| 1. |
- Essalhi, Mohamed, et al.
(författare)
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Polyvinylidene fluoride membrane formation using carbon dioxide as a non-solvent additive for nuclear wastewater decontamination
- 2022
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Ingår i: Chemical Engineering Journal. - : Elsevier. - 1385-8947 .- 1873-3212. ; 446:4
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Tidskriftsartikel (refereegranskat)abstract
- Polyvinylidene fluoride (PVDF) membranes were prepared by phase inversion in the most commonly used solvents for membrane manufacture, with CO2 as a non-solvent additive. The effects of changing the polymer concentration (10, 12.5 and 15% by weight), the type of solvent (NMP, DMAc and DMF) and the coagulation bath with three levels of CO2 concentration on the phase inversion process, as well as the phase diagram, morphology and transport properties of the membranes were studied. The best performing membranes were used to desalinate salt aqueous solutions and decontaminated simulated nuclear wastewater by membrane distillation using two configurations (DCMD and AGMD). All selected membranes showed high rejection with acceptable permeate fluxes reaching an infinite decontamination factor. The proposed approach of this novel idea of using CO2 dissolved in water as a coagulation medium in the field of membranes avoids the increase of the harmful effect on the environment caused by the addition of a harsh non-solvent to the coagulation bath. It constitutes a beneficial use of carbon dioxide that reduces the negative environmental impact of membrane manufacturing and represents a decisive step towards its sustainability. Furthermore, this study highlights the potential benefits of using these membranes in DM for desalination and treatment of simulated nuclear wastewater.
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| 2. |
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| 3. |
- Knighton, Richard C., et al.
(författare)
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Solution, Solid-State, and Computational Analysis of Agostic Interactions in a Coherent Set of Low-Coordinate Rhodium(III) and Iridium(III) Complexes
- 2018
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Ingår i: Chemistry - A European Journal. - : John Wiley & Sons. - 0947-6539 .- 1521-3765. ; 24:19, s. 4927-4938
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Tidskriftsartikel (refereegranskat)abstract
- A homologous family of low‐coordinate complexes of the formulation trans‐[M(2,2′‐biphenyl)(PR3)2][BArF4] (M=Rh, Ir; R=Ph, Cy, iPr, iBu) has been prepared and extensively structurally characterised. Enabled through a comprehensive set of solution phase (VT 1H and 31P NMR spectroscopy) and solid‐state (single crystal X‐ray diffraction) data, and analysis in silico (DFT‐based NBO and QTAIM analysis), the structural features of the constituent agostic interactions have been systematically interrogated. The combined data substantiates the adoption of stronger agostic interactions for the IrIII compared to RhIII complexes and, with respect to the phosphine ligands, in the order PiBu3>PCy3>PiPr3>PPh3. In addition to these structure–property relationships, the effect of crystal packing on the agostic interactions was investigated in the tricyclohexylphosphine complexes. Compression of the associated cations, through inclusion of a more bulky solvent molecule (1,2‐difluorobenzene vs. CH2Cl2) in the lattice or collection of data at very low temperature (25 vs. 150 K), lead to small but statistically significant shortening of the M−H−C distances.
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| 6. |
- Ohlin, C. Andre, et al.
(författare)
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The first peroxotitanoniobate cluster - [N(CH3)(4)](10)[Ti12Nb6O38(O-2(I))(6)]
- 2010
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Ingår i: Inorganica Chimica Acta. - : Elsevier BV. - 0020-1693 .- 1873-3255. ; 363:15, s. 4405-4407
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Tidskriftsartikel (refereegranskat)abstract
- The synthesis and structure of the first discrete peroxotitanoniobate cluster, [N(CH3)(4)](10)[Ti12Nb6O38(O-2(I))(6)], is described. (C) 2010 Elsevier B.V. All rights reserved.
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| 7. |
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| 8. |
- Panasci, Adele F., et al.
