| 1. |
- Airaksinen, Anu J., et al.
(author)
-
Massive Online Open Course „Essential Radiochemistry for Society“
- 2023
-
In: Chemicke Listy. - 1213-7103 .- 0009-2770. ; 117:11, s. 708-713
-
Journal article (peer-reviewed)abstract
- The massive open online course "Essential radio-chemistry for society" represents a modern form of education. Due to its attractive design, varied content and inter-active nature, it has the potential to appeal to various inter-est groups. Thematically, the course is divided into five weeks: Radiochemistry for the environment, health, indus-try, nuclear energy and society. In addition to radiochem-istry and nuclear chemistry, which are the basis of the course, direct connections can be found to biology, phys-ics, ecology, art and culture. The course is comprehensive; a participant can study only selected chapters or the entire course independently. Recommendations and tips for ef-fectively using the course in classes have been compiled for teachers and lecturers.
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Aneheim, Emma, 1982, et al.
(author)
-
A TBP/BTBP-based GANEX Separation Process. Part 1: Feasibility
- 2010
-
In: Solvent Extraction and Ion Exchange. - : Informa UK Limited. - 0736-6299 .- 1532-2262. ; 28:4, s. 437-458
-
Journal article (peer-reviewed)abstract
- A GANEX (Group ActiNide EXtraction) separation system for transmutation has been developed. In this separation process the actinides should be extracted as a group from the lanthanides and the fission and corrosion/activation products. This can be achieved by combining BTBP (bis-triazine-bipyridine) with TBP (tri-butyl phosphate) in cyclohexanone. From 4M nitric acid this organic system extracts the actinides (log(DAm) = 2.19, log(DPu) = 2.31, log(DU) = 1.03, log(DNp) = 0.53) and also separates them from the lanthanides (log(DLa) = -2.0, log(DCe) = -1.72, log(DNd) = -1.05, log(DSm) = -0.18, log(DEu) = -0.02). One problem encountered is that some of the fission and corrosion products are also extracted. The new system however still looks feasible.
|
|
| 5. |
|
|
| 6. |
|
|
| 7. |
- Chagnes, A., et al.
(author)
-
WEEE recycling: Research, development, and policies
- 2016
-
Book (other academic/artistic)abstract
- WEEE Recycling: Research, Development, and Policies covers policies, research, development, and challenges in recycling of waste electrical and electronic equipment (WEEE). The book introduces WEEE management and then covers the environmental, economic, and societal applications of e-waste recycling, focusing on the technical challenges to designing efficient and sustainable recycling processes-including physical separation, pyrometallurgical, and hydrometallurgical processes. The development of processes for recovering strategic and critical metals from urban mining is a priority for many countries, especially those having few available ores mining. Describes the two metallurgical processes-hydro- and pyro-metallurgy-and their application in recycling of metals Provides a life cycle analysis in the WEEE recycling of metals Outlines how to determine economic parameters in the recycling of waste metals Discusses the socio economic and environmental implication of metal recycling.
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
|
|
| 11. |
- Ekberg, Christian, 1967, et al.
(author)
-
Fuel fabrication and reprocessing issues: the ASGARD project
- 2020
-
In: EPJ NUCLEAR SCIENCES & TECHNOLOGIES. - : EDP Sciences. - 2491-9292. ; 6
-
Research review (peer-reviewed)abstract
- The ASGARD project (2012-2016) was designed to tackle the challenge the multi-dimensional questions dealing with the recyclability of novel nuclear fuels. These dimensions are: the scientific achievements, investigating how to increase the industrial applicability of the fabrication of these novel fuels, the bridging of the often separate physics and chemical communities in connection with nuclear fuel cycles and finally to create an ambitious education and training platform. This will be offered to younger scientists and will include a broadening of their experience by international exchange with relevant facilities. At the end of the project 27 papers in peer reviewed journals were published and it is expected that the real number will be the double. The training and integration success was evidenced by the fruitful implementation of the Travel Fund as well as the unique schools, e.g. practical and theoretical handling of plutonium.
|
|
| 12. |
|
|
| 13. |
- Ekberg, Christian, 1967, et al.
(author)
-
Thermodynamics of Dissolution for Bis(triazine)-Bipyridine-Class Ligands in Different Diluents and Its Reflection on Extraction
- 2010
-
In: Journal of Chemical & Engineering Data. - : American Chemical Society (ACS). - 0021-9568 .- 1520-5134. ; 55:11, s. 5133-5137
-
Journal article (peer-reviewed)abstract
- Hydrochemical separation processes are one of the methods used for the treatment of spent nuclear fuel. Solvent extraction is also used in many other non-nuclear applications like the mining industry. In the nuclear case, hydrochemical separation processes are already employed in the world today for the recovery of uranium and plutonium. The method is however also considered for future separation systems for use in combination with the transmutation of the minor actinides. In a hydrochemical separation process the two phases are the pregnant (usually) aqueous feed and the organic phase comprising a diluent together with one or more extractants. One such class of extractants developed for partitioning and transmutation purposes is the bis(triazine)-bipyridine-type (BTBP) molecules. When assessing the feasibility and loading properties of such an extraction system, the solubility of the ligands is of the outmost importance. The understanding of whether the dissolution is enthalpically or entropically driven will also help the understanding of the differences in extraction observed between various diluents and temperatures. In this paper the enthalpy and entropy of dissolution of the BTBP-class ligands have been determined for different diluents. It has also been shown that it is possible to predict the extraction behavior of these molecules in the selected diluent once the solubility is known.
|
|
| 14. |
- Felix, J., et al.
