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Modeling III.4.2. Solubility of Rare Gases in Perfluoroalkanes at Atmospheric Pressure It was shown that to correctly describe experimental data relating the solubility of oxygen in perfluoroalkanes, a special interaction between the oxygen molecule and the fluorinated molecules had to be considered in some cases. It would be interesting to test the model for the same solvents but with a solute where no interaction could be possible, as is the case of rare gases, in order to confirm that the inaccuracy of the soft-SAFT model without cross-association in describing some O2/perfluoroalkanes systems is due to an abnormal behaviour of these mixtures instead of a failure of the model. Data for the solubility of xenon and radon in perfluoroalkanes were measured by Kennan and Pollack (1988) and Lewis et al. (1987), respectively. In the case of the solubility of xenon, besides the practical applications that xenon’s solubility can find in nuclear medicine and for studies of general anesthesia and nuclear reactor safety, the authors also wanted to study the solubility of an inert solute in perfluoroalkanes to compare with previous results they obtained for the solubility in the corresponding alkanes and take conclusions about the solubilization process in both cases. In the case of radon, the authors where looking for a good solvent to help in the removal of radon from the ventilation streams in uranium mines to meet radiation exposure limits. They suggested that conventional packed bed scrubbers could be used if an appropriate nonaqueous solvent could be identified. The characteristics of such a solvent include high radon solubility, low vapor pressure at operating temperature, nonflammable and non-toxic, chemically unreactive and with low viscosity. As perfluorinated compounds present almost all the right properties required for the wanted solvent, they decided to study the solubility of radon in several perfluoroalkanes. In both works solubility data were presented in terms of Ostwald coefficient and solute molar fraction at a partial pressure of the gas equal to 1 atm. The equilibrium molar fractions of the liquid and gaseous phase where calculated according to the procedure for data reduction presented previously on Part II. Previous studies have been done on the modelling of the solubility data of xenon in perfluoroalkanes, particularly perfluoro-n-hexane (Bonifácio et al., 2002). The authors used both molecular simulation and the SAFT-VR EoS to describe experimental data. They observed that in both cases a binary interaction parameter had to be introduced in order to reproduce the experimental results. They were expecting this behaviour since in a - 131 -
Modeling previous work, dealing with the phase diagram of xenon in lighter alkanes (C1 to C4) and perfluoroalkanes (C1 to C2), also using the SAFT-VR, they showed that while the behaviour of xenon correlated strongly with that of the n-alkanes (the experimental phase diagrams and excess volumes could be described accurately using simple Lorentz- Berthelot combining rules to determine the cross interaction parameters), for xenon in nperfluoroalkanes the existing experimental data could only be reproduced by introducing a binary interaction parameter (Filipe et al., 2000 and McCabe et al., 2001). The energetic binary interaction parameter used by the authors was the same that they used in an earlier study of alkane + perfluoroalkanes binary mixtures (McCabe et al., 2001), equal to 0.92. They stated that although this was not the best value and a slight improvement would be possible if the parameter were fitted to the specific system, they preferred to use the parameters in a transferable way giving importance to the predictive capability of the equation instead of look for the accuracy of the results given by the model. In this work a similar study were carried out using the soft-SAFT EoS to describe solubility data for xenon and radon in perfluoroalkanes. Both solutes and solvents were modelled as non associating molecules and any kind of interaction was admitted between them. As in the work of Filipe et al. (2000) only the energetic parameter had to be included to correctly describe experimental data. It was adjusted for each mixture and is listed in Table III.6. Table III.6. Adjusted Binary Parameters for the Solubility of Xenon and Radon in Fluorinated Compounds and AADs of the Calculations by the Soft-SAFT EOS with Respect to Experimental Data Solvent η ξ AAD (%) C6F14 Xenon 1 0.870 3 C7F16 1 0.860 2 C8F18 1 Radon 0.860 1 C6F14 1 0.825 7 C8F18 1 0.825 4 - 132 -
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Ana Maria Antunes Dias Universidade
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o júri presidente Prof. Dr. Joaqui
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palavras-chave resumo perfluoroalca
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Contents Notation List of Tables Li
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Notation Abbreviations AAD EoS LCST
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List of Tables Table I.1 Average Bo
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Table III.6 Adjusted Binary Paramet
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Figure II.9 Comparison between corr
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Figure III.8 Temperature-density di
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Figure III.25 Vapor-phase mole frac
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I.1. Fluorine Properties General In
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Table I.2. Physicochemical Properti
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General Introduction order to compa
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General Introduction the numerous a
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General Introduction carbon dioxide
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General Introduction animals. That
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General Introduction Table I.3. Lit
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References General Introduction Ban
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General Introduction Hildebrand, J.
