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Zeolite

Zeolites are microporous, aluminosilicate minerals commonly used as commercial adsorbents and catalysts. The term zeolite was originally coined in 1756 by Swedish mineralogist Axel Fredrik Cronstedt, who observed that rapidly heating a material, believed to have been stilbite, produced large amounts of steam from water that had been adsorbed by the material. Based on this, he called the material zeolite, from the Greekζέω (zéō), meaning "to boil" andλίθος (líthos), meaning "stone". The classic reference for the field has been Breck's book Zeolite Molecular Sieves: Structure, Chemistry, And Use.

Zeolites occur naturally but are also produced industrially on a large scale. As of December 2018[update], 253 unique zeolite frameworks have been identified, and over 40 naturally occurring zeolite frameworks are known. Every new zeolite structure that is obtained is examined by the International Zeolite Association Structure Commission and receives a three letter designation.

Contents

A form of thomsonite (one of the rarest zeolites) from India
Microscopic structure of a zeolite (mordenite) framework, assembled from SiO 4 {\displaystyle {\ce {SiO_4}}} tetrahedra. Sodium is present as an extra-framework cation (in green).

Zeolites have a porous structure that can accommodate a wide variety of cations, such as Na+, K+, Ca2+, Mg2+ and others. 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, clinoptilolite, heulandite, natrolite, phillipsite, and stilbite. An example of the mineral formula of a zeolite is:Na
2
Al
2
Si
3
O
10
·2H2O, the formula for natrolite. Cation exchanged zeolites possess different acidity and catalyse different reactions.[non-primary source needed]

Natural zeolites form where volcanic rocks and ash layers react with alkaline groundwater. Zeolites also crystallize 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.[citation needed]

Zeolites are the aluminosilicate members of the family of microporous solids known as "molecular sieves", and mainly consist of silicon, aluminum, oxygen, and have the general formula MxAlxSi1-xO2·yH2O where M is either a metal ion or H+. The value of x is between 0 and 1 and y is the number of water molecules in the formula unit. Although there are a wide range of possible structures a commonality is that they are formed by the linking of the corner oxygen atoms of AlO4 and SiO4 tetrahedra to form covalent network structures.

The term molecular sieve refers to a particular property of these materials, i.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 dimensions of the channels. These are conventionally defined by the ring size of the aperture, where, for example, the term "eight-ring" refers to a closed-loop that is built from eight tetrahedrally coordinated silicon (or aluminum) atoms and eight oxygen atoms. These rings are not always perfectly symmetrical due to a variety of causes, 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 pores in many zeolites are not cylindrical.

Zeolites transform to other minerals under weathering, hydrothermal alteration or metamorphic conditions. Some examples:

Industrially important zeolites are produced synthetically. Typical procedures entail heating aqueous solutions of alumina and silica with sodium hydroxide. Equivalent reagents include sodium aluminate and sodium silicate. Further variations include the use of structure directing agents (SDA) such as quaternary ammonium cations.

Synthetic zeolites hold some key advantages over their natural analogs. The synthetic materials are manufactured in a uniform, phase-pure state. It is also possible to produce zeolite structures that 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.

Natural occurrence

Natrolite from Poland

Conventional open-pit mining techniques are used to mine natural zeolites. 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.

As of 2016[update], the world's annual production of natural zeolite approximates 3 million tonnes. Major producers in 2010 included China (2 million tonnes), South Korea (210,000 t), Japan (150,000 t), Jordan (140,000 t), Turkey (100,000 t) Slovakia (85,000 t) and the United States (59,000 t). The ready availability of zeolite-rich rock at low cost and the shortage of competing minerals and rocks are probably the most important factors for its large-scale use. According to the United States Geological Survey, it is likely that a significant percentage of the material sold as zeolites in some countries is ground or sawn volcanic tuff that contains only a small amount of zeolites. Some examples of such usage include dimension stone (as an altered volcanic tuff), lightweight aggregate, pozzolanic cement, and soil conditioners.