(author)
-
Increasing the sustainability of LCD recycling
- 2012
-
In: Joint International Conference and Exhibition on Electronics Goes Green 2012+, ECG 2012, Berlin, 9 - 12 September 2012. - 9783839604397 ; , s. Art. no. 6360490-
-
Conference paper (peer-reviewed)abstract
- The present paper reports on selected findings made within the Swedish joint R&D project 'Sustainable Recycling of Flat Panel Displays'. The results presented are specifically related to i) Process for indium recovery from LCD glass; ii) Recovery and re-use of optical components; and iii) Sustainability rating of different recycling scenarios involving mainly large-scale shredding and manual dismantling. Process parameters for high yield recovery of indium from LCD glass were investigated and results indicate that the process can be employed for large-scale sustainable recovery. Re-use of optical components from discarded LCD screens in high-end applications, particularly in LED fittings, was evaluated and found to improve energy efficiency of the fitting as well as economical and ecological sustainability of the recycling scenario. Life cycle impact was evaluated for different recycling scenarios developed for LCD screens.
|
|
| 15. |
- Felix, J., et al.
(author)
-
P-61: Recycling and re-use of LCD components and materials
- 2010
-
In: Digest of Technical Papers - SID International Symposium. - : Wiley. - 2168-0159 .- 0097-966X. ; 41, s. 1469-1472
-
Conference paper (peer-reviewed)abstract
- Methods for extracting components and materials from waste liquid crystal displays have been developed. The methods enable the components to be extracted with their key properties preserved, thus qualifying them for re-use both in LCD and other applications. Novel applications for re-use of recycled LCD components have been developed in which the LCD components contribute with a substantial customer benefit.
|
|
| 16. |
- Fermvik, Anna, 1978, et al.
(author)
-
Influence of dose rate on the radiolytic stability of a BTPB solvent for actinide(III)/lanthanide(III) separation
- 2009
-
In: Radiochimica Acta. - : Walter de Gruyter GmbH. - 0033-8230. ; 97:6, s. 1-6
-
Journal article (peer-reviewed)abstract
- The recently developed ligand MF2-BTBP dissolved in cyclohexanone is a promising solvent for the group separation of trivalent actinides(III) from the lantha-nides(III). Its high stability against nitric acid has been demonstrated recently. Since the solvent is also exposed to a continuously high radiation level in the counter current process, the radiolytic stability of the solvent was examined in this study. Irradiation experiments were carried out up to an absorbed dose of 100 kGy and the effect of the dose rate was investigated. The extraction behaviour for An(III)/Ln(III) separation was studied after radiolysis for evaluation. It was found that during high dose rate irradia-tion the extraction efficiency for both Am(III) and Eu(III) decreased significantly with increasing absorbed dose, whereas during the low dose rate irradiation the extraction efficiencies remained more or less at the same level.
|
|
| 17. |
|
|
| 18. |
- Fermvik, Anna, 1978, et al.
(author)
-
Radiolysis of solvents containing C5-BTBP: identification of degradation products and their dependence on absorbed dose and dose rate
- 2009
-
In: Dalton Transactions. - 1477-9226 .- 1477-9234. ; 32, s. 6421-6430
-
Journal article (peer-reviewed)abstract
- Solvents intended for the separation of trivalent actinides from trivalent lanthanides in spent nuclear fuel have been irradiated with gamma-radiation. The solvents initially contained 0.005 M C5-BTBP dissolved in either hexanol or cyclohexanone and they were exposed to doses up to 20 kGy. Identification of degradation products was done using atmospheric pressure chemical ionization-mass spectrometry (APCI-MS). Structures were suggested for a number of degradation products and the relative intensity of the peaks in the MS spectra was estimated. It was clear that the content of the original molecule, C5-BTBP, decreased with dose, while the content of the various degradation products increased. It was also shown that both the choice of diluent and the dose rate (Gy/h) affect the amount of degradation products formed. A degradation scheme was proposed for the radiolytic degradation of C5-BTBP.
|
|
| 19. |
|
|
| 20. |
- Gergoric, Marino, 1989, et al.
(author)
-
Characterization and Leaching of Neodymium Magnet Waste and Solvent Extraction of the Rare-Earth Elements Using TODGA
- 2017
-
In: Journal of Sustainable Metallurgy. - : Springer Science and Business Media LLC. - 2199-3831 .- 2199-3823. ; 3:3, s. 638-645
-
Journal article (peer-reviewed)abstract
- The rare-earth elements (REEs) are considered as some of the most critical elements in the EU and the USA today. E-scrap, such as end-of-life neodymium magnets, could be a viable secondary source for the recovery of these elements. Neodymium magnets (NdFeB) consist of considerable amounts of Nd, Dy, Pr, and some other REEs, depending on the specific application. Apart from REEs, neodymium magnets are made up of around 60% iron, which can pose a challenge in their recycling. For example, iron can be dissolved along with other elements during leaching or co-extracted during solvent extraction. In this work, extraction of REEs with TODGA (tetraoctyl-diglycolamide) from a real leachate, obtained by neodymium magnet powder dissolution in nitric acid, was studied. The goal was to selectively extract the REEs from other elements in the solution. TODGA was used as the extracting agent due to its selective extraction properties for REEs and other f-block elements. The influence of the diluent on the overall extraction and the selectivity of the extraction was studied in order to determine application feasibility of future processes. To this end, experiments using Solvent 70 (hydrocarbons C11-C14, ae 0.5 wt% aromatics), hexane, toluene, cyclohexanone and 1-octanol as the diluents were performed. TODGA has shown good selectivity between REEs and other elements in solution under almost all conditions, reaching the highest distribution ratios of REEs in the aliphatic diluents, while the distribution ratios of other non-REEs reach a mere value of 0.1. An exception was cyclohexanone, which has the ability to extract small amounts of ions itself. The highest separation factors between Dy and the light REEs (Nd and Pr) were observed with a 0.01 M solution of TODGA in Solvent 70. REEs, as group, were extracted with 0.1 M solutions of TODGA in all diluents except for cyclohexanone, which led to extraction of Al and B at amounts greater than 10%. Stripping with over 98% efficiency was achieved using MQ water in one step.
|
|
| 21. |
- Gergoric, Marino, 1989, et al.
