Search results
Results From The WOW.Com Content Network
For instance, in a distillation of ethanol and water, water will boil out of the remaining ethanol, rather than the ethanol out of the water as at lower concentrations. Overall the pressure-swing distillation is a very robust and not so highly sophisticated method compared to multi component distillation or membrane processes, but the energy ...
Distillation, widely used in petroleum refining and in purification of ethanol separates volatile liquids on the basis of their relative volatilities. There are several type of distillation: simple distillation, steam distillation etc. Water purification combines a number of methods to produce potable or drinking water.
The key issue is that distillation operates based on phase changes, and this separation mechanism requires vast energy inputs. Dry distillation ( thermolysis and pyrolysis ) is the heating of solid materials to produce gases that condense either into fluid products or into solid products.
The method of extractive distillation uses a separation solvent, which is generally non-volatile, has a high boiling point and is miscible with the mixture, but doesn't form an azeotropic mixture. The solvent interacts differently with the components of the mixture thereby causing their relative volatilities to change.
A well-known example of a positive azeotrope is an ethanol–water mixture (obtained by fermentation of sugars) consisting of 95.63% ethanol and 4.37% water (by mass), which boils at 78.2 °C. [10] Ethanol boils at 78.4 °C, water boils at 100 °C, but the azeotrope boils at 78.2 °C, which is lower than either of its constituents. [11]
In this example, a mixture of 96% ethanol and 4% water boils at 78.2 °C (172.8 °F); the mixture is more volatile than pure ethanol. For this reason, ethanol cannot be completely purified by direct fractional distillation of ethanol–water mixtures. The apparatus is assembled as in the diagram.
Separation of components (e.g. water and ethanol) is based on a difference in transport rate of individual components through the membrane. This transport mechanism can be described using the solution-diffusion model, based on the rate/degree of dissolution of a component into the membrane and its velocity of transport (expressed in terms of ...
Extraction in chemistry is a separation process consisting of the separation of a substance from a matrix. The distribution of a solute between two phases is an equilibrium condition described by partition theory. This is based on exactly how the analyte moves from the initial solvent into the extracting solvent.