Filtration is a physical separation process that separates solid matter and fluid from a mixture using a filter medium that has a complex structure through which only the fluid can pass. Solid particles that cannot pass through the filter medium are described as oversize and the fluid that passes through is called the filtrate. Oversize particles may form a filter cake on top of the filter and may also block the filter lattice, preventing the fluid phase from crossing the filter, known as blinding. The size of the largest particles that can successfully pass through a filter is called the effective pore size of that filter. The separation of solid and fluid is imperfect; solids will be contaminated with some fluid and filtrate will contain fine particles. Filtration occurs both in nature and in engineered systems; there are biological, geological, and industrial forms.
Hot filtration, solution contained in the Erlenmeyer flask is heated on a hot plate to prevent re-crystallization of solids in the flask itself
Hot filtration for the separation of solids from a hot solution
Cold filtration, the ice bath is used to cool down the temperature of the solution before undergoing the filtration process
Small stationary Bauer HP breathing air compressor installation showing water separator (centre), and two high-pressure product filter housings (gold anodised) to produce oxygen compatible breathing air for diving gas mixtures.
Filter paper is a semi-permeable paper barrier placed perpendicular to a liquid or air flow. It is used to separate fine solid particles from liquids or gases.
Filter paper: used for separating solid from liquid.
Air filter paper in an auto engine
Oil filter cut-away with paper visible inside
A scan of Whatman Filter Paper 4 Qualitative taken at 840 magnifications under a scanning electron microscope.