discussed.Moreover,the electrochemical fabrication of UO_(2) was conducted by electrolysis at-0.8 V,and the product was analyzed by XRD,SEM and EDS to be UO_(2).ICP-AES results showed that the extraction efficiency of UO_(2) could reach 98.53%.展开更多
基金National Natural Science Foundation of China and Open Laboratory of Geochemistry in Ore Deposit.
文摘Uranium is an element with a large radius and atomic mass, so its oxides are consid-ered to be of very low δ<sup>18</sup>O value at the bottom of the <sup>18</sup>O enrichment table for minerals.The oxygen isotope fractionation between uranium dioxide, uranium trioxide and water hasbeen calculated by Hattori & Halas using force constant and low temperature heatcapacity, which is a rare example for spectrum-heat capacity model （SHCM）. But onecould find some problems after detailed analysis of the calculated results. The force con-stants of uranium oxides are listed in table 1. Compared with the force constants
基金financially supported by the National Natural Science foundation of China(Nos.U2167215,22076035,21876034,11875116 and 21790373)the Fundamental Research Funds for the Central Universities(No.3072021CFJ1001)。
文摘In this work,a technique was proposed to prepare UO_(2)from UO_(3)by the two processes of fluorination reaction of UO_(3)with NH_(4)HF_(2)and electrochemical reduction of UO_(2)^(2+)for the recycle uranium.The feasibility of fluorination reaction was firstly confirmed using thermodynamic calculation;then,the products were analyzed using XRD,Raman and fluorescence to be UO_(2)F_(2).The fluorination mechanism was inferred to be UO_(3)(s)+NH_(4)HF_(2)→(NH_(4))_(3)UO_(2)F_(5)→NH_(4)(UO_(2))_(2)F_(5)→UO_(2)F_(2).The redox behavior of UO_(2)^(2+)on W electrode was investigated by cyclic voltammetry and square wave voltammetry,which indicated that UO_(2)^(2+) was reduced to UO_(2)via a two-step single electron transfer with diffusion-controlled.The diffusion coefficient of UO_(2)^(2+) was calculated to be 6.22×10^(-5)cm/s.The disproportionation reaction of UO_(2)^(+) was observed,and the relationship between the disproportionation reaction and scan rate was discussed.Moreover,the electrochemical fabrication of UO_(2) was conducted by electrolysis at-0.8 V,and the product was analyzed by XRD,SEM and EDS to be UO_(2).ICP-AES results showed that the extraction efficiency of UO_(2) could reach 98.53%.
