Zeolites (Greek, zein, "to boil"; lithos, "a stone") are hydrated aluminosilicate minerals and have a micro-porous structure. Aluminosilicate Minerals are minerals composed of Aluminium, Silicon, and oxygen A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition a highly ordered atomic structure and specific
The term was originally coined in the 18th century by a Swedish mineralogist named Axel Fredrik Cronstedt who observed, upon rapidly heating a natural mineral, that the stones began to dance about as the water evaporated. The 18th century lasted from 1701 to 1800 in the Gregorian calendar, in accordance with the Anno Domini / Common Era numbering system "Sverige" redirects here For other uses see Sweden (disambiguation and Sverige (disambiguation. Mineralogy is an Earth Science focused around the Chemistry, Crystal structure, and physical (including optical) properties of Minerals Baron Axel Fredrik Cronstedt (1722 – 1765 was a Swedish Chemist who discovered Nickel in 1751 he was a mining expert with the Bureau of Mines Using the Greek words which mean "stone that boils," he called this material zeolite.
More than 150 zeolite types have been synthesized and 48 naturally occurring zeolites are known. Zeolites have an "open" structure that can accommodate a wide variety of cations, such as Na+, K+, Ca2+, Mg2+ and others. An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge These positive ions are rather loosely held and can readily be exchanged for others in a contact solution. Some of the more common mineral zeolites are: analcime, chabazite, heulandite, natrolite, phillipsite, and stilbite. Analcime or analcite (from the Greek analkimos - "weak" is a white grey or colourless tectosilicate Mineral. Chabazite is a tectosilicate Mineral of the Zeolite group with formula (CaNa2K2MgAl2Si4O12·6H2O Heulandite is the name of a series of tecto-silicate Minerals of the Zeolite group Natrolite is a tectosilicate Mineral species belonging to the Zeolite group Phillipsite is a mineral of the Zeolite group a hydrated Potassium, Calcium and Aluminium silicate approximating to ( Ca, Na Stilbite is a tectosilicate Mineral of the Zeolite group consisting of hydrated Calcium Aluminium Silicate, Na[[calcium An example mineral formula is: Na2Al2Si3O10-2H2O, the formula for natrolite.
Natural zeolites form where volcanic rocks and ash layers react with alkaline groundwater. Plate tectonics and hotspots Divergent plate boundaries At the Volcanic ash consists of small Tephra, which are bits of pulverized rock and glass created by volcanic eruptions less than in diameter In Chemistry, an alkali (from Arabic: Al-Qaly القلي القالي) is a basic, ionic salt of an Alkali metal Zeolites also crystallized in post-depositional environments over periods ranging from thousands to millions of years in shallow marine basins. Naturally occurring zeolites are rarely pure and are contaminated to varying degrees by other minerals, metals, quartz or other zeolites. For this reason, naturally occurring zeolites are excluded from many important commercial applications where uniformity and purity are essential.
Zeolites are the aluminosilicate members of the family of microporous solids known as "molecular sieves". The term molecular sieve refers to a particular property of these materials, i. A molecular sieve is a material containing tiny pores of a precise and uniform size that is used as an adsorbent for Gases and Liquids Molecules e. the ability to selectively sort molecules based primarily on a size exclusion process. This is due to a very regular pore structure of molecular dimensions. The maximum size of the molecular or ionic species that can enter the pores of a zeolite is controlled by the diameters of the tunnels. These are conventionally defined by the ring size of the aperture, where, for example, the term "8ring" refers to a closed loop that is built from 8 tetrahedrally coordinated silicon (or aluminium) atoms and 8 oxygen atoms. These rings are not always perfectly flat and symmetrical due to a variety of effects, including strain induced by the bonding between units that are needed to produce the overall structure, or coordination of some of the oxygen atoms of the rings to cations within the structure. Therefore, the pore openings for all rings of one size are not identical.
