Miscellaneous Process By: Dr. Tahseen Ismail By: Dr. Tahseen Ismail

Spray Drying Spray drying is one of the methods of desiccation by which solutions or slurries are dried. Spray drying is one of the methods of desiccation by which solutions or slurries are dried. The apparatus used for this purpose is known as spray drier. These driers consist of a hot air chamber into which liquid to be dried is fed from the top and hot air is supplied from the base. The apparatus used for this purpose is known as spray drier. These driers consist of a hot air chamber into which liquid to be dried is fed from the top and hot air is supplied from the base. The spraying of the liquid is done either by pressure jets. By the high current of hot air the liquid is sprayed The spraying of the liquid is done either by pressure jets. By the high current of hot air the liquid is sprayed in the form of a mist, the droplets of which are readily evaporated and the dried particles fall to the bottom of the chamber from where they are collected. in the form of a mist, the droplets of which are readily evaporated and the dried particles fall to the bottom of the chamber from where they are collected. The exhausted air leaves the chamber through the air outlet. The exhausted air leaves the chamber through the air outlet.

Different types of spray driers are available with various modifications. In some forms of spray driers the liquid to be dried and hot air enters from the top of the chamber and in others from the bottom. Still in other types liquid is fed from the top and hot air from the bottom Different types of spray driers are available with various modifications. In some forms of spray driers the liquid to be dried and hot air enters from the top of the chamber and in others from the bottom. Still in other types liquid is fed from the top and hot air from the bottom

Applications 1. These driers are very useful because the drying is very rapid as large surface of liquid is exposed to hot air and temperature required for drying is also low. Therefore heat sensitive products can be dried conveniently. 1. These driers are very useful because the drying is very rapid as large surface of liquid is exposed to hot air and temperature required for drying is also low. Therefore heat sensitive products can be dried conveniently. 2. Spray drying is used for drying blood plasma, milk and enzyme preparations such as pancreatin and pepsin. 2. Spray drying is used for drying blood plasma, milk and enzyme preparations such as pancreatin and pepsin. 3. Spray driers can be designed for drying under sterile conditions. 3. Spray driers can be designed for drying under sterile conditions. 4. Solid and liquid particles can be encapsulated by employing spray drying. 4. Solid and liquid particles can be encapsulated by employing spray drying.

Levigation The process of levigations is also known as wet grinding. In this method the particle size of a substance is reduced to fine state of subdivision by triturating the substance with a few drops of liquids to which it is insoluble, in a glass mortar with the pestle or on a slab with spatula.The most commonly used levigating agents includes are oils, water, alcohols and glycerin. The process of levigations is also known as wet grinding. In this method the particle size of a substance is reduced to fine state of subdivision by triturating the substance with a few drops of liquids to which it is insoluble, in a glass mortar with the pestle or on a slab with spatula.The most commonly used levigating agents includes are oils, water, alcohols and glycerin.

Uses of levigation Can be use to incorporate solid substances into: Can be use to incorporate solid substances into: dermatological preparations dermatological preparations ophthalmic ointments. ophthalmic ointments. suspensions suspensions

Pulverization by Intervention This is a process by which the solid substances are reduced to a fine powder by mean of triturating the solid using suitable solvent which can bee easily removed by the end of process. This is a process by which the solid substances are reduced to a fine powder by mean of triturating the solid using suitable solvent which can bee easily removed by the end of process. Camphor is triturated with few drop of alcohols, ether or chloroform it can be powdered easily. The solvent added evaporate quickly leaving behind fine sub- divided particles of camphor. Camphor is triturated with few drop of alcohols, ether or chloroform it can be powdered easily. The solvent added evaporate quickly leaving behind fine sub- divided particles of camphor. Similarly iodine crystals may be powdered with the help of small quantiy of ether. Similarly iodine crystals may be powdered with the help of small quantiy of ether.

Elutriation: Definition: “Elutriation is the process in which the particles of the fluid move in a direction opposite to that of the sedimentation. (Downward movement)” Definition: “Elutriation is the process in which the particles of the fluid move in a direction opposite to that of the sedimentation. (Downward movement)” Explanation: In gravitational sedimentation the particles will move vertically downward while the fluid travels vertically upward. Explanation: In gravitational sedimentation the particles will move vertically downward while the fluid travels vertically upward. If the velocity of the fluid is less then the setting velocity of the particles, then the particles will move downward against the stream of fluid. If the setting velocity of particles is less then the velocity fluid, the particles will move upward. If the velocity of the fluid is less then the setting velocity of the particles, then the particles will move downward against the stream of fluid. If the setting velocity of particles is less then the velocity fluid, the particles will move upward.

In other words small size particles will move upward while the large size particles will move downward. In other words small size particles will move upward while the large size particles will move downward. So Elutriation is the process of separation of fine particles from course particles. The particles size can also be measured by this process. So Elutriation is the process of separation of fine particles from course particles. The particles size can also be measured by this process.