Artificial synthesis

Synthetic zeolite

There are over 200 synthetic zeolites that have been synthesized by a process of slow crystallization of a silica-alumina gel in the presence of alkalis and organic templates. Many more such structures could theoretically be made. In addition to variations in structures, zeolites can also be made with a variety of other atoms in them to make them chemically interesting and active. Some examples of the so-called heteroatoms that have been incorporated include germanium, iron, gallium, boron, zinc, tin, and titanium. One of the important processes used to carry out zeolite synthesis is sol-gel processing. 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 the sol-gel process, other elements (metals, metal oxides) can be easily incorporated. The silicalite sol formed by the hydrothermal method is very stable. The ease of scaling up this process makes it a favored route for zeolite synthesis.

The zeolite conundrum

Computer calculations have predicted that millions of hypothetical zeolite structures are possible. However, only 232 of these structures have been discovered and synthesized so far, so many zeolite scientists question why only this small fraction of possibilities are being observed. This problem is often referred to as "the bottleneck problem".[citation needed] Currently, several theories are attempting to explain the reasoning behind this question.

  1. Zeolite synthesis research has primarily been concentrating on hydrothermal methods; however, new zeolites may be synthesized using alternative methods. Synthesis methods that have started to gain use include microwave-assisted, post-synthetic modification, steam.
  2. Geometric computer simulations have shown that the discovered zeolite frameworks possess a behavior known as "the flexibility window". This shows that there is a range in which the zeolite structure is "flexible" and can be compressed but retain the framework structure. It is suggested that if a framework does not possess this property then it cannot be feasibly synthesized.
  3. As zeolites are metastable, certain frameworks may be inaccessible as nucleation cannot occur because more stable and energetically favorable zeolites will form. Post-synthetic modification has been used to combat this issue with the ADOR method, whereby frameworks can be cut apart into layers and bonded back together by either removing silica bonds or including them.

Zeolites are widely used as ion-exchange beds in domestic and commercial water purification, softening, and other applications. Earlier, polyphosphates were used to soften hard water. The polyphosphates forms complex with metal ions like Ca2+ and Mg2+ to bind them up so that they could not interfere in cleaning process. However, when this phosphate rich water goes in main stream water, it results in eutrophication of water bodies and hence use of polyphosphate was replaced with use of a synthetic zeolite. In chemistry, zeolites are used to separate molecules (only molecules of certain sizes and shapes can pass through), and as traps for molecules so they can be analyzed.

Zeolites are also widely used as catalysts and sorbents. Their well-defined pore structure and adjustable acidity make them highly active in a large variety of reactions.

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. Other separations include noble gases, N2, O2, freon, and formaldehyde.

Zeolites were discovered to help silver naturally emit light, which may compete with fluorescent lights or LEDs.

On-board oxygen generating systems (OBOGS) and oxygen concentrators use zeolites in conjunction with pressure swing adsorption to remove nitrogen from compressed air to supply oxygen for aircrews at high altitudes, as well as home and portable oxygen supplies.

Industry

Synthetic zeolites, like other mesoporous materials (e.g., MCM-41), are widely used as catalysts in the petrochemical industry, such as in fluid catalytic cracking and hydrocracking. Zeolites confine molecules into small spaces, which causes changes in their structure and reactivity. The acidic forms of zeolites prepared are often powerful solid-state solid acids, facilitating a host of acid-catalyzed reactions, such as isomerization, alkylation, and cracking.

Catalytic cracking uses a reactor and a regenerator. Feed is injected onto a hot, fluidized catalyst where large gasoil molecules are broken into smaller gasoline molecules and olefins. The vapor-phase products are separated from the catalyst and distilled into various products. The catalyst is circulated to a regenerator, where the air is used to burn coke off the surface of the catalyst that was formed as a byproduct in the cracking process. The hot, regenerated catalyst is then circulated back to the reactor to complete its cycle.

Zeolites have used advanced nuclear-waste reprocessing methods, where their micro-porous ability to capture some ions while allowing others to pass freely allows many fission products to be efficiently removed from the 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. Zeolites are also used in the management of leaks of radioactive materials. For example, in the aftermath of the Fukushima Daiichi nuclear disaster, sandbags of zeolite were dropped into the seawater near the power plant to adsorb the radioactive cesium that was present in high levels.