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Conventional open pit mining techniques in Arkansas are used to mine natural zeolites. Open-pit mining, also known as opencast mining and open-cut mining and strip mining, refers to a method of extracting rock or Minerals The overburden is removed to allow access to the ore. The ore may be blasted or stripped for processing by using tractors equipped with ripper blades and front-end loaders. In processing, the ore is crushed, dried, and milled. The milled ore may be air-classified as to particle size and shipped in bags or bulk. The crushed product may be screened to remove fine material when a granular product is required, and some pelletized products are produced from fine material. Producers also may modify the properties of the zeolite or blend their zeolite products with other materials before sale to enhance their performance.
Currently, the world’s annual production of natural zeolite is about 4 million tons. Of this quantity, 2. 6 million tons are shipped to Chinese markets to be used in the concrete industry. Concrete is a construction material composed of Cement (commonly Portland cement) as well as other cementitious materials such as Fly ash and Slag Eastern Europe, Western Europe, Australia, and Asia are world leaders in supplying the world’s demand for natural zeolite. By comparison, only 57,400 metric tons (source: U. S. Geological Survey, 2004) of zeolite (only 1% of the world’s current production) is produced in North America; only recently has North America realized the potential for current and future markets.
There are several types of synthetic zeolites that form by a process of slow crystallization of a silica-alumina gel in the presence of alkalis and organic templates. In Materials science, a crystal is a Solid in which the constituent Atoms Molecules or Ions are packed in a regularly ordered repeating The Chemical compound silicon dioxide, also known as silica or silox (from the Latin " Silex " is an Oxide One of the important processes used to carry out zeolite synthesis is sol-gel processing. The sol-gel process is a wet-chemical technique ( Chemical Solution Deposition) for the fabrication of materials (typically a Metal oxide) starting either from a chemical The product properties depend on reaction mixture composition, pH of the system, operating temperature, pre-reaction 'seeding' time, reaction time as well as the templates used. In sol-gel process, other elements (metals, metal oxides) can be easily incorporated. The silicalite sol formed by the hydrothermal method is very stable. Hydrothermal circulation in its most general sense is the circulation of hot water 'hydros' in the Greek meaning water and 'thermos' meaning heat Also the ease of scaling up this process makes it a favorite route for zeolite synthesis.
Synthetic zeolites hold some key advantages over their natural analogs. The synthetics can, of course, be manufactured in a uniform, phase-pure state. It is also possible to manufacture desirable zeolite structures which do not appear in nature. Zeolite A is a well-known example. Since the principal raw materials used to manufacture zeolites are silica and alumina, which are among the most abundant mineral components on earth, the potential to supply zeolites is virtually unlimited. Finally, zeolite manufacturing processes engineered by man require significantly less time than the 50 to 50,000 years prescribed by nature. Disadvantages include the inability to create crystals with dimensions of a comparable size to their natural counterparts.
Uses
Commercial and Domestic
Zeolites are widely used as ion-exchange beds in domestic and commercial water purification, softening, and other applications. Water purification is the process of removing contaminants and other harmful microorganisms from a raw water source In chemistry, zeolites are used to separate molecules (only molecules of certain sizes and shapes can pass through), as traps for molecules so they can be analyzed. In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by
Zeolites have the potential of providing precise and specific separation of gases including the removal of H2O, CO2 and SO2 from low-grade natural gas streams. Natural gas is a Gaseous Fossil fuel consisting primarily of Methane but including significant quantities of Ethane, Propane, Other separations include: noble gases, N2, O2, freon and formaldehyde. History Noble gas is translated from the German noun de ''Edelgas'' first used in 1898 by Hugo Erdmann to indicate their extremely low level of reactivity Freon is DuPont 's trade name for its odorless colorless nonflammable and noncorrosive Chlorofluorocarbon and Hydrochlorofluorocarbon Refrigerants Formaldehyde is a Chemical compound with the formula H2CO It is the simplest Aldehyde —an organic compound containing a terminal Carbonyl However at present, the true potential to improve the handling of such gases in this manner remains unknown.
