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Comparison of three solvents for extractive distillation of ethanol and water system
Published in Alka Mahajan, Parul Patel, Priyanka Sharma, Technologies for Sustainable Development, 2020
Tushar Perkar, Naitik Chokshi, Milind Joshipura*
Distillation is one of the prominent techniques used in various chemical industries for the separation of two or more components. Distillation column contributes to more than 50% of the plant’s energy consumption. Therefore, it is very important to appropriately design, fabricate and run the distillation column. Simple distillation column is able to separate all mixtures except azeotropic mixtures. In an azeotrope, the constitution of its liquid is the same as the vapor, and hence cannot be separated by simple distillation processes. Various methods have been devised to separate these constant boiling azeotropes, such as extractive distillation (ED), pressure- swing distillation, liquid-liquid extraction and so on. Amongst these, ED is most widely used in the industry. In ED, solvent is added to the mixture which has a higher affinity with one of the components in the azeotrope and thus facilitates the separation of the two compounds forming the azeotrope. Also, the solvent feed enters the distillation column at a stage different than that of the azeotropic feed. In ED, one of the components appears in the distillate and the other component along with the entrainer gets separated in the bottom product. The bottom product is fed into another column, known as the entrainer recovery column, where the entrainer and the component gets separated by simple distillation and thus the azeotrope is broken and the components get separated.
Aldehydes and Ketones. Acyl Addition Reactions
Published in Michael B. Smith, A Q&A Approach to Organic Chemistry, 2020
An azeotrope is a constant boiling mixture of liquids because the vapor has the same composition as the liquid mixture. An example is water, ethanol, and benzene What is the azeotrope of ethanol and water?
Critical Cleaning of Advanced Lubricants from Surfaces
Published in Leslie R. Rudnick, Synthetics, Mineral Oils, and Bio-Based Lubricants, 2020
Ronald L. Shubkin, Barbara F. Kanegsberg, Ed Kanegsberg
An important thing to note about blends is that some are azeotropes and some are not. An azeotrope is a blend where the relative concentrations of the components are the same in the boiling liquid and the vapor. When two or more compounds are blended in the correct proportions to form an azeotrope, the resulting blend can be distilled at a constant temperature and the relative concentrations in the distillate will be the same as in the distillation pot. In an operation using a vapor degreaser, it is important to use an azeotropic blend. If a non-azeotropic blend is used, the vapor degreaser will act like a distillation unit. The higher boiling component will be concentrated in the boil-up sump while the lower boiling solvent will concentrate in the rinse sump. A number of products sold for use in vapor degreasers are termed “near azeotropes” or “azeotrope-like”. This means that the relative concentrations in the distillate are close but not exactly the same as in the distillation pot and over time, the liquid in the sumps will change over time. Even with true azeotropes, it is important to keep in mind that a mixture of two or more chemicals is an azeotrope only within a limited temperature range and that the azeotropic conditions can change if soil loading – e.g. soils that are removed from surfaces by cleaning – occurs and become a significant portion of the boil-up sump. In cold cleaning operations, hand wipes, and aerosols, azeotropic performance is not needed.
Pressure-swing distillation process for separating ternary azeotropic mixture of acidic aqueous solution
Published in Chemical Engineering Communications, 2022
B. Mahida, H. Benyounes, S. Jin, W. Shen
However, the experimental studies of vapor-liquid equilibrium for the ternary system AA/FA/W (Conti et al. 1960; Kushner et al. 1966; Wisniak and Tamir 1977) show that the region of the ternary azeotrope shifts inside the ternary diagram, confirming the pressure sensitive ternary azeotrope. Furthermore, since the binary and ternary azeotropes in AA/FA/W mixture are pressure sensitive, the PSD seems to be possible. Many mixtures form an azeotrope whose position can be shifted substantially by changing the system pressure; thus a pressure sensitive azeotrope. Indeed, at some pressure, the azeotrope may even disappear allowing separation azeotropic mixtures by PSD, as already used to separate azeotropic mixtures (Abu-Eishah and Luyben 1985; Chang and Shih 1989; Phimister and Seider 2000).
Multicomponent gas transport in a Stefan diffusion column containing an azeotropic liquid mixture of acetone-n-hexane
Published in Chemical Engineering Communications, 2022
Isamaris Moreno, Marimar Moreno, Carlos A. Ramírez
Who was John Wade and why was his unfortunate demise significant to the present work? At the time of his death, he was Lecturer and Head, Department of Chemistry, Guy’s Hospital, London. One of his last papers was titled “Influence of water on the boiling point of ethyl alcohol at pressures above and below the atmospheric pressure” (Wade and Merriman 1911). Since ethyl alcohol and water form a minimum-boiling point mixture at atmospheric pressure (boiling point = 351.25 K, water mole fraction = 0.103; Lide 2004), Wade coined the term “azeotrope” to refer concisely to both minimum-boiling point and maximum-boiling point mixtures. These do not change composition upon evaporation at constant temperature and pressure. The Wade and Merriman (1911) study motivated our group to place a binary liquid azeotrope at the bottom of a Stefan column to determine the gas diffusivity of the solvents by integrating the Maxwell-Stefan equations for multicomponent mass transport. The liquid azeotrope would guarantee invariant mole fractions for both species at the liquid-gas interface. This report represents the first such application in the Stefan column, which has a meritorious history in the field of mass transfer leading to the determination of binary gas diffusivities.
Dehydration – purification of aqueous ethyl alcohol by adsorption over molecular sieves: continuous operation
Published in Journal of the Chinese Institute of Engineers, 2021
Pooja Sanap, Akash Shetty, Yogesh Mahajan
Generally, fermentation is known to produce a dilute aqueous mixture of ethanol (<20 mass %, Bothast and Schlicher 2005). Mostly, fermentation broth contains a large amount of water, an appreciable amount of the desired product and a small to negligible amount of several impurities. Ethanol forms azeotrope with water (95.63 mass % ethanol at 351 K, Gmehling and Onken 1991). By using distillation, the concentration of dilute aqueous ethanol can be increased to higher values (85– 90 mass %) or even to its azeotropic composition. The higher concentration and azeotropic ethanol can be used in medicines and also as solvents, e.g. in perfumery products. Almost anhydrous ethanol (~99.5 mass % or more) finds use in beverages and as fuel additive. Many methods can be used for this final separation: use of membranes like in pervaporation, liquid–liquid extraction and use of advanced distillation methods like azeotropic, extractive and pressure swing distillation.