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Membrane separation processes

32 articles

General

Air gap membrane distillation

Air gap membrane distillation (AGMD) is a thermally driven desalination process in which water vapor crosses a hydrophobic membrane and an air gap, condensing as purified distillate.

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Bipolar membrane electrodialysis

Bipolar membrane electrodialysis (BMED), also written EDBM, is an electro-membrane process in which bipolar membranes split water, converting salts into their corresponding acids and bases without added chemical reagents.

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Bipolar membrane electrodialysis pH-swing CO2 capture

Bipolar membrane electrodialysis pH-swing CO2 capture is an electrochemical method in which bipolar membranes split water to swing a solvent's pH, releasing pure CO2 from flue gas, air, or ocean water.

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Ceramic membrane

A ceramic membrane is a separation membrane made of sintered metal oxides such as alumina, valued for chemical and thermal stability in water treatment and food processing.

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Concentration polarization

Concentration polarization is the buildup of rejected solute in a boundary layer at a membrane surface, lowering water flux and increasing solute leakage in membrane separations.

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Direct contact membrane distillation

Direct contact membrane distillation (DCMD) is a thermally driven membrane separation process used mainly for desalination, in which warm feed and cold permeate touch the same hydrophobic membrane.

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Forward osmosis

Forward osmosis is a membrane separation process in which water moves across a semipermeable membrane into a draw solution, driven by osmotic pressure rather than hydraulic pressure as in reverse osmosis.

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Gel layer

A gel layer is a concentrated layer of rejected macromolecular solute or colloidal particles that forms on a membrane surface during ultrafiltration, adding resistance and causing the limiting flux.

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Graphene oxide membrane

A graphene oxide membrane is a separation membrane built from stacked graphene oxide sheets, whose nanochannels selectively transport water, ions, and gases for desalination and gas separation.

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Hollow-fiber membrane

A hollow-fiber membrane is a fine self-supporting tube with a hollow lumen that acts as a selective filter; thousands bundled in a module serve desalination, water treatment, gas separation, and dialysis.

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Ion concentration polarization

Ion concentration polarization (ICP) is an electrokinetic phenomenon in which current through an ion-selective membrane creates ion depletion and enrichment zones, used for microfluidic desalination and water purification.

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Ion transport membrane

An ion transport membrane, also called an oxygen transport membrane, is a dense ceramic membrane separating near-pure oxygen from air at about 800 to 900 °C without cryogenic cooling.

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Ion-exchange membrane

An ion-exchange membrane is a dense, charged polymeric membrane that selectively passes oppositely charged ions by Donnan exclusion, used in electrodialysis, fuel cells, redox flow batteries, and water electrolysis.

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Membrane contactor

A membrane contactor is a separation device that transfers gas or liquid between two fluids across a microporous membrane, used for carbon dioxide capture and water degassing.

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Membrane fouling

Membrane fouling is the deposition of particles, colloids, macromolecules, and microorganisms on a membrane during filtration, cutting flux and raising pressure in processes like reverse osmosis.

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Microfiltration

Microfiltration is a pressure-driven membrane separation process that removes suspended particles, bacteria, and protozoan parasites from liquids or gases through porous membranes with pores of 0.1 to 10 µm.

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Mixed-matrix membrane

A mixed-matrix membrane (MMM) is a composite separation membrane combining a polymer matrix with inorganic fillers such as zeolites and MOFs, studied for gas separation, water treatment, and pervaporation.

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MOF-based mixed-matrix membranes

MOF-based mixed-matrix membranes, or MOF-based MMMs, combine metal-organic framework particles with a polymer matrix to raise both gas permeability and selectivity, chiefly for carbon dioxide, methane, and hydrogen separation.

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Nanofiltration

Nanofiltration (NF) is a pressure-driven membrane separation process that removes divalent ions and small organic molecules from water, used for water softening, dye desalting, and food and pharmaceutical processing.

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Oil–water separation membrane

An oil–water separation membrane is a porous, pressure-driven barrier that passes one phase of an oil–water mixture while rejecting the other, cleaning oily industrial wastewater or recovering oil.

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Pervaporation

Pervaporation is a membrane separation method in which a liquid mixture partially vaporizes through a selective membrane, used industrially to dehydrate solvents and break azeotropes.

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Photothermal membrane distillation

Photothermal membrane distillation, also called solar-driven membrane distillation, is a desalination method in which photothermal materials in the membrane convert light into heat, driving water vapor through while retaining salts.

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Planova

Planova is a brand of virus removal filters made by Asahi Kasei Medical, launched in 1989 as the world's first filter for virus removal in biotherapeutics manufacturing.

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Pressure retarded osmosis

Pressure retarded osmosis (PRO), also called osmotic power or blue energy, is a membrane process that generates electricity from the salinity difference between fresh water and pressurized salt water.

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Reverse electrodialysis

Reverse electrodialysis (RED) is a membrane-based technology that generates renewable electricity, sometimes called blue energy, from the controlled mixing of seawater and river water using ion exchange membranes.

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Supported liquid membrane

A supported liquid membrane (SLM), also called an artificial or immobilized liquid membrane, is a porous polymer support whose solvent-filled pores selectively transport solutes, mainly metal ions, between solutions.

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Thin-film composite membrane

A thin-film composite (TFC) membrane is a pressure-driven separation membrane with an ultrathin polyamide selective layer on a porous polymer support, developed by John Cadotte in the 1970s.

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Transmembrane pressure

Transmembrane pressure (TMP) is the difference in hydrostatic pressure between the two sides of a membrane, the driving force in microfiltration, ultrafiltration, nanofiltration, and reverse osmosis.

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Vacuum membrane distillation

Vacuum membrane distillation (VMD) is a thermally driven membrane separation process in which water vapor passes through a hydrophobic membrane under vacuum and condenses as desalinated water.

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Vapor permeation

Vapor permeation is a membrane separation process in which a vapor feed, typically a solvent and water mixture, contacts a dense membrane that selectively passes water.