Catarina Maia Seco Seiça Neves Sistemas Aquosos Bifásicos com ...

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Aqueous Biphasic Systems with Ionic Liquids _________________________________________________________________________ 42 [IL] / (mol. kg -1 ) 6.0 5.0 4.0 3.0 2.0 1.0 Monophasic Region Biphasic Region 0.0 0.0 0.5 1.0 1.5 2.0 2.5 [K3PO4] / (mol. kg-1 ) Figure 18. Phase diagram for the di-substituted imidazolium-based ternary systems composed by IL + K3PO4 + H2O at 298 K: , [C1mim][Cl]; ■, [C2mim][Cl]; □, [C4mim][Cl]; , [C6mim][Cl]; +, [C7H7mim][Cl]; ◊, [amim][Cl]; ▲, [OHC2mim][Cl]. The observation of Figure 18 indicates that the larger the cation alkyl chain the greater it is the IL ability for ABS formation. It is well known that the cation alkyl chain length increase leads to the increase of the IL hydrophobic nature and therefore to a poorer affinity for water 57 . The higher the IL affinity for water and/or the IL hydrophilic nature the less effective is the IL in promoting ABS. Moreover, the presence of a terminal hydroxyl group at the alkyl chain leads to a large decrease in the ABS promoting ability due to the higher hydrophilicity of the IL when compared with the [C2mim][Cl]. Also the presence of a double bond at the propyl chain of the imidazolium cation ([amim][Cl]) or the presence of a benzyl group ([C7H7mim][Cl]) as a substituent group decreases the ABS formation ability, although in a less pronounced way. When a second electrolyte is added to a non-electrolyte or electrolyte aqueous solution, the solubility of the solute usually decreases as a consequence of the salting-out effect. In general, ILs with lower water solubility require less salt to promote the two phases
ILs + H2O + K3PO4 Ternary Systems _________________________________________________________________________ separation resulting in a binodal curve closer to the axis and in a larger biphasic region. The results here obtained show that the ability of the ILs for ABS formation follows the order: [C6mim][Cl] > [C7H7mim][Cl] > [C4mim][Cl] > [C2mim][Cl] [amim][Cl] > [C1mim][Cl] > [OHC2mim][Cl]. Figure 19 illustrates the experimental binodal curves obtained for the mono- and un- substituted imidazolium chlorides [C2im][Cl], [C1im][Cl] and [im][Cl]. [IL] / (mol. kg -1 ) 3.0 2.5 2.0 1.5 1.0 0.5 Monophasic Region Biphasic Region 0.0 0.0 0.5 1.0 1.5 2.0 2.5 [K3PO4] / (mol. kg-1 ) Figure 19. Phase diagram for the un- and mono-substituted imidazolium-based ternary systems composed by IL + K3PO4 + H2O at 298 K: ○, [im][Cl]; ▬ , [C1im][Cl] and Δ, [C2im][Cl]. These systems reveal an “atypical” behaviour for ABS involving ILs not previously reported. The asymmetrical behaviour of these aqueous biphasic systems has been previously observed for ABS of polyethylene glycol (PEG) and low weight polysaccharides 72, 73 and they may constitute an interesting approach for product separations. For the same K3PO4 molality two monophasic and one biphasic regions are present and thus the system can be moved between the various phases by simple variation 43
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Catarina Maia Seco Seiça Neves Uni
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Ao meu Pai e ao meu Avô…
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agradecimentos Gostaria de começar
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keywords abstract Ionic liquids, wa
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4.2.3. Partitioning of L-tryptophan
Page 19 and 20: List of Abbreviations ABS Aqueous B
Page 21 and 22: List of Tables Table 1. Experimenta
Page 23 and 24: List of Figures Figure 1. Example o
Page 25 and 26: [C4mim][TFA]; ×, [C4mim][Br]; ○,
Page 27: 1. 1. General Introduction
Page 30 and 31: Aqueous Biphasic Systems with Ionic
Page 35 and 36: ILs + H2O Binary Systems __________
Page 41 and 42: Table 2. Experimental mole fraction
Page 49: 3. 3. QSPR Modelling of ILs + H2O B
Page 61 and 62: ILs + H2O + K3PO4 Ternary Systems _
Page 67: ILs + H2O + K3PO4 Ternary Systems _
Page 83: 5. 5. Final Remarks
Page 89 and 90: References ________________________
Page 95: 7. 7. List of Publications
Page 101 and 102: Appendix A ________________________
Page 111: Appendix B
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Aqueous Biphasic Systems with Ionic
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