(author)
-
Leaching and recovery of rare-earth elements from neodymium magnet waste using organic acids
- 2018
-
In: Metals. - : MDPI AG. - 2075-4701. ; 8:9
-
Journal article (peer-reviewed)abstract
- Over the last decade, rare-earth elements (REEs) have become critical in the European Union (EU) in terms of supply risk, and they remain critical to this day. End-of-life electronic scrap (e-scrap) recycling can provide a partial solution to the supply of REEs in the EU. One such product is end-of-life neodymium (NdFeB) magnets, which can be a feasible source of Nd, Dy, and Pr. REEs are normally leached out of NdFeB magnet waste using strong mineral acids, which can have an adverse impact on the environment in case of accidental release. Organic acids can be a solution to this problem due to easier handling, degradability, and less poisonous gas evolution during leaching. However, the literature on leaching NdFeB magnets waste with organic acids is very scarce and poorly investigated. This paper investigates the recovery of Nd, Pr, and Dy from NdFeB magnets waste powder using leaching and solvent extraction. The goal was to determine potential selectivity between the recovery of REEs and other impurities in the material. Citric acid and acetic acid were used as leaching agents, while di-(2-ethylhexyl) phosphoric acid (D2EHPA) was used for preliminary solvent extraction tests. The highest leaching efficiencies were achieved with 1 mol/L citric acid (where almost 100% of the REEs were leached after 24 h) and 1 mol/L acetic acid (where >95% of the REEs were leached). Fe and Co—two major impurities—were co-leached into the solution, and no leaching selectivity was achieved between the impurities and the REEs. The solvent extraction experiments with D2EHPA in Solvent 70 on 1 mol/L leachates of both acetic acid and citric acid showed much higher affinity for Nd than Fe, with better extraction properties observed in acetic acid leachate. The results showed that acetic acid and citric acid are feasible for the recovery of REEs out of NdFeB waste under certain conditions.
|
|
| 22. |
- Gergoric, Marino, et al.
(author)
-
Recovery of Rare-Earth Elements from Neodymium Magnet Waste Using Glycolic, Maleic, and Ascorbic Acids Followed by Solvent Extraction
- 2019
-
In: Journal of Sustainable Metallurgy. - : Springer Science and Business Media LLC. - 2199-3831 .- 2199-3823. ; 5:1, s. 85-96
-
Journal article (peer-reviewed)abstract
- Rare-earth elements (REEs) play a key role in modern societies as their usage keeps increasing in new technologies and green energy sources. However, they are also considered the most critical raw materials in the EU and the USA in terms of supply. There is an increased global interest in the recycling of REEs from end-of-life products and industrial waste. Some REEs, such as Nd, Pr, and Dy, can be recovered from neodymium magnets. These magnets are of special interest since they are present in various technological wastes, such as hard disk drives, electric generators for wind turbines, electric motors, etc. Separation of REEs from other magnet components, such as Fe, which is the main part of the alloy, and further reprocessing of REEs, is the main goal of this work. In this work, neodymium magnet powder was successfully leached using the fully combustible organic lixiviants maleic, glycolic, and ascorbic acids, in order to potentially decrease the usage of strong mineral acids in the hydrometallurgical recovery of REEs. Subsequently, the REEs were selectively extracted from these leachates. For this separation step, several phosphate extractants (TBP, D2EHPA, Cyanex 272, and 923) were investigated, alongside TODGA, which follows the CHON principle and is fully combustible, with no ash or acidic gases being produced. The influences of various diluents (1-octanol, cyclohexanone, hexane, pentane, and dodecane) on the extraction were also studied since the diluents can play an important role in the extraction process and increase selectivity between the extraction of REEs and other impurities. Leaching was shown to be more efficient with maleic and glycolic acids than with ascorbic acid, even at room temperature. Values above 95% were reached for REEs with 1 M concentration and 1/80 solid/liquid ratio. For ascorbic acid, heating the leaching system to 70 A degrees C allowed similar values to be reached. D2EHPA has shown good extraction properties for the recovery of REEs from both glycolic and maleic leachate, mostly with nonpolar diluents such as pentane and hexane, without extracting transition metals (distribution ratios under 0.1). TODGA also showed good extraction of REEs and selectivity between elements, but only in the maleic leachate. As expected, the increasing concentration of the D2EHPA led to the increased distribution ratios. Thus, glycolic, maleic, and ascorbic organic acids, which have not been used before for leaching of neodymium magnet waste, showed good potential for the recovery of REEs from neodymium magnets and for the further development of large-scale recovery processes for REEs.
|
|
| 23. |
- Gergoric, Marino, 1989, et al.