The German group Fraunhofer e.V. announced that they had developed a zeolite substance for use in the biogas industry for long-term storage of energy at a density four times greater than water.[non-primary source needed] Ultimately, the goal is to store heat both in industrial installations and in small combined heat and power plants such as those used in larger residential buildings.

Solar energy storage and use

Zeolites can be used to thermochemically store solar heat harvested from solar thermal collectors as first demonstrated by Guerra in 1978 and for adsorption refrigeration, as first demonstrated by Tchernev in 1974. 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 (energy releasing) reaction when transitioning from a dehydrated form to a hydrated form make natural zeolites useful in harvesting waste heat and solar heat energy.[non-primary source needed]

Commercial and domestic

Zeolites are also used as a molecular sieve in cryosorption style vacuum pumps.

The largest single use for zeolite is the global laundry detergent market. Zeolites are used in laundry detergent as water softeners, removing Ca2+ and Mg2+ ions which would otherwise precipitate from the solution. The ions are retained by the zeolites which releases Na+ ions into the solution, allowing the laundry detergent to be effective in areas with hard water.

Non-clumping cat litter is often made of zeolite or diatomite.

Synthetic zeolites are used as an additive in the production process of warm mix asphalt concrete. The development of this application started in Germany in the 1990s. They help 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 vapors. The use of synthetic zeolites 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, they can reduce chloride permeability and improve workability. They reduce weight and help moderate water content while allowing for slower drying, which improves break strength. When added to lime mortars and lime-metakaolin mortars, synthetic zeolite pellets can act simultaneously as a pozzolanic material and a water reservoir.

Debbie Meyer Green Bags, a produce storage and preservation product, uses a form of zeolite as its active ingredient. The bags are lined with zeolite to adsorb ethylene, which is intended to slow the ripening process and extend the shelf life of produce stored in the bags.

Gemstones

Polished thomsonite

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. Thomsonite nodules from these areas have eroded from basalt lava flows and are collected on beaches and by scuba divers in Lake Superior.

These thomsonite nodules have concentric rings in combinations of colors: black, white, orange, pink, purple, red, and many shades of green. Some nodules have copper inclusions and rarely will be found with copper "eyes". When polished by a lapidary, the thomsonites sometimes displays a "cat's eye" effect (chatoyancy).

Biological

Animation of pressure swing adsorption, (1) and (2) showing alternating adsorption and desorption
I compressed air input A adsorption
O oxygen output D desorption
E exhaust

Research into and development of the many biochemical and biomedical applications of zeolites, particularly the naturally occurring species heulandite, clinoptilolite, and chabazite has been ongoing.

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 adsorption of nitrogen, leaving highly purified oxygen and up to 5% argon.

QuikClot brand hemostatic agent, which is used to stop severe bleeding, contains a calcium-loaded form of zeolite found in kaolin clay.

In agriculture, clinoptilolite (a naturally occurring zeolite) is used as a soil treatment. It provides a source of slowly released potassium. If previously loaded with ammonium, the zeolite can serve a similar function in the slow release of nitrogen. 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 the plant's demand. This property can prevent root rot and moderate drought cycles.

Clinoptilolite has also been added to chicken food: the absorption of water and ammonia by the zeolite made the birds' droppings drier and less odoriferous, hence easier to handle.

Pet stores market zeolites for use as filter additives in aquaria, where they can be used to adsorb ammonia and other nitrogenous compounds. They must be used with some care, especially with delicate tropical corals that are sensitive to water chemistry and temperature. 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 also 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 aquarium applications. Most Northern hemisphere, natural zeolites were formed when molten lava came into contact with sea water, thereby "loading" the zeolite with Na (sodium) sacrificial ions. The mechanism is well known to chemists as ion exchange. These sodium ions can be replaced by other ions in solution, thus the take-up of nitrogen in ammonia, with the release of the sodium. A deposit near Bear River in southern Idaho is a fresh water variety (Na < 0.05%). Southern hemisphere zeolites are typically formed in freshwater and have a high calcium content.