Apparatus used for Elutriation The apparatus used for Elutriation process is called as Elutriator. The apparatus used for Elutriation process is called as Elutriator. They are of two types: They are of two types: Gravitational Elutriation Gravitational Elutriation Centrifugal Elutriation Centrifugal Elutriation

Gravitational Elutriation 1- Gravitational Elutriation: 1- Gravitational Elutriation: In gravitational Elutriation the fluid particles move downward due to sedimentation (force of gravity) while the lighter particles remain upward. In gravitational Elutriation the fluid particles move downward due to sedimentation (force of gravity) while the lighter particles remain upward.

Centrifugal Elutriation: Centrifugal Elutriation causes the fluid stream to rotate under high centrifugal force to suspend the particles. These particles which are too large to rotate with direction of flow of fluid, separates out on the wall of the elutriator. However the fine particles move easily with the stream of fluid. Centrifugal Elutriation causes the fluid stream to rotate under high centrifugal force to suspend the particles. These particles which are too large to rotate with direction of flow of fluid, separates out on the wall of the elutriator. However the fine particles move easily with the stream of fluid.

Uses of Elutriation  Heavy and light Kaolin can be separated by this process, because the particles of heavy Kaolin move downward and those of the light Kaolin move upward.

DECANTATION Decantation is a process for the separation of mixtures. Decantation is a process for the separation of mixtures. Method: Method: Method consists of allowing the slurry to stand in a suitable vessel until the solids either settle down at the bottom. Now carefully pouring a solution from a container in order to leave the precipitate (sediment) in the bottom of the original container. Usually a small amount of solution must be left in the container, and care must be taken to prevent a small amount of precipitate from flowing with the solution out of the container. It is generally used to separate a liquid from an insoluble solid (e.g. in red wine, where the wine is decanted from the potassium bi tartrate crystals). Method consists of allowing the slurry to stand in a suitable vessel until the solids either settle down at the bottom. Now carefully pouring a solution from a container in order to leave the precipitate (sediment) in the bottom of the original container. Usually a small amount of solution must be left in the container, and care must be taken to prevent a small amount of precipitate from flowing with the solution out of the container. It is generally used to separate a liquid from an insoluble solid (e.g. in red wine, where the wine is decanted from the potassium bi tartrate crystals).

Separation of liquid from any other immiscible liquid can also be done by decantation.For example, Separation of liquid from any other immiscible liquid can also be done by decantation.For example, the oil and water extracted from olives may be decanted to obtain the olive oil. the oil and water extracted from olives may be decanted to obtain the olive oil. A mixture of kerosene and water can also be separated through decantation A mixture of kerosene and water can also be separated through decantation

CENTRIFUGATION Centrifugation is a process that involves the use of the centrifugal force for the separation of mixtures, used in industry and in laboratory settings. Centrifugation is a process that involves the use of the centrifugal force for the separation of mixtures, used in industry and in laboratory settings. More-dense components of the mixture migrate away from the axis of the centrifuge, while less-dense components of the mixture migrate towards the axis. More-dense components of the mixture migrate away from the axis of the centrifuge, while less-dense components of the mixture migrate towards the axis. The effective gravitational force on a test tube may be increased so as to more rapidly and completely cause the precipitate ("pellet") to gather on the bottom of the tube. The remaining solution is properly called the "supernate" or "supernatant liquid". The effective gravitational force on a test tube may be increased so as to more rapidly and completely cause the precipitate ("pellet") to gather on the bottom of the tube. The remaining solution is properly called the "supernate" or "supernatant liquid". The supernatant liquid is then either quickly decanted from the tube without disturbing the precipitate, or withdrawn with a Pasteur pipette. The supernatant liquid is then either quickly decanted from the tube without disturbing the precipitate, or withdrawn with a Pasteur pipette.

The rate of centrifugation is specified by the acceleration applied to the sample, typically measured in revolutions per minute (RPM). The rate of centrifugation is specified by the acceleration applied to the sample, typically measured in revolutions per minute (RPM). The particles' settling velocity in centrifugation is a function of their The particles' settling velocity in centrifugation is a function of their size and shape, size and shape, centrifugal acceleration, centrifugal acceleration, the volume fraction of solids present, the volume fraction of solids present, the density difference between the particle and the liquid, the density difference between the particle and the liquid, viscosity. viscosity.

VAPORIZATION Vaporization of an element or compound is a phase transition from the liquid or solid phase to gas phase. Vaporization of an element or compound is a phase transition from the liquid or solid phase to gas phase. There are three types of vaporization: There are three types of vaporization: evaporation, evaporation, boiling and boiling and sublimation. sublimation. Evaporation is a phase transition from the liquid phase to gas phase that occurs at temperatures below the boiling temperature at a given pressure. Note: evaporation usually occurs on the surface. Evaporation is a phase transition from the liquid phase to gas phase that occurs at temperatures below the boiling temperature at a given pressure. Note: evaporation usually occurs on the surface. Boiling is a phase transition from the liquid phase to gas phase that occurs at or above the temperature the boiling temperature. Boiling is a phase transition from the liquid phase to gas phase that occurs at or above the temperature the boiling temperature. Note: boiling occurs below the surface. Note: boiling occurs below the surface.