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General Introduction Rowinsky EK. N
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II. Part EXPERIMENTAL METHODS, RESU
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Experimental Methods, Results and D
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Table II.3. (continued) T K ρexp g
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ρ / g.cm-3 1.750 1.730 1.710 1.690
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I. 3. Vapour pressure I.3.1. Biblio
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I.3.2. Apparatus and Procedure Expe
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I.3.3. Experimental Results and Dis
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Table II.8. (continued) T K Pexp kP
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ΔH vap = TΔS vap 2⎛ d ln P ⎞
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I.4. Solubility at atmospheric pres
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x2 (T,P2) 7.0E-03 6.0E-03 5.0E-03 4
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L 2,1 0.70 0.60 0.50 0.40 0.30 285
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P / MPa 6 5 4 3 2 1 0 P / MPa 14 12
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II.6. Liquid - Liquid Equilibrium I
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Page 99 and 100: Experimental Methods, Results and D
Page 101 and 102: 0 τ β Δ1 2Δ1 [ 1+ B τ + B τ +
Page 103 and 104: References Experimental Methods, Re
Page 111 and 112: III.1. Introduction Modeling Most c
Page 113 and 114: Modeling The pioneering work of Wer
Page 115 and 116: III.2. Soft-SAFT Model Modeling A S
Page 117 and 118: Modeling The equation of state is w
Page 119 and 120: Chain Term Modeling Originally Wert
Page 121 and 122: Modeling The model is easily extend
Page 123 and 124: ( ) ( ) ∑∑∑ 3 2 2 2 2 qq 32π
Page 125 and 126: Modeling HRT is a promising theory,
Page 127 and 128: ( ρ) ρ , 0 ≤ ρ ( ρ) 2 Modelin
Page 129 and 130: III.3. Application to Pure Compound
Page 131 and 132: Modeling From the optimised paramet
Page 133 and 134: T / K 400 350 300 250 200 150 100 5
Page 135 and 136: ln Pvap 1.0E+01 1.0E+00 1.0E-01 1.0
Page 137 and 138: Modeling Table III.2. Absolute Aver
Page 139 and 140: Modeling The correlation coefficien
Page 141 and 142: Pvap (MPa) 4.00 3.50 3.00 2.50 2.00
Page 143 and 144: Modeling The mixture parameters a a
Page 145 and 146: Modeling the assumptions made by th
Page 147 and 148: Modeling between oxygen and perfluo
Page 149: xSolute 5.5E-03 5.0E-03 4.5E-03 4.0
Page 153 and 154: Modeling These results confirm that
Page 155 and 156: Modeling CO2 binary mixtures using
Page 157 and 158: Modeling average deviation (AAD) be
Page 159 and 160: P / MPa 14 12 10 8 6 4 2 0 0 0.2 0.
Page 161 and 162: Modeling Figures III.16, III.17 and
Page 163 and 164: Modeling calculations from the orig
Page 165 and 166: Table III.9. References for VLE exp
Page 167 and 168: P / MPa 20 18 16 14 12 10 8 6 4 2 0
Page 169 and 170: Modeling Finally, Figure III.24 pre
Page 171 and 172: III.4.4. VLE and LLE of Alkane and
Page 173 and 174: Modeling number of perfluro-n-alkan
Page 175 and 176: y C6F14 1.0 0.8 0.6 0.4 0.2 0.0 0.0
Page 177 and 178: P / MPa 0.08 0.07 0.06 0.05 0.04 0.
Page 179 and 180: P / MPa 0.12 0.10 0.08 0.06 0.04 0.
Page 181 and 182: Modeling approach based on the meth
Page 183 and 184: Modeling Blas, F. J.; Vega, L. F.,
Page 185 and 186: DIPPR, Thermophysical Properties Da
Page 187 and 188: Modeling Hildebrand, J. H.; Fisher,
Page 189 and 190: Modeling McCabe, C.; Jackson, SAFT-
Page 191 and 192: Modeling Poling, B.; Prauznitz, J.;
Page 193 and 194: Modeling Wertheim, M. S., Fluids wi
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