Petrochemical industry
Synthetic zeolites are widely used as catalysts in the petrochemical industry, for instance in fluid catalytic cracking and hydro-cracking. Catalysis is the process in which the rate of a Chemical reaction is increased by means of a Chemical substance known as a catalyst In Petroleum geology and Chemistry, cracking is the process whereby complex organic Molecules such as Kerogens or heavy Hydrocarbons Zeolites confine molecules in small spaces, which causes changes in their structure and reactivity. The hydrogen form of zeolites (prepared by ion-exchange) are powerful solid-state acids, and can facilitate a host of acid-catalyzed reactions, such as isomerisation, alkylation, and cracking. Ion exchange is an exchange of Ions between two Electrolytes or between an electrolyte Solution and a complex. In Computer science, ACID ( Atomicity Consistency Isolation Durability) is a set of properties that guarantee that Database transactions are In Chemistry isomerisation is the process by which one Molecule is transformed into another molecule which has exactly the same atoms but the atoms are rearranged Alkylation is the transfer of an Alkyl group from one Molecule to another Catalytic cracking uses a furnace and reactor. First crude oil distillation fractions are heated in the furnace and passed to the reactor. In the reactor the crude meets with a catalyst such as zeolite. It goes through this step three times, each time getting cooler. Finally it reaches a step known as separator. The separator collects recycled hydrogen. Then it goes through a fractionator and becomes the final item.
Nuclear Industry
Zeolites have uses in advanced reprocessing methods, where their micro-porous ability to capture some ions while allowing others to pass freely allow many fission products to be efficiently removed from nuclear waste and permanently trapped. Equally important are the mineral properties of zeolites. Their alumino-silicate construction is extremely durable and resistant to radiation even in porous form. Additionally, once they are loaded with trapped fission products, the zeolite-waste combination can be hot pressed into an extremely durable ceramic form, closing the pores and trapping the waste in a solid stone block. This is a waste form factor that greatly reduces its hazard compared to conventional reprocessing systems. [1]
Agriculture
In agriculture, clinoptilolite (a naturally occurring zeolite) is used as a soil treatment. Clinoptilolite is a natural Zeolite comprising a microporous arrangement of silica and alumina tetrahedra It provides a source of slowly released potassium. Potassium (pəˈtæsiəm is a Chemical element. It has the symbol K (kalium from qalīy Atomic number 19 and Atomic mass 39 If previously loaded with ammonium, the zeolite can serve a similar function in the slow release of nitrogen. Ammonium is also an old name for the Siwa Oasis in western Egypt. Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 Zeolites can also act as water moderators, in which they will absorb up to 55% of their weight in water and slowly release it under plant demand. This property can prevent root rot and moderate drought cycles.
Animal Welfare
In Concentrated Animal Growing facilities, the addition of as little as 1% of a very low sodium clinoptiloite was shown to improve feed conversion, reduce airborne ammonia up to 80%, act as a mycotoxin binder and improve bone density. See US Patents 4,917,045 and 6,284,232. Can be used in general odor elimination for all animal odors.
Medical
Zeolite-based oxygen concentrator systems are widely used to produce medical grade oxygen. The zeolite is used as a molecular sieve to create purified oxygen from air using its ability to trap impurities, in a process involving the absorption of undesired gases and other atmospheric components, leaving highly purified oxygen and up to 5% argon. Zeolite was once the active component in QuikClot, a hemostatic agent used as an emergency coagulant in the veterinary industry before being found to be toxic.
Heating and refrigeration
Zeolites can be used as solar thermal collectors and for adsorption refrigeration. A solar thermal collector is a Solar collector specifically intended to collect Heat: that is to absorb Sunlight to provide heat The absorption refrigerator is a Refrigerator that utilizes a heat source (e In these applications, their high heat of adsorption and ability to hydrate and dehydrate while maintaining structural stability is exploited. This hygroscopic property coupled with an inherent exothermic reaction when transitioning from a dehydrated to a hydrated form (heat adsorption), make natural zeolites effective in the storage of solar and waste heat energy. Hygroscopy is the ability of a substance to attract Water Molecules from the surrounding environment through either absorption or Adsorption In Thermodynamics, the word exothermic "outside heating" describes a process or reaction that releases Energy usually in the form of Heat, but
Detergents
The largest single use for zeolite is the global laundry detergent market. A detergent (as a noun is a material intended to assist Cleaning. This amounted to 1. 44 million metric tons per year of anhydrous zeolite A in 1992.