(author)
-
Separation of Heavy Rare-Earth Elements from Light Rare-Earth Elements Via Solvent Extraction from a Neodymium Magnet Leachate and the Effects of Diluents
- 2017
-
In: Journal of Sustainable Metallurgy. - : Springer Science and Business Media LLC. - 2199-3831 .- 2199-3823. ; 3:3, s. 601-610
-
Journal article (peer-reviewed)abstract
- In recent decades, rare-earth elements (REEs) have seen a considerable increase in usage in modern technologies and the so-called green energy sources. The REEs are currently regarded to be among the most critical elements by the European Union (EU) and the United States (USA). Large investments are made in the research of recycling of the REEs from end-of-life products and E-scrap. One potential source for recycling of larger amounts of neodymium and dysprosium are end-of-life neodymium magnets. In this work, the selective extraction of REEs from a sulfuric media leachate (containing Nd, Dy, Pr, Gd, Co, and B) obtained by selective roasting of NdFeB waste and leaching was investigated. The extracting agent D2EHPA (di-(2-ethylhexyl) phosphoric acid) diluted in Solvent 70, hexane, octane, cyclohexanone, chloroform, 1-octanol, and toluene was used for the investigation of the effects of using different diluents on the extraction of REEs and the separation between the light and the heavy REEs. The concentrations of D2EHPA in the used diluents were 0.3, 0.6, 0.9, and 1.2 M. The highest separation factors between the heavy and the light REEs were achieved using 0.3 M D2EHPA in hexane, while no B or Co extraction was measurable. The REEs were completely extracted as a group using 0.9 M or 1.2 M D2EHPA in either octane or hexane, also with no B or Co extraction. The aliphatic nonpolar diluents showed better properties than the aromatic and polar ones. The complete stripping of REEs from the loaded organic phases was proven to be efficient using hydrochloric acid at concentrations of 2 M or higher.
|
|
| 24. |
- Gonzalez Fonseca, Luis Guillermo, 1993, et al.
(author)
-
Application of SPS in the fabrication of UN and (U,Th)N pellets from microspheres
- 2020
-
In: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 536
-
Journal article (peer-reviewed)abstract
- In this study, the process involved in the fabrication of a potential accident tolerant fuel is described. Homogeneous uranium nitride microspheres doped with different thorium content were successfully manufactured using an internal gelation process followed by carbothermic reduction, and nitridation. Elemental analysis of the materials showed low carbon and oxygen content, the two major impurities found in the products of carbothermic reduction. Uranium nitride microspheres were pressed and sintered using spark plasma sintering (SPS) to produce pellets with variable density. Final density can be tailored by choosing the sintering temperature, pressure and time. Density values of 77–98% of theoretical density (%TD) were found. As expected, higher temperatures and pressures resulted in a denser material. Furthermore, a direct correlation between the onset sintering temperature and thorium content in the materials was observed. The change of onset temperature has been related to an increment in the activation energy for self-diffusion due to the substitution of uranium atoms by thorium in the crystal structure.
|
|
| 25. |
- Gonzalez Fonseca, Luis Guillermo, 1993, et al.
(author)
-
Oxidation and hydrolysis of thorium doped uranium nitride fuel for use in LWR
- 2021
-
In: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115. ; 555
-
Journal article (peer-reviewed)abstract
- Uranium nitride is being investigated as a replacement for UO2 as it shows enhanced thermal properties and seems to be a promising accident tolerant fuel (ATF) candidate. The main drawback of UN fuel is its innate low oxidation resistance in air/water environments. This becomes a challenge for the implementation of UN fuel in water-cooled reactors. The effect of thorium doping in the stability of uranium nitride microspheres and pellets sintered by spark plasma sintering (SPS) was investigated in oxidizing environments using thermogravimetric analysis and autoclave testing. It was found that during oxidation in air the density had a noticeable effect, increasing the reaction onset temperatures in pellets with higher densities. In addition, thorium doping improved the oxidation resistance of pellets in air by increasing the maximal reaction rate temperature by approximately 50 K. However, this effect was almost nonexistent in highly porous doped microspheres. The interaction with water at 373 K showed that pellets manufactured using SPS can survive unchanged for at least six hours in boiling water, which is an improvement to cold-pressed pellets. At 473 and 573 K, the pellets were oxidized and disintegration into an oxide powder was observed. Thorium-doped uranium nitride pellets did not present any improvement with respect to the oxidation resistance of UN in water at these temperatures.
|
|
| 26. |
- Gonzalez Fonseca, Luis Guillermo, 1993, et al.
(author)
-
Preparation of Chromium doped uranium nitride via Sol-Gel and Carbothermic reduction
- 2023
-
In: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115. ; 574
-
Journal article (peer-reviewed)abstract
- Uranium nitride (UN) has been proposed as an accident tolerant fuel due to its enhanced thermal properties compared to the standard UO2. However, due to its low oxidation resistance, its implementation in water cooled reactors has not been allowed. A method to improve the corrosion resistance involves doping with oxide scale forming elements such as aluminum or chromium. In this work, UN microspheres were produced by an internal gelation method followed by carbothermic reduction and nitridation. Chromium was added as dopant in the solution to produce a homogenous mixture with uranium. The ternary phase (U2CrN3) was observed for the first time in Cr-doped UN microspheres produced via sol-gel and carbothermic reduction. Materials with and without the ternary phase were produced, and a mechanism of reaction was proposed. Chromium precipitations were also observed on the surface of the microspheres produced, indicating low solubility of Cr compounds in the UN matrix. ICP-MS and XRF measurements showed that Cr content is reduced after heating treatments, probably due to evaporation. Additionally, these results showed that Cr in the ternary phase is completely soluble in aqua regia, unlike the Cr in the material without the ternary phase.
|
|
| 27. |
- Herzfeld Olsson, Petra, 1966-, et al.
(author)
-
Concluding remarks
- 2016
-
In: National Effects of the Implementation of EU Directives on Labour Migration from Thrid Countries. - : Wolters Kluwer. - 9789041162571 ; , s. 217-241, s. 209-212
-
Book chapter (other academic/artistic)
|
|
| 28. |
- Negrin, Maddalena, et al.
