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

More documents

Recommendations

Info

Aqueous Biphasic Systems with Ionic Liquids _________________________________________________________________________ 40 0. 5 BX T CX 3 BX 0. 5 CX 3 YT Aexp T (6) YB Aexp B B (7) Y 1 ' Y M YT ' ' X M X T ' ' B 1 ' X B The subscript letters T, B and M represent respectively the top, the bottom and the mixture phase. The parameter α' is the ratio between the top mass and the total mass of the mixture. The solution of the referred system gives the concentration of the IL and salt in the top and bottom phases. For calculation of the tie-line length (TLL) was used Eq. 10 TLL 2 2 ( XT X B) ( YT YB ) (10) 4.2.3. Partitioning of L-tryptophan The partition coefficients of L-tryptophan, KTrp, are defined as the ratio of the concentration of L-tryptophan in the IL and in the K3PO4 aqueous-rich phases and as described by Eq. 11, 3 4 PO K Trp IL K (11) Trp Trp where [Trp]IL and [Trp]K 3 PO 4 are the concentration of L-tryptophan in the IL and in the K3PO4 aqueous-rich phases, respectively. A mixture in the biphasic region was selected and used to evaluate the L-tryptophan partitioning. For this purpose aqueous solutions of L-tryptophan with a concentration of approximately 0.78 g·dm -3 were used. The biphasic solution was left to equilibrate for 12 h (a time period established in previous optimizing experiments) to achieve a <strong>com</strong>plete L- tryptophan partitioning between the two phases. The aminoacid quantification, in both phases, was carried by UV spectroscopy using a SHIMADZU UV-1700, Pharma-Spec Spectrometer, at a wavelength of 279 nm and using calibration curves previously established (cf. Appendix B). Moreover, both phases were weighted and the corresponding TLs obtained as previously described. (8) (9)
ILs + H2O + K3PO4 Ternary Systems _________________________________________________________________________ 4.3. Results and Discussion 4.3.1. Phase Diagrams and Tie-Lines Since ILs are ionic by nature, the IL-based ABS are more <strong>com</strong>plex than typical polyethylene glycol-based ABS due to the possibility of ion exchange and/or ion-pairing between both salt phases. Bridges et al. 58 have shown that there is ion partition between both phases yet maintaining electroneutrality. However, the overall deviations observed are small enough to be considered as a source of error in the cloud point titration (as determined by radioanalitycal results) and thus yielding a satisfactory representation of the ions concentration present at any TL. The experimental phase diagrams at 298 K and at atmospheric pressure for each IL + K3PO4 + H2O system are shown in Figure 18, Figure 19, 21 and Figure 22 in molality units for a detailed understanding of the ILs impact on the ABS formation (cf. Appendix B with the experimental weight fraction data). Figure 18 and 19 show the influence of the cation while Figures 21 and 22 show the anion influence. Figure 18 shows the binodal curve for the ILs [amim][Cl], [OHC2mim][Cl], [C7H7mim][Cl], [C6mim][Cl], [C4mim][Cl], [C2mim][Cl] and [C1mim][Cl]. 41
Page 1:
Catarina Maia Seco Seiça Neves Uni
Page 5:
Ao meu Pai e ao meu Avô…
Page 9:
agradecimentos Gostaria de começar
Page 13:
keywords abstract Ionic liquids, wa
Page 16 and 17: 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 65: 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
Page 116 and 117:
Aqueous Biphasic Systems with Ionic
Page 118 and 119:
Page 120 and 121:
Page 122 and 123:
Page 124 and 125:
Page 126 and 127:
Page 128 and 129:
Page 130 and 131:
Page 132 and 133:
Page 134 and 135:
Page 136 and 137:
Page 138 and 139:
Page 140 and 141:
Page 142 and 143:
Page 144 and 145:
Page 146 and 147:
Page 148 and 149:
show all

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

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?