| 1. |
- Kajan, Ivan, 1984, et al.
(författare)
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Interaction of ruthenium tetroxide with surfaces of nuclear reactor containment building
- 2016
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Ingår i: Journal of Nuclear Science and Technology. - : Informa UK Limited. - 0022-3131 .- 1881-1248. ; 53:9, s. 1397-1408
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Tidskriftsartikel (refereegranskat)abstract
- © 2016 Atomic Energy Society of Japan. All rights reserved. During a severe nuclear accident, different fission products will be released from the nuclear fuel and some of them may eventually reach the containment building. Ruthenium is considered to be an important fission product due to the possible formation of volatile oxides. Radiotoxicity and chemical toxicity of the volatile ruthenium compounds present a considerable hazard during a severe nuclear accident. In this work, experiments regarding behavior of ruthenium tetroxide in the reactor containment were performed. The interactions of ruthenium tetroxide (RuO4) with zinc, copper, aluminum and epoxy paint in dry and humid atmosphere were examined. SEM/EDX (scanning electron microscope/energy-dispersive X-ray spectroscopy), XPS (X-ray photoelectron spectroscopy) and EXAFS (extended X-ray absorption fine structure) techniques were used to identify the chemical composition of the deposits formed after the interaction of RuO4 with the different materials. Additionally, distribution of ruthenium between different metals was examined. Interaction of RuO4 with the studied samples led to formation of dark, ruthenium-rich deposits. Examination of these deposits showed different chemical speciation of ruthenium on the surface when compared to the deeper layers of deposits. Interaction of RuO4 with zinc, copper and aluminum resulted to different amounts of the deposited ruthenium on the metals.
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| 2. |
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| 3. |
- Lassesson, Henric, 1979, et al.
(författare)
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Leaching for recovery of copper from municipal solid waste incineration fly ash: Influence of ash properties and metal speciation.
- 2014
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Ingår i: Waste Management and Research. - 1096-3669 .- 0734-242X. ; 32:8, s. 755-762
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Tidskriftsartikel (refereegranskat)abstract
- Recovery of metals occurring in significant amounts in municipal solid waste incineration fly ash, such as copper, could offer several advantages: a decreased amount of potentially mobile metal compounds going to landfill, saving of natural resources and a monetary value. A combination of leaching and solvent extraction may constitute a feasible recovery path for metals from municipal solid waste incineration fly ash. However, it has been shown that the initial dissolution and leaching is a limiting step in such a recovery process. The work described in this article was focused on elucidating physical and chemical differences between two ash samples with the aim of explaining the differences in copper release from these samples in two leaching methods. The results showed that the chemical speciation is an important factor affecting the release of copper. The occurrence of copper as phosphate or silicate will hinder leaching, while sulphate and chloride will facilitate leaching.
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| 4. |
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| 5. |
- Lassesson, Henric, 1979, et al.
(författare)
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Speciation of Copper in Ash from a Fluidized-Bed Boiler Fired with Municipal Solid Waste
- 2013
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 27:7, s. 3891-3897
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Tidskriftsartikel (refereegranskat)abstract
- Copper is one of the most important trace elements in municipal solid waste (MSW) combustion. Knowledge of the speciation of copper is fundamental for the understanding of the effects of copper compounds on the combustion chemistry, the evaluation of the environmental effects of copper in ash leachates, and the development of methods to recover copper from the MSW combustion ash. In this work, an investigation of the speciation of copper in four ash flows from a bubbling fluidized-bed boiler using synchrotron-based X-ray absorption spectrometry is reported. The results showed that copper occurs in oxidation states 0, +1, and +2 in the bed ash and the cyclone ash, i.e., 10-20% Cu-0, 25-35% Cu-I, and 50-60% Cu-II, whereas the filter ash contained copper only in oxidation state +2. The most common copper compounds in the bed ash are copper metal, Cu2O, CuO, and mixed oxides, such as CuCr2O4. The cyclone ash probably contained a mix of copper metal, Cu2O, CuCl, Cu(OH)(2), and CuSO4 center dot 5H(2)O, possibly also CuO. Copper sulfate was found as one of the major species in the filter ash together with a mix of hydroxides and chlorides.
