Ceramic membranes are a type of

artificial membrane An artificial membrane, or synthetic membrane, is a synthetically created membrane which is usually intended for separation purposes in laboratory or in industry. Synthetic membranes have been successfully used for small and large-scale industrial ...

s made from

inorganic In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...

materials (such as alumina, titania, zirconia oxides,

silicon carbide Silicon carbide (SiC), also known as carborundum (), is a hard chemical compound containing silicon and carbon. A semiconductor, it occurs in nature as the extremely rare mineral moissanite, but has been mass-produced as a powder and crystal sin ...

or some glassy materials). They are used in membrane operations for liquid filtration. By contrast with

polymeric membranes An artificial membrane, or synthetic membrane, is a synthetically created membrane which is usually intended for separation purposes in laboratory or in industry. Synthetic membranes have been successfully used for small and large-scale industrial ...

, they can be used in separations where aggressive media (acids, strong solvents) are present. They also have excellent thermal stability which makes them usable in high-temperature membrane operations. Like polymeric membranes, they are either dense or porous. Configurations include tubular cross flow and dead-end membranes as well as flat sheet membranes.

Dense membranes

Dense ceramic membranes are used for the purpose of gas separation. Examples are the separation of oxygen from air, or the separation of hydrogen gas from a mixture.

Porous membranes

Porous ceramic membranes are chiefly used for

gas separation Gas separation can refer to any of a number of techniques used to separate gases, either to give multiple products or to purify a single product. Swing adsorption techniques Pressure swing adsorption Pressure swing adsorption (PSA) pressurizes ...

and

micro- ''Micro'' (Greek letter μ ( U+03BC) or the legacy symbol µ (U+00B5)) is a unit prefix in the metric system denoting a factor of 10−6 (one millionth). Confirmed in 1960, the prefix comes from the Greek ('), meaning "small". The symbol for th ...

nanofiltration Nanofiltration is a membrane filtration process used most often to soften and disinfect water. Overview Nanofiltration is a Membrane technology, membrane filtration-based method that uses nanometer sized pores through which particles smaller t ...

. They can be made from both

crystalline A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macrosc ...

as well as

amorphous In condensed matter physics and materials science, an amorphous solid (or non-crystalline solid, glassy solid) is a solid that lacks the long-range order that is characteristic of a crystal. Etymology The term comes from the Greek ''a'' ("wi ...

solids. An example of an amorphous membrane is the silica membrane. An example of a highly porous membrane is the type made of

History & manufacturers of ceramic membranes

The first ceramic membranes were produced in France in the 1980s for the purpose of uranium enrichment in the nuclear industry. After many of the nuclear plants were set up in France other industrial application areas for the ceramic membranes were sought out. At the same time academic research on ceramic membranes was conducted. The leading group was directed by Professor Louis Cot at the National Graduate School of Chemistry in Montpellier. The group growth gave rise to the creation of a laboratory fully dedicated to the membrane materials and processes from 1994 and to the European Membrane Institute of Montpellier in 2000. French manufacturers of ceramic membranes include Orelis Environnement (Alsys group), Pall Exekia and Tami Industries. Other companies outside France include CoorsTek (http://www.coorstek.com), Atech (http://www.atech-innovations.com), Inopor, Jiangsu Jiuwu, Meidensha, MetaWater, Liqtech, and Mantec Technical Ceramics Ltd (http://www.mantectechnicalceramics.com/products-services/porous-ceramics/filtration/star-sep-membranes/elements) While most of the ceramic membrane manufacturers produce the membranes of carriers and membrane layers of alumina oxide, titanium oxide and zirconia oxide only a few manufacturers work with silicon carbide. Silicon carbide requires higher sintering temperatures (>2000 °C) compared to oxide based membranes (1200-1600 °C). The pioneers in developing and commercializing silicon carbide membranes are the Danish company Liqtech, CeraMem (Alsys group) and American company Kemco Systems.

References

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