(author)
-
A MOOC in Nuclear- and Radio-Chemistry: from the design to the feedback
- 2023
-
In: Journal of Radioanalytical and Nuclear Chemistry. - : Springer Science and Business Media LLC. - 0236-5731 .- 1588-2780. ; 332:5, s. 1549-1555
-
Journal article (peer-reviewed)abstract
- Recently, the loss of expertise in the nuclear- and radio-chemistry (NRC) is becoming an issue of concern, because of few engaging curricula and career prospects. To counteract this trend, the Massive Open Online Course “Essential Radiochemistry for Society” has been developed with the intent of letting young students in scientific matters discover all the benefits of NRC to society and improving their awareness of these disciplines. The MOOC development process as well as the feedbacks collected in the first MOOC editions are analyzed by highlighting strong points and weakness of the followed strategy.
|
|
| 29. |
|
|
| 30. |
- Nordlund, Anders, 1964, et al.
(author)
-
Building a comprehensive nuclear education in Sweden
- 2013
-
In: Conference on Nuclear Training and Education 2013, CONTE 2013: An International Forum for Discussion of Issues Facing Nuclear Energy Training and Education. - 9781627480130 ; , s. 40-
-
Conference paper (peer-reviewed)
|
|
| 31. |
- Purchase, Diane, et al.
(author)
-
Global occurrence, chemical properties, and ecological impacts of e-wastes (IUPAC Technical Report)
- 2020
-
In: Pure and Applied Chemistry. - : Walter de Gruyter GmbH. - 1365-3075 .- 0033-4545. ; 92:11, s. 1733-1767
-
Journal article (peer-reviewed)abstract
- The waste stream of obsolete electronic equipment grows exponentially, creating a worldwide pollution and resource problem. Electrical and electronic waste (e-waste) comprises a heterogeneous mix of glass, plastics (including flame retardants and other additives), metals (including rare Earth elements), and metalloids. The e-waste issue is complex and multi-faceted. In examining the different aspects of e-waste, informal recycling in developing countries has been identified as a primary concern, due to widespread illegal shipments; weak environmental, as well as health and safety, regulations; lack of technology; and inadequate waste treatment structure. For example, Nigeria, Ghana, India, Pakistan, and China have all been identified as hotspots for the disposal of e-waste. This article presents a critical examination on the chemical nature of e-waste and the resulting environmental impacts on, for example, microbial biodiversity, flora, and fauna in e-waste recycling sites around the world. It highlights the different types of risk assessment approaches required when evaluating the ecological impact of e-waste. Additionally, it presents examples of chemistry playing a role in potential solutions. The information presented here will be informative to relevant stakeholders seeking to devise integrated management strategies to tackle this global environmental concern.
|
|
| 32. |
|
|
| 33. |
|
|
| 34. |
- Retegan Vollmer, Teodora, 1979, et al.
(author)
-
Electrospray Ionization Mass Spectrometry Investigation of BTBP - Lanthanide(III) and Actinide(III) Complexes
- 2009
-
In: Solvent Extraction and Ion Exchange. - : Informa UK Limited. - 0736-6299 .- 1532-2262. ; 27:5-6, s. 663-682
-
Journal article (peer-reviewed)abstract
- In the framework of nuclear waste reprocessing, the separation processes of minor actinides from fission products are developed using liquid-liquid extraction. To gain an understanding of the mechanism involved in the extraction process, a complex formation of actinides and lanthanides with BTBPs (6,6'-bis(5,6-dialkyl-1,2,4-triazin-3-yl)-2,2'-bipyridines) was characterized using the Electrospray Ionization Mass Spectrometry (ESI-MS) technique. This study was carried out to compare the influence of diluents and side groups of the extractants on complex formation. Three different diluents, nitrobenzene, octanol and cyclohexanone, and two extractants, C5-BTBP and CyMe4-BTBP, were selected for this experiment. It was found that the change of the diluent and of the substituent on the BTBP moiety does not modify the stoichiometry of the complexes which is L2M(NO3)3. It is proposed that one nitrate is directly coordinated to the metal ion, the two other anions probably remaining in the outer coordination sphere. The difference observed in extracting properties is probably due to the solvation of the complexes by the diluent. The noncovalent force that holds complexes together are likely to be largely governed by electrostatic interactions even if the hydrophobic exterior of the complexes plays an important role in the complexation/extraction mechanism. The study of the stability of the ions in the gas phase shows that the C5-BTBP ligand has a labile hydrogen atom, which is a fragility point of C5-BTBP.
|
|
| 35. |
- Retegan Vollmer, Teodora, 1979, et al.
(author)
-
Extraction of actinides with different 6,60-bis(5,6-dialkyl-[1,2,4]-triazin-3-yl)[2,20]-bipyridines (BTBPs)
- 2007
-
In: SOLVENT EXTRACTION AND ION EXCHANGE. - : Informa UK Limited. - 0736-6299 .- 1532-2262. ; 25:4, s. 417-431
-
Journal article (peer-reviewed)abstract
- The extraction of Am(III), Th(IV), Np(V), and U(VI) from nitric acid by 6,6′‐bis(5,6‐dialkyl‐[1,2,4]‐triazin‐3‐yl)‐[2,2′]‐bipyridines (C2‐, C4‐, C5‐, and CyMe4‐BTBP) was studied. Since only americium and neptunium extraction was dependent on the BTBP concentration, computational chemistry was used to explain this behavior. It has been shown that the coordination of the metal played an important role in forming an extractable complex into the organic phase, thus making it possible to extract pentavalent and trivalent elements from tetravalent and hexavalent elements. This is very important, especially because it shows other possible utilizations of a group of molecules meant to separate the actinides from the lanthanides. In addition, the level of extraction at very low or no BTBP concentration was explained by coordination chemistry.
|
|
| 36. |
- Retegan Vollmer, Teodora, 1979, et al.