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| 6. |
- Lassesson, Henric, 1979
(författare)
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Speciation of copper in ashes from municipal solid waste combustion
- 2013
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Copper is one of the most important trace elements in municipal solid waste (MSW) combustion. Knowledge of the speciation of copper is fundamental for the understanding of the effects of copper compounds on the combustion chemistry as well as of the environmental impact of the ash. An increased understanding of the chemistry of copper in combustion and in the ashes could support the development of management and recycling techniques, not only for the copper metal but also for the bulk of the ash. It could also increase the understanding of how it might be possible to reduce the amount of dioxins formed and thereby reducing the toxicity of the ashes as well as the flue gases. In this work the speciation of copper in four ash flows from a bubbling fluidized bed (BFB) boiler and one fly ash from a grate fired mass burn (MB) combustor has been investigated using synchrotron based X-ray absorption spectrometry. Additionally the copper speciation of leaching residues from the BFB filter ash and MB fly ash, leached in ammonium nitrate and nitric acid, have also been investigated. The results from the BFB ash flows showed that copper occurred mainly as copper metal, copper oxides and mixed oxides in the ashes from and close to the combustion bed. The concentrations of copper sulphate, hydroxides and chlorides increased further down the BFB flue gas system, closer to the filter. Copper in oxidation states 0, +I and +II was found in all ash flows, except in the BFB filter ash where mainly copper(II) was found. The MB fly ash showed significantly different copper speciation than in the BFB fly ash, with mainly phosphate or silicate together with a mix of copper metal, copper(II) oxide and copper(I) chloride. The residues from leaching with ammonium nitrate showed that the copper speciation was similar in both residues, containing a mix of mainly phosphate or silicate together with a mix of copper(II) oxide and copper(I) chloride. The results showed that the chemical speciation may be an important factor affecting the release of copper. This work also included the collection of XAS-data for a large number of copper compounds that could possibly be present in ashes. This collection of XAS-data will be useful in future work.
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| 7. |
- Poulikidou, Sofia, 1984, et al.
(författare)
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Impacts on fuel producers and customers of conflicting rules for life cycle assessment
- 2022
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The use of life cycle assessment (LCA) as a tool for estimating the environmental performance of a product or service in a holistic and systematic manner is increasing. Fuel producers may need to apply different methodological frameworks to be used in different contexts; internally for product development activities as well as externally for communication with customers or authorities. Different LCA frameworks may vary in scope, system boundaries (i.e. life cycle stages to be considered) or modelling requirements (such as data demands but also more detailed methodological features). They may also vary in terms of information they can provide in relation to the environmental performance of the product. Those variations could lead to conflicting outcomes and conclusions and may also increase complexity for the LCA practitioner leading to high competence and resource requirements. Within the research project: Impacts on fuel producers and customers of conflicting rules for LCA , the requirements of different LCA frameworks and their implications to fuel producers are investigated. Focus has been given on three specific frameworks that are identified as relevant or potentially relevant for fuel producers, namely: the recast of the EU Renewable Energy Directive (referred to here as RED II), the EU framework for Product Environmental Footprint (PEF), and the framework of Environmental Product Declaration (EPD). The aim of the project is to increase understanding on the different LCA frameworks available and identify whether the multitude of such frameworks gives conflicting recommendations for environmental improvements and fuel choices. The three LCA frameworks listed above were applied in case studies. To illustrate the potential differences that the different frameworks may lead to, a variation of production pathways and feedstocks were selected including first generation as well as advanced biofuels. Based on the results obtained it can be concluded that applying all three frameworks is not a straightforward task. The methods contain fundamental differences and are at different levels of development, maturity, and adoption. In certain situations, they can lead to diverging conclusions as a result of different quantitative outcomes for a specific production pathway, thus influencing decision making processes in different directions. Understanding those differences and underlying assumptions is important for understanding the variations in outcome. The result