Construction
Synthetic zeolite is also being used as an additive in the production process of warm mix asphalt concrete. Asphalt concrete, normally known simply as Asphalt, is a Composite material commonly used for construction of pavement, Highways and The development of this application started in Europe (Germany) in the 1990s. It helps by decreasing the temperature level during manufacture and laying of asphalt concrete, resulting in lower consumption of fossil fuels, thus releasing less carbon dioxide,aerosols and vapours. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single Other than that the usage of synthetic zeolite in hot mixed asphalt leads to easier compaction and to a certain degree allows cold weather paving and longer hauls.
When added to Portland Cement as a Pozzolan, it can reduce chloride permeability and improve workability. It reduces weight and helps moderate water content while allowing for slower drying which improves break strength. [1]
Gemstones
Thomsonites, one of the rarer zeolite minerals, have been collected as gemstones from a series of lava flows along Lake Superior in Minnesota and to a lesser degree in Michigan, U. Thomsonite is the name of a series of tecto-silicate Minerals of the Zeolite group A gemstone or gem, also called a precious or semi-precious stone, is a piece of attractive Mineral, which &mdash when cut and polished &mdash Lava is molten rock expelled by a Volcano during an eruption When first expelled from a volcanic vent it is a Liquid at Temperatures Lake Superior is the largest of the five Great Lakes of North America. Minnesota ( Native Americans demonstrated the name to early settlers Michigan ( is a Midwestern state of the United States of America. S. A. . Thomsonite nodules from these areas have eroded from basalt lava flows and are collected on beaches and by scuba divers in Lake Superior. Erosion is the carrying away or displacement of solids ( Sediment, Soil, rock and other particles usually by the agents of currents such as wind Basalt (bəˈsɔːlt ˈbeisɔːlt ˈbæsɔːlt is a common Extrusive Volcanic rock.
These thomsonite nodules have concentric rings in combinations of colors, black, white, orange, pink, red and many shades of green. Some nodules have copper as inclusions and rarely will be found with copper "eyes". Copper (ˈkɒpɚ is a Chemical element with the symbol Cu (cuprum and Atomic number 29 When polished by a lapidary the thomsonites sometimes display chatoyancy. A lapidary (the word means "concerned with stones" is an Artisan who practices the craft of working forming and finishing stone, Mineral, In Gemology, chatoyancy (or chatoyance) is an optical reflectance effect seen in certain Gemstones Coined from the French "oeil de chat" [2]
Aquarium keeping
Zeolites are marketed by pet stores for use as a filter additive in aquariums. An aquarium (plural aquariums or aquaria) is a Vivarium consisting of at least one transparent side in which Water -dwelling Plants In aquariums, zeolites can be used to absorb ammonia and other nitrogenous compounds. Ammonia is a compound with the formula N[[hydrogen H3]] It is normally encountered as a Gas with a characteristic pungent Odor However, due to the high affinity of some zeolites for calcium, they may be less effective in hard water and may deplete calcium. Zeolite filtration is used in some marine aquaria to keep nutrient concentrations low for the benefit of corals adapted to nutrient-depleted waters.
Where and how the zeolite was formed is an important consideration for aquariums. An aquarium (plural aquariums or aquaria) is a Vivarium consisting of at least one transparent side in which Water -dwelling Plants Northern hemisphere natural zeolites were formed when molten lava came in contact with sea water, thereby 'loading' the zeolite with Na (sodium) sacrifical ions. These sodium ions will speciate with other ions in solution, thus the takeup of nitrogen in ammonia, with the release of the sodium. In southern hemisphere zeolites, such as found in Australia, which were formed with fresh water, thus the calcium uptake on formation.
Zeolite is an effective ammonia filter, but must be used with some care, especially with delicate tropical corals which are sensitive to water chemistry and tempreature.
Space hardware testing
Zeolites can be used as a molecular sieve in cryosorption pumps for rough pumping of vacuum chambers which can be used to simulate space-like conditions in order to test hardware bound for space. A cryopump is a Vacuum pump that traps Gases and Vapours by condensing them on a cold surface vacuum chamber is a rigid enclosure from which air and other gases are removed by a Vacuum pump.
