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Experimental Methods, Results and Discussion distillation with more then 80 stages and fractional crystallization. Even so, Good et al. (1959) reported that after treatment with a neutral permanganate solution to remove olefinic impurities by oxidation followed by distillation in an efficient fractionating column and by silica gel percolation of selected fractions of distilled material, the purity of the best sample of perfluoromethylcyclohexane was only in the order of 98%. Table II.1. Purities and Origin of the Compounds Studied in This Work Compound Formula Origin Purity (%) Oxygen O2 Air Liquid 99.999 Carbon Dioxide CO2 Messer France 99.90 Perfluoro-n-hexane C6F14 Aldrich 99.11 Perfluoro-n-heptane C7F16 Aldrich 85 Perfluoro-n-octane C8F18 Aldrich 98.36 Perfluoro-n-nonane C9F20 Apollo Scientific 99.18 1Br-Perfluoro-n-octane 1Br-C8F17 ABCR 99.90 1H-Perfluoro-n-octane 1H-C8F17 Interchim 97.05 1H,8H-Perfluoro-n-octane 1H,8H-C8F16 Apollo Scientific 99.10 Perfluorodecalin C10F18 ABCR 99.88 Perfluorobenzene C6F6 Fluorochem 99.99 Perfluorotoluene C7F8 Apollo Scientific 99.80 Perfluoromethylcyclohexane C7F14 Apollo Scientific 99.98 n-Hexane C6H14 Aldrich 99.01 n-Heptane C7H16 Aldrich 99.34 n-Octane C8H18 Aldrich 99.33 n-Nonane C9H20 Aldrich 99.00 Crowder et al. (1967) stated that fluorocarbons are substances difficult to purify by fractional distillation because impurities in the form of fluorocarbon derivatives containing other elements, such as hydrogen, oxygen, and nitrogen, may form constant-boiling mixtures with the fluorocarbon or may boil at very nearly the same temperature. Also, structural isomers boil very close to one another, within a few degrees or tenths of degree. In their work, the authors used samples with purities approaching 100% only achieved using gas chromatography to purify the samples. - 25 -
Experimental Methods, Results and Discussion Nowadays, purities higher than 99% can be easily obtained for most of the perfluorocarbons. The main producers claim that the impurities present in the samples are essentially isomers of the main component. I.2. Density I.2.1. Bibliographic revision Density data can be measured both directly or indirectly using different methods. Between the most common methods for atmospheric pressure measurements are the volumetric and the hydrostatic weighting measurements (Pádua,1994). Volumetric methods are those that require the knowledge of the volume of the sample container. Its main disadvantage is that they are relative methods, which means that calibrations have to be performed along the experimental conditions to be studied, using calibrating fluids with densities similar to those to be measured. Volumetric measurements are usually performed using picnometers (Bauer et al., 1972), or densimeters with a vibrating tube with a U or V shape (Albert et al., 1984). Both techniques have a precision of 0.0005% but the accuracy obtained using the picnometer is higher (0.02%) than using the U vibrating tube (0.1%). However, the vibrating tube method is easy to operate and requires less amount of sample to be used. Hydrostatic weighting methods are the direct application of the Arquimedes principle, measuring the density of the fluid through the impulsion recorded by a solid body immersed in that fluid. There are essentially three hydrostatic weighting methods: the fluctuation technique, the magnetic levitation and the direct method. The fluctuation technique equilibrates a solid body immersed into the fluid in study for fixed conditions of temperature and pressure (Girard G., 1987), while the magnetic levitation or indirect method determines the impulsion applied to a solid body by measuring the force needed to levitate it, being this force related to the density of the fluid under study (Greer et al., 1974). The direct method measures the apparent weight of a float immersed into the fluid using an analytic balance. (Hales et al., 1983). The main advantage of this last method is that the volume problem is discarded being the measurements absolutes with no need of calibrations. The direct method, besides being simpler to apply, gives the best precision and accuracy (0.005% and 0.02% respectively against 0.01% and 0.1% obtained for the - 26 -
Page 1 and 2: Ana Maria Antunes Dias Universidade
Page 3 and 4: o júri presidente Prof. Dr. Joaqui
Page 5 and 6: palavras-chave resumo perfluoroalca
Page 7 and 8: Contents Notation List of Tables Li
Page 9 and 10: Notation Abbreviations AAD EoS LCST
Page 11 and 12: List of Tables Table I.1 Average Bo
Page 13 and 14: Table III.6 Adjusted Binary Paramet
Page 15 and 16: Figure II.9 Comparison between corr
Page 17 and 18: Figure III.8 Temperature-density di
Page 19 and 20: Figure III.25 Vapor-phase mole frac
Page 21 and 22: I.1. Fluorine Properties General In
Page 23 and 24: Table I.2. Physicochemical Properti
Page 25 and 26: General Introduction order to compa
Page 27 and 28: General Introduction the numerous a
Page 29 and 30: General Introduction carbon dioxide
Page 31 and 32: General Introduction animals. That
Page 33 and 34: General Introduction Table I.3. Lit
Page 35 and 36: References General Introduction Ban
Page 37 and 38: General Introduction Hildebrand, J.
Page 39 and 40: General Introduction Rowinsky EK. N
Page 41 and 42: II. Part EXPERIMENTAL METHODS, RESU
Page 43: Experimental Methods, Results and D
Page 47 and 48: 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 and 96:
II.6. Liquid - Liquid Equilibrium I
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Experimental Methods, Results and D
Page 99 and 100:
Page 101 and 102:
0 τ β Δ1 2Δ1 [ 1+ B τ + B τ +
Page 103 and 104:
References Experimental Methods, Re
Page 105 and 106:
Page 107 and 108:
Page 109 and 110:
Page 111 and 112:
III.1. Introduction Modeling Most c
Page 113 and 114:
Modeling The pioneering work of Wer
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III.2. Soft-SAFT Model Modeling A S
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Modeling The equation of state is w
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Chain Term Modeling Originally Wert
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Modeling The model is easily extend
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( ) ( ) ∑∑∑ 3 2 2 2 2 qq 32π
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Modeling HRT is a promising theory,
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( ρ) ρ , 0 ≤ ρ ( ρ) 2 Modelin
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III.3. Application to Pure Compound
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Modeling From the optimised paramet
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T / K 400 350 300 250 200 150 100 5
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ln Pvap 1.0E+01 1.0E+00 1.0E-01 1.0
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Modeling Table III.2. Absolute Aver
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Modeling The correlation coefficien
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Pvap (MPa) 4.00 3.50 3.00 2.50 2.00
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Modeling The mixture parameters a a
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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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