(author)
-
Foreword
- 2018
-
In: Journal of Radioanalytical and Nuclear Chemistry. - : Springer Science and Business Media LLC. - 0236-5731 .- 1588-2780. ; 316:2, s. 761-763
-
Journal article (other academic/artistic)
|
|
| 37. |
- Retegan Vollmer, Teodora, 1979, et al.
(author)
-
Human capital needs - Teaching, training and coordination for nuclear fuel cycle
- 2013
-
In: International Nuclear Fuel Cycle Conference, GLOBAL 2013: Nuclear Energy at a Crossroads. ; 2, s. 1621-1624
-
Conference paper (peer-reviewed)abstract
- Human capital is the accumulation of competencies, knowledge, social and creativity skills and personality attributes, which are necessary to perform work so as to produce economic value. In the frame of the nuclear fuel cycle, this is of paramount importance that the right human capital exists and in Europe this is fostered by a series of integrated or directed projects. The teaching, training and coordination will be discussed in the frame of University curricula with examples from several programs, like e.g. the Master of Nuclear Engineering at Chalmers University, Sweden and two FP7 EURATOM Projects: CINCH and ASGARD. The integration of the university curricula in the market needs but also the anchoring in the research and future fuel cycles will be also discussed, with examples from the ASGARD project.
|
|
| 38. |
- Retegan Vollmer, Teodora, 1979
(author)
-
Investigations of Solvent Systems Based on bis-triazine-bipyridine (BTBP) - class Ligands for the Separation of Actinides from Lanthanides
- 2009
-
Doctoral thesis (other academic/artistic)abstract
- Shortages of fossil fuel and other political movements contributed to the nuclear energy “renaissance”.Nuclear energy, however, is not free of challenges, one of them being nuclear waste management. The “once-through” cycle, where the nuclear fuel is used once in the reactor, cooled and finnaly disposed for about 100 000 years is currently used in most of the world. Reprocessing is another alternative, by making new fuel from separated uranium, MOX (Mixed Oxyde fuel). However, the storage time remains the same.An alternative to the storage time and radiotoxicity is partitioning and transmutation (P&T) concept. Transmutation is defined as the transformation of one radionuclide into another by changing its nuclear structure. The partitioning is the process of separation nuclides from the rest of the waste and involves a separation process which utilize an organic solvent containing one or several molecules and a diluent for extraction purposes. Among the last extractant families developed in Europe, used for partitioning, the 6,6’-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-benzo[1,2,4]triazin-3-yl)-[2,2’]bipyridine (BTBP) is the most promising molecule for an eventual industrial application. The present work focuses on several aspects insufficiently studied before in relation to a BTBP based extraction system. These aspects include: the importance of the diluents regarding both the extraction capabilities of the formed system with different metals, the role of the diluents in complex formation , the importance of the side groups added to the molecule to facilitate dissolution, easing the phase transfer and thus enhancing the extraction capabilities and also the role of the side groups in complex formation.
|
|
| 39. |
- Retegan Vollmer, Teodora, 1979, et al.
(author)
-
Synthesis and Screening of t-Bu-CyMe4-BTBP, and Comparison with CyMe4-BTBP
- 2014
-
In: Solvent Extraction and Ion Exchange. - : Informa UK Limited. - 0736-6299 .- 1532-2262. ; 32:7, s. 720-736
-
Journal article (peer-reviewed)abstract
- The effect of adding a t-butyl group to the core molecule of CyMe4-BTBP, with the aim of improving solubility in organic diluents, has been studied with regard to the extraction of Am(III) and Eu(III) from HNO3. Synthesis of t-Bu-CyMe4-BTBP is described in detail. Metal nitrates are extracted from nitric acid in the form of 1:2 complexes, M(NO3)(3)(BTBP)(2). Whether in 1-octanol, kerosene, or cyclohexanone diluents, t-Bu-CyMe4-BTBP extracts with larger distribution ratios but with slower kinetics than CyMe4-BTBP. The general trends previously observed for CyMe4-BTBP regarding the diluent and modifier influence were also found for t-Bu-CyMe4-BTBP.
|
|
| 40. |
|
|
| 41. |
- Retegan Vollmer, Teodora, 1979
(author)
-
The influence of Diluents and Side Groups of the Ligands on Liquid-Liquid Extraction of Actinides and Lanthanides
- 2007
-
Licentiate thesis (other academic/artistic)abstract
- Fossil fuels are no longer a choice for energy production, both because of their diminishing availability and the bi-products of their combustion processes. A possibility to replace the fossil fuels would be utilization of nuclear power. No green-house gases are produced, but as any industry, it generates wastes.A proper plan for reusing valuable nuclides, both by preparing another kind of fuel or by transmutation, which, besides transforming the long-lived nuclides into short-lived ones, generates energy, seem to be P&T (partitioning and transmutation).The partitioning is the process of separation nuclides from the rest of the waste and involves a separation process which utilize an organic solvent containing one or several molecules and a diluent for extraction purposes.Among the last extractant families developed in Europe, 6,6’-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-benzo[1,2,4]triazin-3-yl)-[2,2’]bipyridine (BTBP) is the most promising molecule for an eventual industrial application. The present work focuses on several aspects insufficiently studied before and concerns strictly the BTBP family. The importance of the diluents regarding both the extraction capabilities of the formed system and the role of the diluents in protecting the molecule against radiolysiswithout adding a scavenging molecule will be discussed. The importance of the side groups added to the molecule first to facilitate dissolution, easing the phase transfer and thus enhancing the extraction capabilities and the role the side groups, in protecting the molecule against the radiolysis will also be discussed.Keywords: liquid-liquid extraction, Am, Eu, radionuclides, irradiation, side group, diluents.
|
|
| 42. |
- Roth, Vera, 1994, et al.
