Research of the Changes in the Structural Group Composition of Transformer Oil During Operation

The actual issue of the electric power industry is the diagnostics of equipment to timely detection of emerging defects and their prevention. The aim of presented work is the development of a method for monitoring the state of transformer equipment based on the determination of structural-group composition of transformer oil. The goal is achieved by measuring spectra of oil in the near-IR (infrared) region. The method of investigation isapproximation of obtained spectra of transformer oils on the basis of reference compoundsspectra.A new method for determining the structural group composition of oils was proposed. It is distinguished by a significant simplicity and directly related to the characteristics of the molecules in comparison with the existing methods for determining the structural group composition from nomograms.Optical spectra in the near-IR range of fresh and used samples of GK transformer oil in the range of 10250-11750 cm-1were recorded and analyzed. It was shown that during the aging transformer oil fraction of CH2-groups decreases, CH3-groups fraction increases somewhat, CH-groups fraction is significantly increased, thereby confirming the effect of increasing the proportion of aromatics in such systems reducing the amount of cycloalkanes, paraffins are most stable. This fact can be used to develop monitoring systems for power oil-filled transformers. Determination of the structural group composition of the oil and its changes during operation will allow monitoring the oil condition, the technical condition of the transformer and to determine the origin of thermal and discharge defects

Solvent extraction of intra-lanthanides using a mixture of TBP and TODGA in ionic liquid

International audienceIn this study, we have investigated the solvent extraction of yttrium(III) and lanthanide(III) ions from nitric acid solutions in an organic phase consisting of a mixture of two electrically neutral extractants, namely tri-n-butyl phosphate(TBP) and N,N,N',N'-tetra(n-octyl)diglycolamide (TODGA). We employed hydrophobic room-temperature ionic liquid 1-methyl-3-butyl-imidazolium bis(trifluoromethanesulfonyl)imide as more environmentally benign diluent as compared to conventional molecular solvents. The results revealed that the addition of TBP as a co-extractant to TODGA dissolved in this ionic liquid not only enhance greatly the metal ion extraction, but also induce high intra-lanthanide ion selectivity. This was attributed to the formation of complex lanthanide species with both organic extracting agents, TBP and TODGA. In addition, when IL is used as diluent, cationic exchange between metal-organic ligand species and IL cations and neutral complex extraction result in more efficient extraction. Moreover, hydrophobic anionic IL entities could be also involved in the extraction mechanism resulting in the lipophilic metal-organic ligand complexes. The synergic solvent combination of TODGA, TBP and ionic liquid offers a possibility of excellent separation among the lanthanide(III) ions

Synergistic extraction of uranium(VI) with TODGA and hydrophobic ionic liquid mixtures into molecular diluent

International audienceThe extraction of uranium(VI) from aqueous nitric acid solutions with a neutral extractant, N,N,N 0 ,N 0-tetra (n-octyl)diglycolamide (TODGA), and with the mixtures of TODGA and a hydrophobic ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C 4 mim][Tf 2 N]), into a molecular diluent, 1,2-dichloroethane, has been systematically investigated. The extraction efficiency of U(VI) ions was greatly enhanced by addition of a small amount of ionic liquid to an organic phase containing TODGA. The synergistic effect comes from the higher hydrophobicity of U(VI) extracted species formed by TODGA and weakly coordinating Tf 2 N À anions as compared to those formed by TODGA and NO 3 À anions as counterions in the conventional extraction system. Based on our experimental results, we concluded that the partition of Tf 2 N À anions between the two liquid phases is the dominant factor governing the extractability of uranium(VI) with the mixture of TODGA and ionic liquid as extractant. We showed that the extraction of U(VI) from aqueous nitric acid solutions both by TODGA alone and its mixtures with [C 4 mim][Tf 2 N] into 1,2-dichloroethane can be quantitatively described on the basis of the solvation extraction mechanism. However, in the extraction system with added hydrophobic ionic liquid, the partition of Tf 2 N À anions between the two immiscible phases and the interaction between bis(trifluorome thylsulfonyl)imide acid, HTf 2 N, and TODGA molecules in the organic phase should be taken into account

Extraction de l’uranium(VI) avec un mélange de TODGA et d’un liquide ionique dans un solvant moléculaire

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Ionic liquids for the recovery of metallic species

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