The term membrane most commonly refers to a thin, film-like structure that separates two fluids. It acts as a selective barrier, allowing some particles or chemicals to pass through, but not others. In some cases, especially in anatomy, membrane may refer to a thin film that is primarily a separating structure rather than a selective barrier.

The concept of a membrane has been known since the eighteenth century, but it remained as only a tool for physical / chemical theories development until the end of World War II, when drinking water supplies in Europe were compromised and membrane filters were used to test for water safety. However, due to the lack of reliability, slow operation, reduced selectivity and elevated costs, membranes were not widely exploited. The first use of membranes on a large scale was with microfiltration and ultra-filtration technologies. Since the 1980’s, these separation processes, along with electrodialysis, are employed in large plants and, today, a number of experienced companies serve the market.

A membrane is a layer of material which serves as a selective barrier between two phases and remains impermeable to specific particles, molecules, or substances when exposed to the action of a driving force. Some components are allowed passage by the membrane into a permeate stream, whereas others are retained by it and accumulate in the retentate stream.

Membranes can be of various thickness, with homogeneous or heterogeneous structure. Membrane can also be classified according to their pore diameter. According to IUPAC, there are three different types of pore size classifications: microporous (dp < 2 nm), mesoporous (2 nm < dp < 50 nm) and macroporous (dp > 50 nm). Membranes can be neutral or charged, and particles transport can be active or passive. The latter can be facilitated by pressure, concentration, chemical or electrical gradients of the membrane process. Membranes can be generally classified into synthetic membranes and biological membranes.

Read more about MembraneIndustrial Use

Other articles related to "membrane, membranes":

Bruch's Membrane - Pathology
... Bruch's membrane thickens with age, slowing the transport of metabolites ... (Basal Linear Deposits or BLinD and Basal Lamellar Deposits BLamD) on and within the membrane, primarily consisting of phospholipids ... This build up seems to fragment the membrane into a lamellar structure more like puff-pastry than a barrier ...
Endoplasmic-reticulum-associated Protein Degradation - ERAD Ubiquitination Machinery
... The ER membrane anchored RING finger containing ubiquitin ligases Hrd1 and Doa10 are the major mediators of substrate ubiquitination during ERAD ... The tail anchored membrane protein Ubc6 as well as Ubc1 and the Cue1 dependent membrane bound Ubc7 are the ubiquitin conjugating enzymes involved in ERAD ...
Bruch's Membrane - Layers
... Bruch's membrane consists of five layers (from inside to outside) the basement membrane of the retinal pigment epithelium the inner collagenous zone a central band of elastic ...
Membrane - Industrial Use
... Certain features of membranes are responsible for the interest in using them as substitutes to consolidated industrial separation processes, like distillation, adsorption or ... which facilitates the incorporation of more efficient membranes ...
... Epsins are the family of membrane proteins that are important in creating the needed membrane curvature ... Epsins contribute to various needed membrane deformations like endocytosis and block vesicle formation during mitosis ... (4,5)-bisphosphate, meaning that it binds a lipid of biological membranes ...