“…The promethium was harvested from the waste solutions generated by the production of 238 Pu from irradiated 237 Np targets. The concentration and initial crude separation of promethium was done using a separation column 49 in the hot cell. This had the advantage of obtaining the Pm in a manageable volume and rejecting most other fission products.…”
Section: Methodsmentioning
confidence: 99%
“… The obtained parameters ( b = -0.02053 and c = 0.000350921) and a value for = 15.42 (5 p electrons) were used to calculate the shielding constant for f electrons ( s = 0.74), based on the modified Slater model 36 . 1 σ error bars in Ln–O bond distance are computed from the covariance matrix of the non-linear minimization of the EXAFS fit 49 . Extended Data Fig.…”
Section: Extended Data Figures and Tablesmentioning
Lanthanide rare-earth metals are ubiquitous in modern technologies1–5, but we know little about chemistry of the 61st element, promethium (Pm)6, a lanthanide that is highly radioactive and inaccessible. Despite its importance7,8, Pm has been conspicuously absent from the experimental studies of lanthanides, impeding our full comprehension of the so-called lanthanide contraction phenomenon: a fundamental aspect of the periodic table that is quoted in general chemistry textbooks. Here we demonstrate a stable chelation of the 147Pm radionuclide (half-life of 2.62 years) in aqueous solution by the newly synthesized organic diglycolamide ligand. The resulting homoleptic PmIII complex is studied using synchrotron X-ray absorption spectroscopy and quantum chemical calculations to establish the coordination structure and a bond distance of promethium. These fundamental insights allow a complete structural investigation of a full set of isostructural lanthanide complexes, ultimately capturing the lanthanide contraction in solution solely on the basis of experimental observations. Our results show accelerated shortening of bonds at the beginning of the lanthanide series, which can be correlated to the separation trends shown by diglycolamides9–11. The characterization of the radioactive PmIII complex in an aqueous environment deepens our understanding of intra-lanthanide behaviour12–15 and the chemistry and separation of the f-block elements16.
“…The promethium was harvested from the waste solutions generated by the production of 238 Pu from irradiated 237 Np targets. The concentration and initial crude separation of promethium was done using a separation column 49 in the hot cell. This had the advantage of obtaining the Pm in a manageable volume and rejecting most other fission products.…”
Section: Methodsmentioning
confidence: 99%
“… The obtained parameters ( b = -0.02053 and c = 0.000350921) and a value for = 15.42 (5 p electrons) were used to calculate the shielding constant for f electrons ( s = 0.74), based on the modified Slater model 36 . 1 σ error bars in Ln–O bond distance are computed from the covariance matrix of the non-linear minimization of the EXAFS fit 49 . Extended Data Fig.…”
Section: Extended Data Figures and Tablesmentioning
Lanthanide rare-earth metals are ubiquitous in modern technologies1–5, but we know little about chemistry of the 61st element, promethium (Pm)6, a lanthanide that is highly radioactive and inaccessible. Despite its importance7,8, Pm has been conspicuously absent from the experimental studies of lanthanides, impeding our full comprehension of the so-called lanthanide contraction phenomenon: a fundamental aspect of the periodic table that is quoted in general chemistry textbooks. Here we demonstrate a stable chelation of the 147Pm radionuclide (half-life of 2.62 years) in aqueous solution by the newly synthesized organic diglycolamide ligand. The resulting homoleptic PmIII complex is studied using synchrotron X-ray absorption spectroscopy and quantum chemical calculations to establish the coordination structure and a bond distance of promethium. These fundamental insights allow a complete structural investigation of a full set of isostructural lanthanide complexes, ultimately capturing the lanthanide contraction in solution solely on the basis of experimental observations. Our results show accelerated shortening of bonds at the beginning of the lanthanide series, which can be correlated to the separation trends shown by diglycolamides9–11. The characterization of the radioactive PmIII complex in an aqueous environment deepens our understanding of intra-lanthanide behaviour12–15 and the chemistry and separation of the f-block elements16.
“…The energy consumption model constructed by Stella software can obtain a simulation estimation model of energy consumption by inputting conditions such as GDP, population, and the proportion of output value of each industry. This model can effectively overcome errors caused by missing data [22].…”
This study aimed to respond to the national “carbon peak” mid-and long-term policy plan, comprehensively promote energy conservation and emission reduction, and accurately manage and predict carbon emissions. Firstly, the proposed method analyzes the Yangtze River Economic Belt as well as its “carbon peak” and carbon emissions. Secondly, a support vector regression (SVR) machine prediction model is proposed for the carbon emission information prediction of the Yangtze River Economic Zone. This experiment uses a long short-term memory neural network (LSTM) to train the model and realize the experiment’s prediction of carbon emissions. Finally, this study obtained the fitting results of the prediction model and the training model, as well as the prediction results of the prediction model. Information indicators such as the scale of industry investment, labor efficiency output, and carbon emission intensity that affect carbon emissions in the “Yangtze River Economic Belt” basin can be used to accurately predict the carbon emissions information under this model. Therefore, the experiment shows that the SVR model for solving complex nonlinear problems can achieve a relatively excellent prediction effect under the training of LSTM. The deep learning model adopted herein realized the accurate prediction of carbon emission information in the Yangtze River Economic Zone and expanded the application space of deep learning. It provides a reference for the model in related fields of carbon emission information prediction, which has certain reference significance.
“…Current industrialized separations for actinide elements rely on solid sorbent materials and solvent extraction techniques. − Anion-exchange resins functionalized with quaternary ammonium or sulfonic acid functional groups can selectively separate actinides, whereas chromatographic resins containing the diglycolamide ligand TODGA have demonstrated impressive separations for a range of actinide and lanthanide elements. − While the formation of actinide metalates is implicated in these processes, the precise mechanisms are not wholly understood. Impregnated polymer resins containing acidic alkylphosphorus extractants have also been developed that show significant selectivity for actinide cations generated in the production of 252 Cf and 238 Pu, among other isotopes. , However, challenges exist regarding resin stability, scalability, and disposal of the resulting contaminated waste material.…”
Section: Introductionmentioning
confidence: 99%
“…Impregnated polymer resins containing acidic alkylphosphorus extractants have also been developed that show significant selectivity for actinide cations generated in the production of 252 Cf and 238 Pu, among other isotopes. 23 , 27 However, challenges exist regarding resin stability, scalability, and disposal of the resulting contaminated waste material.…”
Improving actinide separations is key to reducing barriers to medical and industrial actinide isotope production and to addressing the challenges associated with the reprocessing of spent nuclear fuel. Here, we report the first example of a supramolecular anion recognition process that can achieve this goal. We have designed a preorganized triamidoarene receptor that induces quantitative precipitation of the early actinides Th(IV), Np(IV), and Pu(IV) from industrially relevant conditions through the formation of self-assembled hydrogen-bonded capsules. Selectivity over the later An(III) elements is shown through modulation of the nitric acid concentration, and no precipitation of actinyl or transition-metal ions occurs. The Np, Pu, and Am precipitates were characterized structurally by single-crystal X-ray diffraction and reveal shape specificity of the internal hydrogen-bonding array for the encapsulated hexanitratometalates. This work complements ion-exchange resins for 5f-element separations and illustrates the significant potential of supramolecular separation methods that target anionic actinide species.
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