Filtration is one of a variety of mechanical, physical or biological operations that separate the solids from liquids (liquids or gases) by adding a medium that can only be passed by the liquid. The passing fluid is called filtrate . In physical filters, the excess solids in the fluid are retained and in particulate biological filters trapped and swallowed and the metabolites maintained and removed. However, its separation is incomplete; solids will be contaminated with some fluids and the filtrate will contain fine particles (depending on pore size, filter thickness and biological activity). Filtration occurs both in nature and in engineering systems; there are biological, geological, and industrial forms. For example, in animals (including humans), renal filtration removes waste from the blood, and in water treatment and waste treatment, unwanted constituents are removed by absorption into biological films implanted on or in filter media, such as slow sand filtration.
Video Filtration
Apps
- Filtration is used to separate particles and liquids in suspensions, in which liquids can be liquids, gases or supercritical fluids. Depending on the application, one or both components may be isolated.
- Filtration, as a physical operation is very important in chemistry for separation of different chemical composition ingredients. A solvent is selected which dissolves one component, while not dissolving the other components. By dissolving the mixture in the selected solvent, one component will enter the solution and pass through the filter, while the other will be maintained. This is one of the most important techniques used by chemists to purify compounds.
- Filtration is also important and widely used as one of the chemical engineering operations units. This may be simultaneously combined with other unit operations to process feed flows, such as in biofilters, which are combined filters and biological digestion devices.
- Filtration differs from sieving, where separation occurs in one hollow layer (sieve). In sieving, particles that are too large to pass through the filter holes are maintained (see particle size distribution). In filtration, the multilayer grid retains particles that can not follow the winding channels of the filter. Particles that are too large can form a layer of cake over the filter and may also block the filter grid, preventing the liquid phase from crossing the filter (blinding). Commercially, term filters are applied to the membrane where the separating lattice is so thin that the surface becomes the main zone of particle separation, although this product can be described as a filter.
- Filtration differs from adsorption, where it is not the physical size of the particles that cause separation but the effect of surface charge. Some adsorption devices that contain activated charcoal and ion exchange resins are commercially called filters, although filtration is not their primary function.
- Filtration differs from the removal of magnetic contaminants from liquids with magnets (usually lubricating oils, refrigerants and fuel oils), since there is no filter media. A commercial device called a 'magnetic filter' is sold, but its name reflects its use, not its mode of operation.
Maps Filtration
Method
There are many different filtering methods; all aim to achieve the separation of substances. Separation is achieved by some form of interaction between the substance or object to be removed and the filter. Substances passing through the filter must be liquid, ie liquid or gas. The filtration method varies depending on the location of the targeted material, ie whether it is dissolved in fluid phase or suspended as a solid.
There are several filtration techniques depending on the desired result ie, heat, cold and vacuum filtration. Some of the main purposes for obtaining the desired result are, to remove impurities from the mixture or, for the isolation of the solids from the mixture.
The Heat filter method is mainly used to separate the solids from the hot solution. This is done to prevent the formation of crystals in the filter funnel and other equipment in contact with the solution. As a result, the equipment and solutions used are heated to prevent rapid temperature drop which, in turn, leads to crystallization of solids in the funnel and inhibits the filtration process. One of the most important steps to prevent the formation of crystals in the funnel and to undergo effective heat filtration is the use of a non-rod filter funnel. Because of the absence of rods in the filter funnel, there is a decrease in contact surface between the solution and the filter funnel rod, thereby preventing the re-crystallization of solids in the funnel, affecting the filtration process.
The Cold Filtration method is the use of ice bath to cool the solution quickly to become crystallized rather than letting it out to cool it slowly at room temperature. This technique results in a very small crystal formation compared to obtaining large crystals by cooling the solution at room temperature.
The Vacuum Filtration technique is most preferred for small batch solutions for rapidly drying small crystals. This method requires a BÃÆ'¼chner funnel, a filter paper smaller than the funnel diameter, a BÃÆ'¼chner flask, and a rubber tube to connect to a vacuum source.
Media filter
Two main types of filter media are used in the laboratory: a surface filter, a solid screen that traps solid particles, with or without the help of filter paper (eg BÃÆ'¼chner funnel, Belt filter, Rotary vacuum- drum filter, cross- filter display); and depth filters , beds of granular material that retain solid particles as they pass (eg sand filters). The first type allows solid particles, ie residues, to be collected intact; the second type does not allow this. However, the second type is less prone to clogging due to the larger surface area where particles can be trapped. Also, when solid particles are very fine, it is often cheaper and easier to get rid of contaminated granules than to clean a solid filter.
Filter media can be cleaned by rinsing with solvents or detergents. Or, in engineering applications, such as swimming pool water treatment plants, they may be cleaned by washing again. A self-cleaning screen using point-of-suction backwash to clear the screen without disrupting system flow.
Reach flow through filter
The liquid flows through the filter because of the difference in pressure - the liquid flow from the high pressure side to the low pressure side of the filter, leaving some matter behind. The simplest method to achieve this is by gravity and can be seen in the coffee maker example. In the laboratory, pressure in the form of compressed air at the feed side (or vacuum on the filtrate side) can be applied to make the filtration process faster, although this may cause blockage or passage of fine particles. Alternatively, the liquid can flow through the filter by force provided by the pump, a method commonly used in industry when reduced filtration time is important. In this case, the filter does not need to be installed vertically.
Filter help
Specific filter tools can be used to aid filtering. It is a non-compacted diatomous earth, or kieselguhr, which consists mainly of silica. Also used are wood cellulose and other inert porous solids such as pearls which are cheaper and safer.
This filter tool can be used in two different ways. They can be used as precoat before the slurry is filtered. This will prevent the agar-agar substances from plugging the filter media and also provide a clearer filtrate. They can also be added to the slurry before filtering. This increases the porosity of the cake and reduces the cake's durability during screening. In rotary filters, filter assistance can be applied as precoat; furthermore, the thin slices of this layer are cut with the cake.
The use of filter aids is usually limited to cases where the cake is discarded or where the precipitate can be chemically separated from the filter.
Alternative
Filtration is a more efficient method for mixed separation than decantation, but it is much more time consuming. If a small amount of solution is involved, most of the solution can be immersed by the filter media.
The alternative to filtration is centrifugation - rather than filtering the mixture of solid and liquid particles, the mixture is centrifuged to force (usually) solid solids downward, where it often forms a sturdy cake. The above liquid can then be poured. This method is particularly useful for separating unscreened solids, such as gelatin or fine particles. This solid can clog or pass filter, respectively.
Example
Examples of filtering include
- Coffee filters to keep coffee separate from the yard.
- HEPA filters air conditioning to remove particles from the air.
- Filter the belt to extract precious metals in mining.
- Horizontal plate filters, also known as Sparkler filters.
- Furnaces use filtration to prevent furnace elements from fouling with particulates.
- Pneumatic transport systems often use filtration to stop or slow the flow of transported material, through the use of baghouse.
- In the laboratory, the BÃÆ'¼chner funnel is often used, with filter paper serving as a porous barrier.
- Air filters are commonly used to remove airborne particles in building ventilation systems, combustion engines, and industrial processes.
Experiments to prove the existence of microscopic organisms involve comparisons of water passing through glazeless porcelain and unfiltered water. When left in a sealed container, filtered water takes longer to leave, indicating that very small objects (such as bacteria) can be removed from the liquid by filtration.
In the kidney, renal filtration is blood filtering in the glomerulus, followed by selective reabsorption of many important substances for the body to maintain homeostasis.
See also
References
Source of the article : Wikipedia
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