Distillation part 1

Category: Entertainment

Presentation Description



Presentation Transcript

PowerPoint Presentation:



Distillation Distillation is defined as the separation of the components of a liquid mixture by a process involving vaporization and subsequent condensation at another place. The distillation process involves two steps: converting a liquid into vapour phase and Transferring the vapour to another place and recovering the liquid by condensation . The feed liquid is known as distilland . The condensed liquid is known as distillate or condensate. Distillation is said to be partial separation method. The extent of separation is governed by the properties of the components involved and the physical arrangements used for distillation.

PowerPoint Presentation:

Applications: Separation of volatile oils- cloves, aniseed,eucalyptus . Purification of organic solvents-absolute alcohol (100%). Manufacture of official preparations -sprit of nitrous ether, sprit of ammonia, D.water and water for inj. Refining of petroleum products- petroleum ether 60,80. Recovery of solvents- synthesis. Quality control methods- Alcohol content in elixir. Separation of drugs obtained from plant and animal sources- Vit . A from fish liver oil. Purification of drugs obtained from chemical process.


Theory Distillation is a process of separating and purifying the components in a liquid mixture. The primary data required to solve any distillation problem are vapour -liquid equilibrium relationship. Distillation method depends on the relative volatilities of the components present in the mixture.

PowerPoint Presentation:

Volatility The volatility of any substance in a solution may be defined as the equilibrium partial pressure of the substance in the vapour phase divided by the mole fraction of the substance in the solution . For example, a substance A in a liquid mixture has partial pressure P A and its concentration in the mixture is X A on mole fraction scale. Then volatility of A may be mathematically expressed as: partial vapour pressure of A Volatility of component A, v A = mole fraction X A of A in solution = P A X A The volatility of a material in the pure state is equal to the vapour pressure of the material. V A Relative Volatility = V B Relative volatility should never have a numerical value less than 1.0.

PowerPoint Presentation:

Aspects in the theory of Distillation: When two liquids are mixed together, they may be miscible with each other in all proportions. Such miscible liquids are known as binary mixtures of liquids. Examples of binary mixtures are ethyl alcohol and water, water and acetone, benzene and carbon tetrachloride . Ideal Solutions Ideal solution is defined as the one in which there is no change in the propertie s of the components other than dilution , when they are mixed to form a solution. Heat is neither absorbed nor evolved during mixing. The final volume of the solution represents the additive property of the individual constituents. Example is methanol and water, water and acetone, benzene and carbontetrachloride etc.

PowerPoint Presentation:

Raoult's Law Raoult's law expresses a quantitative relationship between the concentration and vapour pressure . It states that the partial vapour pressure of each volatile constituent is equal to the vapour pressure of the pure constituent multiplied by its mole fraction in the solution at a given temperature. Raoult's law may be mathematically expressed as: Partial vapour pressure = vapor pressure x mole fraction of the liquid of pure liquid of the liquid P A = p o A .X A P B = p o B .X B A mixture of ethylene chloride and benzene obeys Raoult's law. When two liquids are mixed, the vapour pressure of each one is reduced by the presence of other to the extent of dilution of each phase . Ideal solution is defined as the one that obeys Raoult's law. Raoult's law is obeyed by only a few solutions of liquid in liquids. These solutions are also known as 'perfect' solutions .

PowerPoint Presentation:

Total vapour pressure = partial pressure of A + partial pressure of B p = P A + P B p = p o A . X A + p O B .X B The properties are additive, ie ., the total vapour pressure of the mixture is the weighted average of the partial vapour pressures of pure individual constituents . The following conclusions can be drawn. The partial pressure of the component varies linearly from zero to full vapour pressure as the mole fraction varies from zero to one. The total pressure exerted by the system at a particular composition is equal to the sum of the partial pressures of its components.

PowerPoint Presentation:

Real solutions: Most systems show varying degree of deviation from Raoult’s Law , Depending on the nature of the liquids and the temperature . These solutions are known as Real solutions. Deviations are observed because solute-solute, solvent solute and solvent-solvent interactions are unequal . Ex: carbon tetrachloride and cyclohexane chloroform and acetone .

PowerPoint Presentation:

Positive Deviation: In some liquids systems, the total vapor pressure is greater than the sum of the partial pressures of the individual components Ex: benzene and ethanol. Differ in their polarity, length of hydrocarbon chain and degree of association. Negative Deviation: In some liquid systems, the total vapor pressure is lower than that of the sum of the partial pressures of the individual components. Ex: Chloroform and acetone Due to hydrogen bonding, salt formation and hydration

Distillation apparatus ::

Distillation apparatus :

General Equipment for Distillation::

General Equipment for Distillation: STILL : It is a vaporizing chamber and used to place the material to be distilled. The still is heated by a suitable means for vaporization of the volatile constituents. On laboratory scale round bottom flasks made of glass are used so that the progress of the distillation can be noticed. A condenser is attached to the still using appropriate joints . A trap is inserted between distillation flask and condenser.

PowerPoint Presentation:

CONDENSER : Used to condense the vapor It is kept cold by circulating water through water jacket. Types: Single-surface condensers Double-surface condensers Multi-tubular condensers The condenser is connected to a receiver through a suitable adapter.

PowerPoint Presentation:

RECEIVER : It is used to collect the distillate. It may be a simple flask. Florentine receivers are used for the separation of oil and water. Types: Type-I :- for separation of oil heavier than water. Type-II :- for separation of oil lighter than water.


TYPES OF DISTILLATION COLUMNS Batch Columns In batch operation, the feed to the column is introduced batch-wise. That is, the column is charged with a 'batch' and then the distillation process is carried out. When the desired task is achieved, a next batch of feed is introduced. Continuous Columns In contrast, continuous columns process a continuous feed stream . No interruptions occur unless there is a problem with the column or surrounding process units. They are capable of handling high throughputs and are the most common of the two types. We shall concentrate only on this class of columns.

authorStream Live Help