| 1. |
- Tyumentsev, Mikhail S, 1988, et al.
(author)
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Coordination of Trivalent Lanthanides with Bismalonamide Ligands: Implications for Liquid-Liquid Extraction
- 2017
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In: European Journal of Inorganic Chemistry. - : Wiley. - 1434-1948 .- 1099-0682. ; 2017:37, s. 4285-4298
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Journal article (peer-reviewed)abstract
- The complexation of the bismalonamide ligand 2,2'[1,2-phenylenebis(methylene)] bis(N, N, N', N'-tetraethylmalonamide) (L), bearing two C-alkylated N, N, N', N'-tetraethylmalonamide groups, onto an ortho-xylylene [C6H4(CH2)(2)] platform with trivalent lanthanides was investigated, both in solid and solution states. The crystal structures [Nd-2(NO3)(6)L-2]center dot(CH3CN)(3) (2), [Nd-2(NO3)(4)L-2]center dot[Nd(NO3)(5)]center dot(CH3CN) 1.5 (3), Ce(NO3)(3)L-2 (4), and [NdL2]center dot(ClO4)(3)center dot C2H5OH (5) were analyzed by single-crystal X-ray diffraction. The ortho-bismalonamide (L) is tetradentate in structures 2, 3, and 5 and bidentate in 4 only. It was found that structures 2 and 3 are composed of dimeric species. According to electrospray-ionization mass spectrometry, the dimers are prevailing in acetonitrile solutions. The polydentate coordination of the ortho-bismalonamide (L) with trivalent lanthanides suggests that an entropy effect favors liquid-liquid extraction of metal ions with this type of ligand.
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| 2. |
- Ylmén, Rikard E, 1982, et al.
(author)
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DR-FTIR method for the study of early hydration of cement
- 2008
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In: Conference Proceedings for “SCC 2008: Challenges and Barriers to Application.
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Conference paper (peer-reviewed)abstract
- A method has been developed to study early hydration reactions of ordinary Portland cement using freeze drying and Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DR-FTIR). The hydration process was studied after 3 minutes up to 2 hours. The cement samples were mixed and after different hydration times the samples were placed in frozen liquid hydrogen to stop the hydration process. The samples were freeze dried under vacuum and analyzed with DR-FTIR. Measurements were also made on cement that was only dried in vacuum. The results showed that the freezing of the cement instantly stopped without any further hydration. This makes it possible to monitor chemical changes during very early hydration stages of cement by using the freeze drying combined with DR-FTIR. It was also possible to dry the samples with only vacuum, but then it was not possible to study the hydration process on a short timescale. Comparison between frozen and non-frozen samples showed that the freezing do not cause any detectable differences. This clearly indicates that the freezing do not change the chemical or physical structure of the samples to any larger extent. The freezing of the samples gave a much better time resolution and made it easier to handle the samples technically as they could be stored in the liquid nitrogen and put in the freeze drier together. The vacuum dried samples on the other hand had to be put in the drier at specified times. After a sample is put in the drier, vacuum has to be established and the sample must be sufficiently dry for the hydration to stop. This limits the time resolution of the vacuum technique in this study at best to a few minutes. The limiting time step of the freezing technique is the time for freezing the samples, which in this study was a few seconds.
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| 3. |
- Tang, Jinfeng, 1984, et al.
(author)
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Comparative study of the application of traditional and novel extractants for the separation of metals from MSWI fly ash leachates
- 2018
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In: Journal of Cleaner Production. - : Elsevier BV. - 0959-6526. ; 172, s. 143-154
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Journal article (peer-reviewed)abstract
- Municipal Solid Waste Incineration (MSWI) fly ash often has to be managed as a hazardous waste due to its content of toxic metals in leachable forms. Some of the metals are also quite valuable and should not be lost in a landfill. In the present work a novel commercial extractant, Cyanex 572, was applied for selective separation of zinc from other metals in an ash leachate and its efficiency was compared to that of Cyanex 923 and Cyanex 272. Cyanex 572 was found to be more selective towards zinc than the other extractants and gave less co-extraction of other metals. Furthermore, the configurations of the complexes formed between metal ions and the respective extractants were investigated using both experimental data and theoretical modelling. Hydrometallurgical processes based on the use of Cyanex 572 and Cyanex 923, respectively, were tested and gave zinc recovery yields of 91% and 76%, respectively. Extraction with Cyanex 923 is not pH dependent like those of the other extractants, however it does extract part of the acid as well as the metal ions. The stripping processes, i.e. the recovery of extracted metal ions from the organic phases, are simpler with Cyanex 572 than with Cyanex 923 and create less secondary waste. These results show that Cyanex 572 can be an economically and environmentally suitable extractant for the recovery of zinc and other metals from MSWI fly ash. Further work to verify this includes modelling of the number of mixer settler stages needed for the extraction and stripping steps, as well as demonstration of the entire process in a pilot scale mixer settler set up.
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| 4. |
- Ylmén, Rikard E, 1982, et al.
(author)
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Recovery of phosphorous from industrial waste water by oxidation and precipitation
- 2018
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In: Environmental Technology (United Kingdom). - : Informa UK Limited. - 1479-487X .- 0959-3330. ; 39:15, s. 1886-1897
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Journal article (peer-reviewed)abstract
- This paper describes the development of a method for recovery of phosphorous from one of the waste waters at an Akzo Nobel chemical plant in Ale close to Göteborg. It was found that it is possible to transform the phosphorous in the waste water to a saleable product, i.e. a slowly dissolving fertilizer. The developed process includes oxidation of phosphite to phosphate with hydrogen peroxide and heat. The phosphate is then precipitated as crystalline struvite (ammonium magnesium phosphate) by the addition of magnesium chloride. The environmental impacts of the new method were compared with those of the current method using life cycle assessment. It was found that the methodology developed in this project was an improvement compared with the current practice regarding element resource depletion and eutrophication. However, the effect on global warming would be greater with the new method. There could however be several ways to decrease the global warming effect. Since most of the carbon dioxide emissions come from the production of magnesium chloride from carbonates, changing to utilization of a magnesium chloride from desalination of seawater or from recycling of PVC would decrease the carbon footprint significantly.
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