Kindly suggest some of the significant differences between the azeotropic and extractive distillation. Which one is generally preferred in the industries and why?
Azeotropic and extractive distillations are both methods of separating mixtures. Both of them also use a certain separating solvent to help in the process. The main difference between the two is in the process of separating the mixture. Azeotropic distillation forms an azeotrope right after combining the separation solvent. This azeotrope can be a complicated way of separating the mixture because it cannot be easily changed by just a simple distillation. In extractive distillation, a specific separation solvent is used in every mixture that should not form an azeotrope. In this way, extractive distillation is a better and easier method than the azeotropic distillation. But you need to bear in mind that if you have a mixture with very different volatilities, then the most effective separation method would be the azeotropic distillation.
Summary:
Azeotropic and extractive distillations are techniques used in the field of chemistry and engineering.
Azeotropic distillation is a process of distillation wherein you can add a certain component into the mixture to have a better separation process. Usually, the certain component added into the mixture is water or benzene, because these can help in increasing the volatility of a substance.
Extractive distillation is a distillation technique wherein the capability of mixing or miscibility, the component of being non-volatile, and even a high boiling point, could be the measurement of separating a mixture without even forming an azeotrope. This kind of method is usually used for mixtures with almost the same volatility.
The main difference between the two is in the process of separating the mixture. ... In extractive distillation, a specific separation solvent is used in every mixture that should not form an azeotrope. In this way, extractive distillation is a better and easier method than the azeotropic distillation.
The process of separating the mixture. Azeotropic distillation forms an azeotrope right after combining the separation solvent. This azeotrope can be a complicated way of separating the mixture because it cannot be easily changed by just a simple distillation. In extractive distillation, a specific separation solvent is used in every mixture that should not form an azeotrope. In this way, extractive distillation is a better and easier method than the azeotropic distillation. But you need to bear in mind that if you have a mixture with very different volatilities, then the most effective separation method would be the azeotropic distillation.
Azeotropic and extractive distillations are techniques used in the field of chemistry and engineering. Major industries, especially pharmaceuticals, are making use of these techniques to further improve their research.. Azeotropic and extractive distillations have some similarities but they also have distinct differences and these are observed on the processes. In chemistry, these processes are very essential in separating certain mixtures to form a new product. By comparing these two processes, you can see their differences.
1. Azeotropic and extractive distillations are techniques used in the field of chemistry and engineering.
2. Azeotropic distillation is a process of distillation wherein you can add a certain component into the mixture to have a better separation process. Usually, the certain component added into the mixture is water or benzene, because these can help in increasing the volatility of a substance.
3. Extractive distillation is a distillation technique wherein the capability of mixing or miscibility, the component of being non-volatile, and even a high boiling point, could be the measurement of separating a mixture without even forming an azeotrope. This kind of method is usually used for mixtures with almost the same volatility.
Azeotropic vs Extractive Distillation
Azeotropic and extractive distillations are techniques used in the field of chemistry and engineering. Major industries, especially pharmaceuticals, are making use of these techniques to further improve their research. Distillation is a very important process in separating certain components from the mixtureand is typically based on the volatility of the components in the mixture of the boiling liquid. Although these techniques are usually compared with each other, many chemical engineering students are still confused about the difference. Azeotropic and extractive distillations have some similarities but they also have distinct differences and these are observed on the processes. In chemistry, these processes are very essential in separating certain mixtures to form a new product. By comparing these two processes, you can see their differences.
What is azeotropic distillation?
Azeotropic distillation is a process of distillation wherein you can add certain components into the mixture to have a better separation process. Usually, the certain component added into the mixture is water or benzene, because these can help in increasing the volatility of a substance. By the way, volatility is the capacity of the substance to vaporize. In this process, the distillation process could form an azeotrope which can greatly help in the exact process of the separation because it won’t alter the components like a simple distillation would. Azeotropic distillation produces a heterogeneous mixture. In this method, an entrainer is used to trap particles in the current to separate the azeotrope.
What is extractive distillation?
Extractive distillation is a distillation technique wherein the capability of mixing or miscibility, the component of being non-volatile, and even a high boiling point, could be the measurement of separating a mixture without even forming an azeotrope. This kind of method is usually used for mixtures with almost the same volatility. In this method, a separation solvent will be used to interact with the mixture, thus helping the separation of the components. The good thing about this method is that by using the separation solvent, you can already easily separate the mixture without forming an azeotrope, which is common in other separation methods.
How do these two differ?