A combination specimen of four zeolite species. The radiating natrolite crystals are protected in a pocket with associated stilbite. The matrix around and above the pocket is lined with small, pink-colored laumontite crystals. Heulandite is also present as a crystal cluster on the backside

The zeolite structural group (Nickel-Strunz classification) includes:

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Zeolite
Zeolite Language Watch Edit Zeolites are microporous aluminosilicate minerals commonly used as commercial adsorbents and catalysts 1 The term zeolite was originally coined in 1756 by Swedish mineralogist Axel Fredrik Cronstedt who observed that rapidly heating a material believed to have been stilbite produced large amounts of steam from water that had been adsorbed by the material Based on this he called the material zeolite from the Greek zew zeō meaning to boil and li8os lithos meaning stone 2 The classic reference for the field has been Breck s book Zeolite Molecular Sieves Structure Chemistry And Use 3 Zeolites occur naturally but are also produced industrially on a large scale As of December 2018 update 253 unique zeolite frameworks have been identified and over 40 naturally occurring zeolite frameworks are known 4 5 Every new zeolite structure that is obtained is examined by the International Zeolite Association Structure Commission and receives a three letter designation 6 Contents 1 Properties and occurrence 2 Production 2 1 Natural occurrence 2 2 Artificial synthesis 2 3 The zeolite conundrum 3 Uses of zeolites 3 1 Industry 3 2 Solar energy storage and use 3 3 Commercial and domestic 3 4 Gemstones 3 5 Biological 4 Zeolite mineral species 5 See also 6 References 7 Further reading 8 External linksProperties and occurrence Edit A form of thomsonite one of the rarest zeolites from India Microscopic structure of a zeolite mordenite framework assembled from SiO 4 displaystyle ce SiO 4 tetrahedra Sodium is present as an extra framework cation in green Zeolites have a porous structure that can accommodate a wide variety of cations such as Na K Ca2 Mg2 and others 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 clinoptilolite heulandite natrolite phillipsite and stilbite An example of the mineral formula of a zeolite is Na2 Al2 Si3 O10 2H2O the formula for natrolite Cation exchanged zeolites possess different acidity and catalyse different reactions 7 8 9 non primary source needed Natural zeolites form where volcanic rocks and ash layers react with alkaline groundwater Zeolites also crystallize 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 citation needed Zeolites are the aluminosilicate members of the family of microporous solids known as molecular sieves and mainly consist of silicon aluminum oxygen and have the general formula MxAlxSi1 xO2 yH2O where M is either a metal ion or H The value of x is between 0 and 1 and y is the number of water molecules in the formula unit Although there are a wide range of possible structures a commonality is that they are formed by the linking of the corner oxygen atoms of AlO4 and SiO4 tetrahedra to form covalent network structures 10 The term molecular sieve refers to a particular property of these materials i 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 dimensions of the channels These are conventionally defined by the ring size of the aperture where for example the term eight ring refers to a closed loop that is built from eight tetrahedrally coordinated silicon or aluminum atoms and eight oxygen atoms These rings are not always perfectly symmetrical due to a variety of causes 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 pores in many zeolites are not cylindrical Zeolites transform to other minerals under weathering hydrothermal alteration or metamorphic conditions Some examples 11 The sequence of silica rich volcanic rocks commonly progresses from Clay quartz mordenite heulandite epistilbite stilbite thomsonite mesolite scolecite chabazite calcite citation needed The sequence of silica poor volcanic rocks commonly progresses from Cowlesite levyne offretite analcime thomsonite mesolite scolecite chabazite calcite Production EditIndustrially important zeolites are produced synthetically Typical procedures entail heating aqueous solutions of alumina and silica with sodium hydroxide Equivalent reagents include sodium aluminate and sodium silicate Further variations include the use of structure directing agents SDA such as quaternary ammonium cations 12 Synthetic zeolites hold some key advantages over their natural analogs The synthetic materials are manufactured in a uniform phase pure state It is also possible to produce zeolite structures that 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 Natural occurrence Edit Natrolite from Poland Conventional open pit mining techniques are used to mine