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Experimental Methods, Results and Discussion equilibration and phase separation periods are required in order to obtain accurate measurements. Also, care must be taken to guarantee that a complete separation of the phases was achieved before sampling. The aim of this work is to contribute with new reliable experimental data for perfluoroalkane + alkane mixtures. A bibliographic revision on experimental data relating these systems is compiled in Table II.19. It resumes the methods and experimental conditions used to perform liquid-liquid solubility measurements for mixtures of linear, cyclic and aromatic alkanes and perfluoroalkanes that are liquid at ambient temperature. Table II.19. Compilation of the References Reporting Experimental Liquid-Liquid Solubility Data for Perfluoroalkane + Alkane Systems System Method C7F14 + C6H6 C7F14 + C7H8 C7F16 + C6H6 C7F16 + C7H16 Synthetic Synthetic T range (K) 308 - 359 316 - 362 330 - 387 300 - 323 P range (MPa) Reference 0.1 Hildebrand and Cochran (1949) 0.1 Hildebrand et al. (1950) C7F16 + C8H18 Synthetic 300 - 341 0.1 Campbell and Hickman (1953) C7F16 + C6H14 Synthetic 283 - 302 0.1 Hickman (1955) C6F14 + C6H14 Synthetic 250 - 294 0.1 Bedford and Dunlap (1958) C6F14 + C6H14 290 - 295 C6F14 + C7H16 Synthetic 300 - 315 286 - 325 0.1 Duce et al. (2002) C6F14 + C8H18 II.6.2. Apparatus and procedure In this work, liquid-liquid equilibria (LLE) of binary mixtures of perfluoro-noctane plus alkanes, n-CnH2n+2 (n = 6 - 9), were measured, using the synthetic method, by turbidimetry at atmospheric pressure, and using a light scattering technique for measurements at pressures up to 1500 bar. At atmospheric pressure, different samples of n-perfluorooctane + n-alkane were prepared by weighting and sealed in an ampoule with a magnetic stirrer. The pure compounds were kept into molecular sieves to avoid moisture contamination. The ampoules were sealed frozen in liquid nitrogen to avoid changes in the composition of the samples. The ampoules with mixtures at different compositions were then placed in a thermostatic bath where a calibrated Pt 100 temperature sensor with an uncertainty of - 77 -
Experimental Methods, Results and Discussion 0.05K is immersed. The cloud points were determined by visual observation by heating the samples until a homogeneous phase is obtained followed by slow cooling of the mixtures until phase separation is observed. The accurate detection of cloud points at higher pressures was performed with a He-Ne laser light scattering cell. The apparatus, as well as the methodology used for the determination of phase transitions, have been described in detail elsewhere (Sousa and Rebelo, 2000). The apparatus is easy, fast and safe to operate since both temperature and pressure are computer controlled and it is fully automated (including data acquisition and treatment). The solution is contained in a high-pressure glass capillary (or sapphire capillary) and the phase transition can be induced either by changing the cell temperature (at constant pressure) or by changing pressure (at constant temperature), or by any other combination of these changes. The temperature accuracy is typically ± 0.01 K (240 < T/K < 520). The pressure accuracy is ± 0.01 MPa for pressures ranging from (0 to 7) MPa (glass cell) or 35 MPa (sapphire cell), although the final pressure accuracy of each cloud point determination is somewhat poorer. During an experiment, the cell containing the solution of a known composition is immersed in the high precision oil (or water) bath at a given temperature and pressure, in the homogeneous one-phase region. The top cap of the capillary cell is fitted to an HPLC high-pressure valve, which allows the cell to be filled with solvent using syringes. Stirring is accomplished by using a magnetic stirrer, which is turned off during the data acquisition in order to avoid shear effects. By changing temperature and/or pressure the phase transition is induced. Light from a He-Ne LASER passes across the solution contained in the cell. Scattered and transmitted light intensities are converted into electrical signals by two photo-detectors. These signals are measured with a digital multimeter equipped with an automatic channel scanner. Pressure is generated by a high pressure screw injector, coupled to a stepper motor, and controlled by a control box and a personal computer. Pressure is measured by a digital manometer and by the multimeter. Temperature is measured with a platinum resistance thermometer linked to a 6 1/2 digits multimeter. Both multimeters have IEEE-488 interfaces, which allow the computer data aquision. Cloud-points are detected when there is a sudden increase in scattered light from the He-Ne LASER accompanied by a sudden decrease in transmitted light exiting the cell. - 78 -
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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
Page 45 and 46: Experimental Methods, Results and D
Page 49 and 50: Table II.3. (continued) T K ρexp g
Page 51 and 52: ρ / g.cm-3 1.750 1.730 1.710 1.690
Page 55 and 56: I. 3. Vapour pressure I.3.1. Biblio
Page 57 and 58: I.3.2. Apparatus and Procedure Expe
Page 59 and 60: I.3.3. Experimental Results and Dis
Page 63 and 64: Table II.8. (continued) T K Pexp kP
Page 67 and 68: ΔH vap = TΔS vap 2⎛ d ln P ⎞
Page 69 and 70: I.4. Solubility at atmospheric pres
Page 79 and 80: x2 (T,P2) 7.0E-03 6.0E-03 5.0E-03 4
Page 81 and 82: L 2,1 0.70 0.60 0.50 0.40 0.30 285
Page 93 and 94: P / MPa 6 5 4 3 2 1 0 P / MPa 14 12
Page 95: II.6. Liquid - Liquid Equilibrium I
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
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Modeling between oxygen and perfluo
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xSolute 5.5E-03 5.0E-03 4.5E-03 4.0
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Modeling previous work, dealing wit
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Modeling These results confirm that
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Modeling CO2 binary mixtures using
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Modeling average deviation (AAD) be
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P / MPa 14 12 10 8 6 4 2 0 0 0.2 0.
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Modeling Figures III.16, III.17 and
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Modeling calculations from the orig
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Table III.9. References for VLE exp
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P / MPa 20 18 16 14 12 10 8 6 4 2 0
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Modeling Finally, Figure III.24 pre
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III.4.4. VLE and LLE of Alkane and
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Modeling number of perfluro-n-alkan
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y C6F14 1.0 0.8 0.6 0.4 0.2 0.0 0.0
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P / MPa 0.08 0.07 0.06 0.05 0.04 0.
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P / MPa 0.12 0.10 0.08 0.06 0.04 0.
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Modeling approach based on the meth
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Modeling Blas, F. J.; Vega, L. F.,
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DIPPR, Thermophysical Properties Da
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Modeling Hildebrand, J. H.; Fisher,
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Modeling McCabe, C.; Jackson, SAFT-
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Modeling Poling, B.; Prauznitz, J.;
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Modeling Wertheim, M. S., Fluids wi
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