Azeotropic and extractive distillations are both methods of separating mixtures. Both of them also use a certain separating solvent to help in the process. The main difference between the two is in the process of separating the mixture. Azeotropic distillation forms an azeotrope right after combining the separation solvent. This azeotrope can be a complicated way of separating the mixture because it cannot be easily changed by just a simple distillation. In extractive distillation, a specific separation solvent is used in every mixture that should not form an azeotrope. In this way, extractive distillation is a better and easier method than the azeotropic distillation. But you need to bear in mind that if you have a mixture with very different volatilities, then the most effective separation method would be the azeotropic distillation.
Summary:
In azeotropic distillation a third component is added, which forms a volatile azetropic mixture with one of the two components which is drawn from top of the distillation tower. The component forming the azeotrope is not necessarily the more volatile, but it must be immiscible at low temperature with the other component of the azeotrope, so that, when coold down, the azeotrope splits completely in its components. Typical case: the azeotropic distillation with cyclohexane of the ethanal-water mixtures. Ethanol is more volatile than water, but cyclohexane-water azeotrope is more volatile than ethanol. So ethanol is the btm product and the water-cyclohexane azeotrope the top one, which is then cooled down and it splits almost completely into water and cyclohexanol (the traces left of cyclohexane in water can be eliminated by a weak stripping).
Extractive distillation is realized by adding a third component which alters the volatility of one of the two components and increases their relative volatility. E.g. for the ethanol-water case ethylene glycol decreases water volatility because of its affinity for it. As a result the ethanol water relative volatility is increased and distillation is made easier, without the presence of an ethanol-water azeotrope, i.e. with the possibility of attaining highly pure ethanol. A drawbak of this method is that the water-glycol btm product has to be separated in a second tower to recover glycol.
The azeotropic route is more favourable in that case.
Azeotropic distillation has several choices, like vacuum columns and pressure swing. Extractive distillation uses two liquids and usually two or more columns, making the equipment large and consuming much energy. Azeotropes can be broken in the extractive process, but newer methods like pervaporation tend to be more economical.
Extractive distillation is the term used when a high boiling solvent is used as a seperating agent. The key to the definition of extractive distillation is that the solvent or entrainer is the highest boiling component and has a boiling point much higher than the other components in the feed mixture. Wether azeotropes is formed or not in the system is not a criteria for definition. I would also like you to see if the definition involves the specification of number of feeds. I think if you have two feeds in the column with the upper feed being relatively pure solvent it is definitely extractive distillation (but I can't seem to clearly remember this). Please reffer Seperation Princliples by Seader, it is an excellent book and will clear your doubts well.
Both processes involve the addition of a new material, the solvent, to the mixture. The solvent is chosen so as to increase the relative volatility of the components to be separated. Azeotropic distillation is a process of distillation wherein you can add a certain component into the mixture to have a better separation process. Usually, the certain component added into the mixture is water or benzene, because these can help in increasing the volatility of a substance.
Azeotropic distillation is accomplished by adding to the liquid phase, a volatile third component (entrainer), which changes the volatility of one of the two components more than the other so that the components are separated by distillation. Extraction Distillation is a distillation technique wherein the capability of mixing or miscibility, the component of being non-volatile, and even a high boiling point, could be the measurement of separating a mixture without even forming an azeotrope. This kind of method is usually used for mixtures with almost the same volatility. In other word; if the volatility difference is so small that an adequate separation cannot be made, it may be possible to increase the volatility difference by the addition of an extraneous material that can be separated later; this process is known as extractive distillation if the added material is relatively nonvolatile and leaves the column with the residue.
As in the case of azeotropic distillation, an extraneous material is added to the mixture in the case of extractive distillation. However, the function of this material, called an extractive agent or simply a solvent, is different. Solvent need to be vaporized. As in the case of azeotropic distillation, there is the problem of separating the solvent from the product, but for extractive distillation the problem is much simpler, since the solvent is normally quite high boiling, beyond the range of azeotrope formation, and simple distillation usually is sufficient to separate the solvent for reuse. During extractive distillation, the solvent is generally added near the top of the column, and because it has a low volatility it is withdrawn with the product at the bottom. Less solvent is required. The use of the solvent with the highest relative volatility (or selectivity) will always give the lowest total annual cost (TAC) of the extractive distillation process. In azeotropic distillation, the solvent is withdrawn as an azeotrope with one or more of the components to be separated— usually in the overhead product
The main difference between the two is in the process of separating the mixture. Azeotropic distillation forms an azeotrope right after combining the separation solvent. This azeotrope can be a complicated way of separating the mixture because it cannot be easily changed by just a simple distillation. In extractive distillation, a specific separation solvent is used in every mixture that should not form an azeotrope. In this way, extractive distillation is a
better and easier method than the azeotropic distillation. But you need to bear in mind that if you have a mixture with very different volatilities, then the most effective separation method would be the azeotropic distillation.
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