(author)
-
Mercury Removal from Concentrated Sulfuric Acid by Electrochemical Alloy Formation on Platinum
- 2023
-
In: ACS ES and T Engineering. ; 3:6, s. 823-830
-
Journal article (peer-reviewed)abstract
- Mercury is a highly toxic heavy metal, and improved removal processes are required in a range of industrial applications to limit the environmental impacts. At present, no viable removal methods exist commercially for mercury removal of aqueous solutions at high acidic conditions, such as concentrated sulfuric acid. Herein, we show that electrochemical mercury removal based on electrochemical alloy formation on platinum, forming PtHg4, can be used to remove mercury from concentrated sulfuric acid. Thin platinum film electrodes and porous electrodes with supported platinum are used to remove more than 90% of mercury from concentrated acid from a zinc smelter with an initial mercury concentration of 0.3-0.9 mg/kg, achieving high-quality acid (<0.08 mg/kg) within 80 h. The removal process is carried out in 50 mL laboratory-scale experiments and scaled up to a 20 L pilot reactor with retained removal efficiency, highlighting excellent scalability of the method. In addition, the removal efficiency and stability of different electrode substrate materials are studied to ensure high-quality acid and a long lifetime of the electrodes in harsh chemical conditions, offering a potential method for future large-scale mercury decontamination of sulfuric acid.
|
|
| 43. |
- Tari, Dogac, 1995, et al.
(author)
-
Reaction Capsule Design for Interaction of Heavy Liquid Metal Coolant, Fuel Cladding, and Simulated JOG Phase at Accident Conditions
- 2024
-
In: JOURNAL OF NUCLEAR ENGINEERING. - 2673-4362. ; 5:1, s. 57-73
-
Journal article (peer-reviewed)abstract
- High temperature corrosion of fuel cladding material (15-15Ti) in high burn-up situations has been an important topic for molten metal-cooled Gen-IV reactors. The present study aims to investigate the simultaneous impact of liquid lead (coolant side) and cesium molybdate (fuel side) on the cladding tube material. A capsule was designed and built for experiments between 600 degrees C and 1000 degrees C. In order to simulate a cladding breach scenario, a notch design on the cladding tube was investigated pre- and postexposure. Material thinning by corrosion and leaching at temperatures >= 900 degrees C caused breaches at the notches after 168 h exposure. The temperature dependent cladding thinning phenomenon was used for kinetic interpretation. As the first of a two-part study, this paper will focus on the exposure capsule performance, including metallographic cross-section preparation and preliminary results on the interface chemistry.
|
|
| 44. |
- Tiberiu Costin, Dan, 1983, et al.
(author)
-
Storage of defective fuel pins in SFR core
- 2016
-
In: Procedia chemistry. - : Elsevier BV. - 1876-6196. ; 21, s. 378-385
-
Journal article (peer-reviewed)abstract
- An open fuel pin failure is a breach in the fuel pin cladding that allows direct contact between the primary coolant and the nuclear fuel. In this paper we focus on the sodium-fuel interactions in a Sodium cooled Fast neutrons Reactor (SFR), reviewing the main aspects of the fuel pin failure evolution with an emphasis on the Reaction between the Oxide fuel and the Sodium (ROS). This reaction leads to the formation of an uranoplutonate phase with approximately half the density of the initial oxide. In turn this can cause significant fuel swelling and the potential further degradation of the fuel pin. The maximal fuel swelling due to the formation of the uranoplutonate can be estimated for non-irradiated fuel based on the physico-chemical properties of the pellets, as further described in this paper.
|
|
| 45. |
- Tiberiu Costin, Dan, 1983, et al.
(author)
-
Thermochemical effect of fission products on sodium – MOX fuel reaction: The case of niobium
- 2018
-
In: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115. ; 500, s. 361-365
-
Journal article (peer-reviewed)abstract
- The influence of niobium on the sodium MOX fuel chemical interaction was studied by different heat treatments of airtight capsules containing fresh MOX, sodium and a niobium strip. The characterisation results evidenced a two-step process with first MOX oxidation and then MOX reduction. This result was interpreted by considering the formation of sodium niobiate that captures oxygen from the MOX. This interpretation is used to discuss the influence of niobium as fission product on the sodium –irradiated MOX fuel reaction.
|
|
| 46. |
- Tunsu, Cristian, 1984, et al.
(author)
-
A hydrometallurgical process for the recovery of rare earth elements from fluorescent lamp waste fractions
- 2016
-
In: Separation and Purification Technology. - : Elsevier BV. - 1873-3794 .- 1383-5866. ; 161, s. 172-186
-
Journal article (peer-reviewed)abstract
- Rare earth elements (REEs) are presently regarded to be some of the most critical elements, being essential in future sustainable applications. One of the many examples is fluorescent lighting, which relies on REEs such as cerium, europium, gadolinium, lanthanum, terbium and yttrium. The high demand for REEs, low supply, price fluctuations and geopolitical factors have contributed to an increased interest in reclaiming these elements from end-of-life products. This publication reports on a new potential hydrometallurgical route to reclaim REEs in fluorescent lamp waste. The investigations were carried out at bench scale and laboratory pilot scale to assess the potential of a process based on leaching and solvent extraction. Real waste fractions of various compositions, originating from several companies that use different mechanical, physical and chemical processes to treat lamps, were studied. A multi-step leaching process that selectively dissolves different groups of metals in the waste was investigated. Removal of mercury, one of the vital constituents of fluorescent lamps and an undesired contaminant in the waste, was carried out using leaching with iodine in potassium iodide solutions. Selective leaching of impurity metals e.g. calcium and selective leaching of REEs was performed with nitric acid, taking advantage of the significant differences in their leaching kinetics. Separation of REEs was achieved with Cyanex 923, a commercial mix of trialkylphosphine oxides, in a counter-current mixer setter system comprising three extraction and four stripping stages, respectively. The product, a yttrium/europium concentrate, was treated with oxalic acid, followed by thermal treatment, to produce an oxide containing 99.96% REEs, of which 94.61% was yttrium and 5.09% was europium.
|
|
| 47. |
- Tunsu, Cristian, 1984, et al.