for a specific fuel could differ substantially depending on the framework applied and the assumptions and interpretations made when applying this framework. Certain methodological parameters were identified to have a greater impact on the results than others: • The three frameworks diverge in the methods applied for modelling waste management, which can be very important for the results when the biofuel is produced from waste. • The frameworks diverge in what approaches are allowed for modelling processes with multiple products. This can be very important for the results when the fuel is co-produced with other products. • The frameworks also diverge in how the electricity supply is modelled. This is not very important for the results in most of our case studies, because the production of these biofuels does not require a lot of electricity. The study confirms that applying a framework like EPD or PEF in addition to RED II would require significant supplementary efforts. Not only because of different rules which were often contradicting or difficult to interpret but also because of additional data and reporting requirements. The need for expertise and resources is increasing for fuel producers to be able to provide EPD and PEF compliant assessments. To enhance the development and harmonization of LCA approaches this project stresses the need for product specific rules (in the form of Product Environmental Category Rules (PEFCR) and Product Category Rules (PCR)) for renewable fuels. Future versions of all three studied frameworks should be clearer on how specific methodological choices are to be applied (e.g., when it comes to allocation and multifunctional processes) as well as when it comes to model electricity supply. RED for example shall be clearer on how to define the electricity region while EPD guidelines on how to define the electricity market. Although it is not realistic to aim for a single unified LCA framework, the biofuel PCR and PEFCR can be developed with RED in mind. Some aspects of the PEF methodology can perhaps also be integrated into RED III that is currently under development. This would enhance the broader adoption of the frameworks among fuel producers. Finally, the involvement and engagement of the industry, and fuel producers themselves is very important. Industry initiatives are essential for the development of biofuel PCR and PEFCR while the general development of the three frameworks can also be influenced. In this study, we also investigated the relationship between the LCA frameworks and schemes for chain of custody certification (CoCC), in particular schemes for mass balance certifications (MBC) to investigate to what extent these schemes complement or overlap with LCA. The purpose of MBC schemes and LCA are different, in the sense that the first aim at verifying the sources and sustainability of total amounts of raw materials used by tracking them throughout the value chain, while the second at quantifying specific environmental impact. The system boundaries are similar, since both cover the entire value chain, but may be applied differently depending on the detailed frameworks applied and choices made in applying the MBC schemes. By identifying and clearly illustrating the variations among the studied frameworks the study enhances application, development, and harmonization of LCA, in a broader perspective, informs LCA practitioners but also decision makers and provides insights on how the identified challenges can be addressed.
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| 8. |
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| 9. |
- Tang, Jinfeng, 1984, et al.
(författare)
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Resource recovery from municipal solid waste ash
- 2014
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Ingår i: Proceedings of the 29th International Conference on Solid Waste Technology and Management, Philadelphia, PA U.S.A., March 30-April 2, 2014. - 1091-8043. ; , s. 352-361
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Ashes from municipal solid waste incineration (MSWI) may be a cumbersome waste to handle. Some ash fractions contain organic pollutants, such as dioxins, as well as heavy metals. Additionally, some of the metals have a high value and are considered as critical to the industry. Recovery of e.g. copper and zinc from MSWI ashes will not only recover valuable metals that would otherwise be land filled, but also reduce the toxicity of the ash and thereby make it less cumbersome to handle.Such processes are presently being investigated by the Industrial Materials Recycling group at Chalmers University of Technology. The processes are primarily based on acid leaching of the ash combined with selective solvent extraction. The work on recovery process development is supported by investigations of the chemical speciation of metals, i.e. identification of metal compounds, in ashes by, e.g. synchrotron based X-ray absorption spectroscopy (XAS).The presentation will give an introduction to the validation of an optimized leaching process for MSWI and speciation results for Cu and Zn, as well as discuss the promising results that have been obtained using the suggested recovery processes for these metals.
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