natural zeolites 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 As of 2016 update the world s annual production of natural zeolite approximates 3 million tonnes Major producers in 2010 included China 2 million tonnes South Korea 210 000 t Japan 150 000 t Jordan 140 000 t Turkey 100 000 t Slovakia 85 000 t and the United States 59 000 t 13 The ready availability of zeolite rich rock at low cost and the shortage of competing minerals and rocks are probably the most important factors for its large scale use According to the United States Geological Survey it is likely that a significant percentage of the material sold as zeolites in some countries is ground or sawn volcanic tuff that contains only a small amount of zeolites Some examples of such usage include dimension stone as an altered volcanic tuff lightweight aggregate pozzolanic cement and soil conditioners 14 Artificial synthesis Edit Synthetic zeolite There are over 200 synthetic zeolites that have been synthesized by a process of slow crystallization of a silica alumina gel in the presence of alkalis and organic templates Many more such structures could theoretically be made 15 In addition to variations in structures zeolites can also be made with a variety of other atoms in them to make them chemically interesting and active Some examples of the so called heteroatoms that have been incorporated include germanium iron gallium boron zinc tin and titanium 16 One of the important processes used to carry out zeolite synthesis is sol gel processing 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 the sol gel process other elements metals metal oxides can be easily incorporated The silicalite sol formed by the hydrothermal method is very stable The ease of scaling up this process makes it a favored route for zeolite synthesis The zeolite conundrum Edit Computer calculations have predicted that millions of hypothetical zeolite structures are possible However only 232 of these structures have been discovered and synthesized so far so many zeolite scientists question why only this small fraction of possibilities are being observed This problem is often referred to as the bottleneck problem citation needed Currently several theories are attempting to explain the reasoning behind this question Zeolite synthesis research has primarily been concentrating on hydrothermal methods however new zeolites may be synthesized using alternative methods Synthesis methods that have started to gain use include microwave assisted post synthetic modification steam Geometric computer simulations have shown that the discovered zeolite frameworks possess a behavior known as the flexibility window This shows that there is a range in which the zeolite structure is flexible and can be compressed but retain the framework structure It is suggested that if a framework does not possess this property then it cannot be feasibly synthesized As zeolites are metastable certain frameworks may be inaccessible as nucleation cannot occur because more stable and energetically favorable zeolites will form Post synthetic modification has been used to combat this issue with the ADOR method 17 whereby frameworks can be cut apart into layers and bonded back together by either removing silica bonds or including them Uses of zeolites EditZeolites are widely used as ion exchange beds in domestic and commercial water purification softening and other applications Earlier polyphosphates were used to soften hard water The polyphosphates forms complex with metal ions like Ca2 and Mg2 to bind them up so that they could not interfere in cleaning process However when this phosphate rich water goes in main stream water it results in eutrophication of water bodies and hence use of polyphosphate was replaced with use of a synthetic zeolite In chemistry zeolites are used to separate molecules only molecules of certain sizes and shapes can pass through and as traps for molecules so they can be analyzed Zeolites are also widely used as catalysts and sorbents Their well defined pore structure and adjustable acidity make them highly active in a large variety of reactions 18 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 Other separations include noble gases N2 O2 freon and formaldehyde Zeolites were discovered to help silver naturally emit light which may compete with fluorescent lights or LEDs 19 On board oxygen generating systems OBOGS and oxygen concentrators use zeolites in conjunction with pressure swing adsorption to remove nitrogen from compressed air to supply oxygen for aircrews at high altitudes as well as home and portable oxygen supplies 20 Industry Edit Synthetic zeolites like other mesoporous materials e g MCM 41 are widely used as catalysts in the petrochemical industry such as in fluid catalytic cracking and hydrocracking Zeolites confine molecules into small spaces