Question

describe filtration​

Answer 1

Answer:

Filtration is any of various mechanical, physical or biological operations that separates solids from fluids (liquids or gases) by adding a medium through which only the fluid can pass. The fluid that passes through is called the filtrate.

Filtration Methods

There are different types of filtration. Which method is used depends largely on whether the solid is a particulate (suspended) or dissolved in the fluid.

General Filtration: The most basic form of filtration is using gravity to filter a mixture. The mixture is poured from above onto a filter medium (e.g., filter paper) and gravity pulls the liquid down. The solid is left on the filter, while the liquid flows below it.

Vacuum Filtration: A Büchner flask and hose are used to create a vacuum to suck the fluid through the filter (usually with the aid of gravity). This greatly speeds the separation and can be used to dry the solid. A related technique uses a pump to form a pressure difference on both sides of the filter. Pump filters do not need to be vertical because gravity is not the source of the pressure difference on the sides of the filter.

Cold Filtration: Cold filtration is used to quickly cool a solution, prompting the formation of small crystals. This is a method used when the solid is initially dissolved. A common method is to place the container with the solution in an ice bath prior to filtration.

Hot Filtration: In hot filtration, the solution, filter, and funnel are heated to minimize crystal formation during filtration. Stemless funnels are useful because there is less surface area for crystal growth. This method is used when crystals would clog the funnel or prevent crystallization of the second component in a mixture.

Sometimes filter aids are used to improve flow through a filter. Examples of filter aids are silica, diatomaceous earth, perlite, and cellulose. Filter aids may be placed on the filter prior to filtration or mixed with the liquid. The aids can help prevent the filter from clogging and can increase the porosity of the "cake" or feed into the filter.