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Distillation, also classical distillation, is the process of separating the component substances of a liquid mixture of two or more chemically discrete substances; the separation process is realized by way of the selective boiling of the mixture and the condensation of the vapors in a still.
An azeotrope or a constant heating point mixture is a mixture of two or more liquids whose proportions cannot be changed by simple distillation. This happens because when an azeotrope is boiled, the vapour has the same proportions of constituents as the unboiled mixture. Knowing an azeotrope's behavior is important for distillation.
Fractional distillation is the separation of a mixture into its component parts, or fractions. Chemical compounds are separated by heating them to a temperature at which one or more fractions of the mixture will vaporize. It uses distillation to fractionate. Generally the component parts have boiling points that differ by less than 25 °C (45 °F) from each other under a pressure of one atmosphere. If the difference in boiling points is greater than 25 °C, a simple distillation is typically used.
In chemistry, azeotropic distillation is any of a range of techniques used to break an azeotrope in distillation. In chemical engineering, azeotropic distillation usually refers to the specific technique of adding another component to generate a new, lower-boiling azeotrope that is heterogeneous, such as the example below with the addition of benzene to water and ethanol.
Extractive distillation is defined as distillation in the presence of a miscible, high-boiling, relatively non-volatile component, the solvent, that forms no azeotrope with the other components in the mixture. The method is used for mixtures having a low value of relative volatility, nearing unity. Such mixtures cannot be separated by simple distillation, because the volatility of the two components in the mixture is nearly the same, causing them to evaporate at nearly the same temperature at a similar rate, making normal distillation impractical.
This page provides supplementary chemical data on ethanol.
A zeotropicmixture, or non-azeotropic mixture, is a mixture with liquid components that have different boiling points. For example, nitrogen, methane, ethane, propane, and isobutane constitute a zeotropic mixture. Individual substances within the mixture do not evaporate or condense at the same temperature as one substance. In other words, the mixture has a temperature glide, as the phase change occurs in a temperature range of about four to seven degrees Celsius, rather than at a constant temperature. On temperature-composition graphs, this temperature glide can be seen as the temperature difference between the bubble point and dew point. For zeotropic mixtures, the temperatures on the bubble (boiling) curve are between the individual component's boiling temperatures. When a zeotropic mixture is boiled or condensed, the composition of the liquid and the vapor changes according to the mixtures's temperature-composition diagram.
Batch distillation refers to the use of distillation in batches, meaning that a mixture is distilled to separate it into its component fractions before the distillation still is again charged with more mixture and the process is repeated. This is in contrast with continuous distillation where the feedstock is added and the distillate drawn off without interruption. Batch distillation has always been an important part of the production of seasonal, or low capacity and high-purity chemicals. It is a very frequent separation process in the pharmaceutical industry.
A heteroazeotrope is an azeotrope where the vapour phase coexists with two liquid phases. Sketch of a T-x/y equilibrium curve of a typical heteroazeotropic mixture
The McCabe–Thiele method is a technique that is commonly employed in the field of chemical engineering to model the separation of two substances by a distillation column. It uses the fact that the composition at each theoretical tray is completely determined by the mole fraction of one of the two components. This method is based on the assumptions that the distillation column is isobaric—i.e the pressure remains constant—and that the flow rates of liquid and vapor do not change throughout the column. The assumption of constant molar overflow requires that:
In thermodynamics and chemical engineering, the vapor–liquid equilibrium (VLE) describes the distribution of a chemical species between the vapor phase and a liquid phase.
This page provides supplementary chemical data on benzene.
This page provides supplementary chemical data on p-xylene.
This page provides supplementary chemical data on ethylene glycol.
This page provides supplementary chemical data on acetonitrile.
This page provides supplementary chemical data on diethyl ether.
This page provides supplementary chemical data on carbon disulfide.
This page provides supplementary chemical data on o-Xylene.
This page provides supplementary chemical data on m-Xylene.
A residue curve describes the change in the composition of the liquid phase of a chemical mixture during continuous evaporation at the condition of vapor–liquid equilibrium. Multiple residue curves for a single system are called residue curves map.
References
- ↑ Lange's Handbook of Chemistry, 10th ed. pp. 1496–1505
- ↑ CRC Handbook of Chemistry and Physics, 44th ed. pp. 2143–2184
- 1 2 3 4 5 Lee H. Horsley, ed. (1 June 1973). Azeotropic Data—III. Advances in Chemistry Series No. 166. Vol. 116. American Chemical Society. doi:10.1021/ba-1973-0116. ISBN 9780841201668.
- ↑ "Azeotrope Databank".
- 1 2 3 4 5 "What is an Azeotrope?". B/R Corporation. Archived from the original on 24 April 2007. Retrieved 24 March 2007.
- 1 2 3 4 5 6 7 8 9 10 11 12 John Durkee (November 2000). "Binary Organic Azeotropes Useful for Solvent Cleaning" (PDF). metalfinishing.com. Retrieved 13 February 2011.[ permanent dead link ]
- 1 2 Hilmen, Eva-Katrine (November 2000). "Separation of Azeotropic Mixtures: Tools for Analysis and Studies on Batch Distillation Operation" (PDF). Norwegian University of Science and Technology, dept. of Chemical Engineering. Archived from the original (PDF) on 5 September 2004. Retrieved 24 March 2007.
- ↑ Composition of Vapors from Boiling Binary Solutions J. J. Conti, D. F. Othmer, Roger Gilmont. J. Chem. Eng. Data, 1960, 5 (3), pp. 301–307 doi : 10.1021/je60007a019
- ↑ US4826576A,Berg, Lloyd&Yeh, An-I.,"Separation of isopropyl acetate from isopropanol by extractive distillation",issued 1989-05-02
- 1 2 3 "Zeon Corporation" (PDF). Archived from the original (PDF) on 22 July 2011. Retrieved 5 August 2024.
- ↑ "Modeling and optimization of pressure distillation to achieve pharma-grade THF".
- 1 2 3 4 5 6 "MeTHF training presentation" (PDF). Retrieved 31 July 2024.
- ↑ Merck Index of Chemicals and Drugs, 9th ed. monograph 4653
- 1 2 Reinders, W.; de Minjer, C. H. (3 September 2010). "Vapour-liquid equilibria in ternary systems. V. The system water-formic acid-metaxylene". Recueil des Travaux Chimiques des Pays-Bas. 66 (9): 564–572. doi:10.1002/recl.19470660905.
- 1 2 3 4 5 6 Ponton, Jack (September 2001). "Azeotrope Databank". The Edinburgh Collection of Open Software for Simulation and Education, University of Edinburgh. Archived from the original (Queriable database) on 24 April 2007. Retrieved 24 March 2007.
- 1 2 3 "Binary Vapor-Liquid Equilibrium Data" (Queriable database). Chemical Engineering Research Information Center.
- ↑ Rumble, John (2020). CRC Handbook of Chemistry and Physics (101 ed.). Taylor & Francis Group.
- 1 2 "Tetrahydrofuran (THF) Storage and Handling" (PDF). BASF. Archived from the original (PDF) on 8 May 2005. Retrieved 24 May 2007.
- ↑ CRC Handbook of Chemistry and Physics (90th ed.).
- ↑ US US2530325,Carl S Carlson,"Azeotropic distillation of mesitylene from isophorone",published 1950-11-14,issued 1950-11-14
- ↑ "1,2-Propanediol". ChemIndustry.ru. Archived from the original on 21 December 2007. Retrieved 28 December 2007.