(författare)
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Cooperation between bound waters and hydroxyls in controlling isotope-exchange rates
- 2012
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Ingår i: Geochimica et Cosmochimica Acta. - : Elsevier BV. - 0016-7037 .- 1872-9533. ; 78, s. 18-27
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Tidskriftsartikel (refereegranskat)abstract
- Mineral oxides differ from aqueous ions in that the bound water molecules are usually attached to different metal centers, or vicinal, and thus separated from one another. In contrast, for most monomeric ions used to establish kinetic reactivity trends, such as octahedral aquo ions (e.g., Al(H(2)O)(6)(3+)), the bound waters are closely packed, or geminal. Because of this structural difference, the existing literature about ligand substitution in monomer ions may be a poor guide to the reactions of geochemical interest. To understand how coordination of the reactive functional groups might affect the rates of simple water-exchange reactions, we synthesized two structurally similar Rh(III) complexes, [Rh(phen)(2)(H(2)O)(2)](3+) [1] and [Rh(phen)(2)(H(2)O)Cl](2+) [2] where (phen) = 1,10-phenanthroline. Complex [1] has two adjacent, geminal, bound waters in the inner-coordination sphere and [2] has a single bound water adjacent to a bound chloride ion. We employed Rh(III) as a trivalent metal rather than a more geochemically relevant metal like Fe(III) or Al(III) to slow the rate of reaction, which makes possible measurement of the rates of isotopic substitution by simple mass spectrometry. We prepared isotopically pure versions of the molecules, dissolved them into isotopically dissimilar water, and measured the rates of exchange from the extents of (18)O and (16)O exchange at the bound waters. The pH dependency of rates differ enormously between the two complexes. Pseudo-first-order rate coefficients at 298 K for water exchanges from the fully protonated molecules are close: k(0)(298) = 5 x 10(-8) (+/- 0.5 x 10(-8)) s(-1) for [1] and k(0)(298) = 2.5 x 10(-9)(+/- 1 x 10(-9)) for [2]. Enthalpy and entropy activation parameters (Delta H(double dagger) and Delta S(double dagger)) were measured to be 119(+/- 3) kJ mol(-1), and 14(+/- 1) J mol(-1) K(-1), respectively for [1]. The corresponding parameters for the mono-aquo complex, [2], are 132(+/- 3) kJ mol(-1) and 41.5(+/- 2) J mol(-1) K(-1). Rates increase by many orders of magnitude upon deprotonation of one of the bound waters in complex [1] because of the close proximity of a transferable proton that can convert the bound hydroxyl to a bound water. This interconversion allows the oxygen to exchange as a bound water, rather than as a bound hydroxyl, which is slow at near-neutral pH conditions. (C) 2011 Elsevier Ltd. All rights reserved.
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| 9. |
- Pilgrim, C. D., et al.
(författare)
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27Al MQMAS of the δ-Al13-Keggin†
- 2017
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Ingår i: Dalton Transactions. - 1477-9226 .- 1477-9234. ; 46:7, s. 2249-2254
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Tidskriftsartikel (refereegranskat)abstract
- One-dimensional 27Al, 23Na Magic-Angle-Spinning (MAS) NMR and 27Al Multiple-Quantum Magic-Angle-Spinning NMR (MQMAS) measurements are reported for the [small delta]-isomer of the Al13 Keggin structure at high spinning speed and 14.1 T field. Values for the CQ and [small eta] parameters are on the same scale as those seen in other isomers of the Al13 structure. Density functional theory (DFT) calculations are performed for comparison to the experimental fits using the B3PW91/6-31+G* and PBE0/6-31+G* levels of theory, with the Polarizable Continuum Model (PCM).
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| 10. |
- Son, Jung-Ho, et al.
(författare)
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Synthesis and Characterization of a Soluble Vanadium-Containing Keggin Polyoxoniobate by ESI-MS and 51V NMR : (TMA)9[V3Nb12O42]center dot 18H2O
- 2013
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Ingår i: European Journal of Inorganic Chemistry. - : Wiley. - 1434-1948 .- 1099-1948 .- 1099-0682. ; :10-11, SI, s. 1748-1753
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Tidskriftsartikel (refereegranskat)abstract
- The vanadium-containing heteropolyoxoniobate (TMA)9[V3Nb12O42]center dot 18H2O was synthesised by hydrothermal reaction of V2O5 and hydrous niobium oxide in tetramethylammonium hydroxide solution. The cluster has an -Keggin structure with a central VO4 and two trans-bicapped VO5. The water-soluble product was characterised by X-ray crystallography, ESI-MS and both liquid- and solid-state 51V NMR spectroscopy. The solid- and solution-phase 51V NMR spectra indicate two major peaks corresponding to one VO4 and two VO5 sites.
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