which causes changes in their structure and reactivity The acidic forms of zeolites prepared are often powerful solid state solid acids facilitating a host of acid catalyzed reactions such as isomerization alkylation and cracking Catalytic cracking uses a reactor and a regenerator Feed is injected onto a hot fluidized catalyst where large gasoil molecules are broken into smaller gasoline molecules and olefins The vapor phase products are separated from the catalyst and distilled into various products The catalyst is circulated to a regenerator where the air is used to burn coke off the surface of the catalyst that was formed as a byproduct in the cracking process The hot regenerated catalyst is then circulated back to the reactor to complete its cycle Zeolites have used advanced nuclear waste reprocessing methods where their micro porous ability to capture some ions while allowing others to pass freely allows many fission products to be efficiently removed from the 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 Zeolites are also used in the management of leaks of radioactive materials For example in the aftermath of the Fukushima Daiichi nuclear disaster sandbags of zeolite were dropped into the seawater near the power plant to adsorb the radioactive cesium that was present in high levels 21 The German group Fraunhofer e V announced that they had developed a zeolite substance for use in the biogas industry for long term storage of energy at a density four times greater than water 22 non primary source needed Ultimately the goal is to store heat both in industrial installations and in small combined heat and power plants such as those used in larger residential buildings Solar energy storage and use Edit Zeolites can be used to thermochemically store solar heat harvested from solar thermal collectors as first demonstrated by Guerra in 1978 23 and for adsorption refrigeration as first demonstrated by Tchernev in 1974 24 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 energy releasing reaction when transitioning from a dehydrated form to a hydrated form make natural zeolites useful in harvesting waste heat and solar heat energy non primary source needed Commercial and domestic Edit Zeolites are also used as a molecular sieve in cryosorption style vacuum pumps 25 The largest single use for zeolite is the global laundry detergent market Zeolites are used in laundry detergent as water softeners removing Ca2 and Mg2 ions which would otherwise precipitate from the solution The ions are retained by the zeolites which releases Na ions into the solution allowing the laundry detergent to be effective in areas with hard water 10 Non clumping cat litter is often made of zeolite or diatomite Synthetic zeolites are used as an additive in the production process of warm mix asphalt concrete The development of this application started in Germany in the 1990s They help 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 vapors The use of synthetic zeolites 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 they can reduce chloride permeability and improve workability They reduce weight and help moderate water content while allowing for slower drying which improves break strength 26 When added to lime mortars and lime metakaolin mortars synthetic zeolite pellets can act simultaneously as a pozzolanic material and a water reservoir 27 28 Debbie Meyer Green Bags a produce storage and preservation product uses a form of zeolite as its active ingredient The bags are lined with zeolite to adsorb ethylene which is intended to slow the ripening process and extend the shelf life of produce stored in the bags Gemstones Edit Polished thomsonite 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 Thomsonite nodules from these areas have eroded from basalt lava flows and are collected on beaches and by scuba divers in Lake Superior These thomsonite nodules have concentric rings in combinations of colors black white orange pink purple red and many shades of green Some nodules have copper inclusions and rarely will be found with copper eyes When polished by a lapidary the thomsonites sometimes displays a cat s eye effect chatoyancy 29 Biological Edit Animation of pressure swing adsorption 1 and 2 showing alternating adsorption and desorption I compressed air input A adsorption O oxygen output D desorption E exhaust Research into and development of the many biochemical and biomedical applications of zeolites particularly the naturally occurring species heulandite clinoptilolite and chabazite has been ongoing 30 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 adsorption of nitrogen leaving highly purified oxygen and up to 5 argon QuikClot brand hemostatic agent which is used to stop severe bleeding 31 contains a calcium loaded form of zeolite found in kaolin clay 32 In agriculture clinoptilolite