(author)
-
Characterization and leaching of real fluorescent lamp waste for the recovery of rare earth metals and mercury
- 2014
-
In: Hydrometallurgy. - : Elsevier BV. - 0304-386X. ; 144, s. 91-98
-
Journal article (peer-reviewed)abstract
- Current resource issues and the growing demand for metals used in advanced technologies have focused attention towards more efficient processing of end-of-life products and waste streams. Fluorescent lamp waste is a viable target for the recovery of rare earth metals (REMs); specifically cerium, europium, gadolinium, lanthanum, terbium, and yttrium. Waste originating from a discarded lamp processing facility was investigated using Scanning Electron Microscopy/Energy Dispersive Spectroscopy and X-ray Diffraction. Total dissolution experiments were carried out with aqua regia at elevated temperatures in order to estimate an average metal content and assess the recycling potential of the material. Leaching using different solutions (pure water, ammonium chloride, acetic acid, nitric and hydrochloric acid) and parameters (temperature, ultrasound-assisted digestion, solid: liquid ratio and leaching agent concentration) was investigated for the recovery of REMs and mercury. Cerium, europium, gadolinium, lanthanum, terbium, and yttrium were the REMs identified, with a total average content of 8.4 +/- 0.4 g/kg dry waste. An average of 0.7 +/- 0.1 g mercury/kg dry waste was quantified. Partial removal of impurities from the material raised the average REMs content to 105.7 +/- 5.3 g/kg waste. Pure water and ammonium chloride solution (1 M) performed poorly as leachants. Efficient leaching of europium and yttrium (over 95%, respectively 97% dissolution) was achieved in less than 24 h at 20 +/- 1 degrees C, using weak nitric and hydrochloric acid solutions (0.5 M). Leaching of cerium, gadolinium and terbium occurred slowly and did not reach equilibrium even after 96 h. An increased acid concentration and increased temperature, and ultrasound-assisted digestion improved the leaching efficiency for all investigated elements. Hydrochloric acid proved to be as efficient as nitric acid when it comes to solubilizing most REMs. The former showed better efficiency for mercury: 89.6 +/- 3.3% vs. 23.2 +/- 0.3%, when using a 4 M solution. Acetic acid (25% v/v solution) dissolved approx. 50% of the europium, 75% of all yttrium, between 2 and 10% of the other REMs, and just over 2% of the mercury. Based on the observations, several processing methods are suggested for the samples investigated.
|
|
| 48. |
|
|
| 49. |
- Tunsu, Cristian, 1984, et al.
(author)
-
Hydrometallurgical Processes for the Recovery of Metals from WEEE
- 2016
-
In: WEEE Recycling: Research, Development, and Policies. ; , s. 139-175
-
Book chapter (other academic/artistic)abstract
- Pyrometallurgy and hydrometallurgy are two routes usually implemented to recover valuable metals from primary and secondary resources. In recent years, the metallurgical industry has been searching for hydrometallurgical processes as an alternative to pyrometallurgical treatments due to some inherent advantages associated with hydrometallurgy, such as the possibility of treating low-grade resources, easier control of wastes, and lower energy consumption. This chapter will give an overview of the hydrometallurgical processes developed to recover metals from waste electrical and electronic equipment (WEEE), including leaching, precipitation, solvent extraction, and resin ion exchange.
|
|
| 50. |
- Tunsu, Cristian, 1984, et al.
(author)
-
Investigations regarding the wet decontamination of fluorescent lamp waste using iodine in potassium iodide solutions
- 2015
-
In: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 36, s. 289-296
-
Journal article (peer-reviewed)abstract
- With the rising popularity of fluorescent lighting, simple and efficient methods for the decontamination of discarded lamps are needed. Due to their mercury content end-of-life fluorescent lamps are classified as hazardous waste, requiring special treatment for disposal. A simple wet-based decontamination process is required, especially for streams where thermal desorption, a commonly used but energy demanding method, cannot be applied. In this study the potential of a wet-based process using iodine in potassium iodide solution was studied for the recovery of mercury from fluorescent lamp waste. The influence of the leaching agent's concentration and solid/liquid ratio on the decontamination efficiency was investigated. The leaching behaviour of mercury was studied over time, as well as its recovery from the obtained leachates by means of anion exchange, reduction, and solvent extraction. Dissolution of more than 90% of the contained mercury was achieved using 0.025/0.05 M I-2/KI solution at 21 degrees C for two hours. The efficiency of the process increased with an increase in leachant concentration. 97.3 +/- 0.6% of the mercury contained was dissolved at 21 degrees C, in two hours, using a 0.25/0.5 M I-2/KI solution and a solid to liquid ratio of 10% w/v. Iodine and mercury can be efficiently removed from the leachates using Dowex 1X8 anion exchange resin or reducing agents such as sodium hydrosulphite, allowing the disposal of the obtained solution as non-hazardous industrial wastewater. The extractant CyMe4BTBP showed good removal of mercury, with an extraction efficiency of 97.5 +/- 0.7% being achieved in a single stage. Better removal of mercury was achieved in a single stage using the extractants Cyanex 302 and Cyanex 923 in kerosene, respectively.
|
|