Cat litter
Non-clumping cat litter is often made of zeolite or diatomite. Cat litter (often called kitty litter) is one of any of a number of materials used in Litter boxes to absorb moisture from Cat Feces and Diatomaceous earth (ˌdaɪətəˈmeɪʃəs ˈɝθ also known as DE, TSS, diatomite, diahydro, kieselguhr, kieselgur and
Zeolite mineral species
The Zeolite family includes
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Notes
- ^ Dypayan Jana, CLINOPTILOLITE – A PROMISING POZZOLAN IN CONCRETE, http://www.cmc-concrete.com/CMC%20Seminars/2007%20ICMA%20Zeolite.pdf
- ^ http://www.cst.cmich.edu/users/dietr1rv/thomsonite.htm R. Analcime or analcite (from the Greek analkimos - "weak" is a white grey or colourless tectosilicate Mineral. Brewsterite is the name of a series of tecto-silicate Minerals of the Zeolite group Chabazite is a tectosilicate Mineral of the Zeolite group with formula (CaNa2K2MgAl2Si4O12·6H2O Clinoptilolite is a natural Zeolite comprising a microporous arrangement of silica and alumina tetrahedra Edingtonite is a white gray brown colorless pink or yellow Mineral. The ferrierite group of Zeolite Minerals (the FER structure consists of three very similar species ferrierite- Mg, ferrierite- Na, and ferrierite- Gismondine is a Mineral with the chemical formula CaAl2Si2O8·4(H2O Gmelinite is one of the rarer of the Zeolite minerals being a hydrated Silicate of Calcium, Aluminium and either Sodium or Potassium Harmotome is a mineral one of the rarer Zeolites; a hydrated Barium Silicate with formula ( Ba 0 Heulandite is the name of a series of tecto-silicate Minerals of the Zeolite group Laumontite is a Mineral, one of the Zeolite group Its molecular formula is (2 · 4 H2O, a hydrated calcium-aluminium Levyne or levynite is a Zeolite mineral ie a hydrated silicate mineral. Mesolite is a tectosilicate mineral with formula Na 2 Ca 2( Al 2 Si 3 O 103·8 Mordenite is a rare Zeolite Mineral with the chemical formula ( Ca, Na 2 K 2 Al 2 Si Natrolite is a tectosilicate Mineral species belonging to the Zeolite group Paulingite or paulingite-K is a rare Zeolite mineral that is found in vesicles in the Alluvial basaltic rocks from the Columbia River near Phillipsite is a mineral of the Zeolite group a hydrated Potassium, Calcium and Aluminium silicate approximating to ( Ca, Na Pollucite is a Zeolite mineral with the formula ( Cs, Na)2 Al 2 Si 4 O 12·2 H2O Scolecite is a tectosilicate Mineral belonging to the Zeolite group a hydrated Calcium Silicate, Ca Al 2 Stilbite is a tectosilicate Mineral of the Zeolite group consisting of hydrated Calcium Aluminium Silicate, Na[[calcium Thomsonite is the name of a series of tecto-silicate Minerals of the Zeolite group V. Dietrich, 2006, Thomsonite
References
- Zeolites in Sedimentary Rocks. Ch. in United States Mineral Resources, Professional Paper 820, 1973.
- Natural and Synthetic Zeolites. U. S. Bureau of Mines Information Circular 9140, 1987.
- La roca magica: Uses of natural zeolites in agriculture and industry
Frederick A. Mumpton. National Academy of Sciences Vol. 96, Issue 7, 3463-3470, March 30, 1999 Abstract
- “Zeolite-water close cycle solar refrigeration ; numerical optimisation and field-testing”, Jean-Baptiste Monnier; Dupont, M. Proc. Annu. Meet. - Am. Sect. Int. Sol. Energy Soc. ; Vol/Issue: 6 pp 181-185; American Solar Energy Society meeting; 1 June 1983; Minneapolis, MN, USA
See also
External links
- Database of Zeolite Structures
- The Synthesis Commission of the International Zeolite Association
- British Zeolite Association
- U.S. Geological Survey, References on Zeolites
Dictionary
zeolite
-noun
- (mineralogy) Any of several minerals, aluminosilicates of sodium, potassium, calcium or magnesium, that have a porous structure; they are used in water softeners and in ion exchange chromatography.
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