a naturally occurring zeolite is used as a soil treatment It provides a source of slowly released potassium If previously loaded with ammonium the zeolite can serve a similar function in the slow release of nitrogen 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 the plant s demand This property can prevent root rot and moderate drought cycles Clinoptilolite has also been added to chicken food the absorption of water and ammonia by the zeolite made the birds droppings drier and less odoriferous hence easier to handle 33 Pet stores market zeolites for use as filter additives in aquaria 14 where they can be used to adsorb ammonia and other nitrogenous compounds They must be used with some care especially with delicate tropical corals that are sensitive to water chemistry and temperature 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 also 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 aquarium applications Most Northern hemisphere natural zeolites were formed when molten lava came into contact with sea water thereby loading the zeolite with Na sodium sacrificial ions The mechanism is well known to chemists as ion exchange These sodium ions can be replaced by other ions in solution thus the take up of nitrogen in ammonia with the release of the sodium A deposit near Bear River in southern Idaho is a fresh water variety Na lt 0 05 34 Southern hemisphere zeolites are typically formed in freshwater and have a high calcium content 35 Zeolite mineral species Edit A combination specimen of four zeolite species The radiating natrolite crystals are protected in a pocket with associated stilbite The matrix around and above the pocket is lined with small pink colored laumontite crystals Heulandite is also present as a crystal cluster on the backside The zeolite structural group Nickel Strunz classification includes 4 11 36 37 38 09 GA Zeolites with T5O10 units T combined Si and Al the fibrous zeolites Natrolite framework NAT gonnardite natrolite mesolite paranatrolite scolecite tetranatrolite Edingtonite framework EDI edingtonite kalborsite Thomsonite framework THO thomsonite series 09 GB Chains of single connected 4 membered rings Analcime framework ANA analcime leucite pollucite wairakite Laumontite LAU yugawaralite YUG goosecreekite GOO montesommaite MON 09 GC Chains of doubly connected 4 membered rings Phillipsite framework PHI harmotome phillipsite series Gismondine framework GIS amicite gismondine garronite gobbinsite Boggsite BOG merlinoite MER mazzite series MAZ paulingite series PAU perlialite Linde type L framework zeolite L LTL 09 GD Chains of 6 membered rings tabular zeolites Chabazite framework CHA chabazite series herschelite willhendersonite and SSZ 13 Faujasite framework FAU faujasite series Linde type X zeolite X X zeolites Linde type Y zeolite Y Y zeolites Mordenite framework MOR maricopaite mordenite Offretite wenkite subgroup 09 GD 25 Nickel Strunz 10 ed offretite OFF wenkite WEN Bellbergite TMA E Aiello and Barrer framework type EAB bikitaite BIK erionite series ERI ferrierite FER gmelinite GME levyne series LEV dachiardite series DAC epistilbite EPI 09 GE Chains of T10O20 tetrahedra T combined Si and Al Heulandite framework HEU clinoptilolite heulandite series Stilbite framework STI barrerite stellerite stilbite series Brewsterite framework BRE brewsterite series Others Cowlesite pentasil also known as ZSM 5 framework type MFI tschernichite beta polymorph A disordered framework BEA Linde type A framework zeolite A LTA See also EditGeopolymer Polymeric Si O Al framework similar to zeolites but amorphous the amorphous alumino silicate equivalent of zeolite List of minerals List of minerals for which there are articles on Wikipedia Hypothetical zeolite Adsorption Science of surface adhesion Solid sorbents for carbon capture Pyrolysis Thermal decomposition of materials at elevated temperatures in an inert atmosphereReferences Edit Zeolite Structure GRACE com W R Grace amp Co 2006 Archived from the original on 15 February 2009 Retrieved 8 Feb 2019 Cronstedt AF 1756 Natural zeolite and minerals Svenska Vetenskaps Akademiens Handlingar Stockholm 17 120 Breck DW 1973 Zeolite molecular sieves structure chemistry and use Wiley ISBN 9780471099857 a b Database of Zeolite Structures iza structure org International Zeolite Association 2017 Retrieved 24 May 2021 Minerals Arranged by the New Dana Classification webmineral com Retrieved 8 Feb 2019 News from the Structure Commission IZA Structure Commission 2018 Retrieved 8 Feb 2018 Marakatti VS Halgeri AB 2015 Metal ion exchanged zeolites as highly active solid acid catalysts for the green synthesis of glycerol carbonate from glycerol RSC Adv 5 19 14286 14293 doi 10 1039 C4RA16052E ISSN 2046 2069 Marakatti VS Halgeri AB Shanbhag GV 2014 Metal ion exchanged zeolites as solid acid catalysts for the green synthesis of nopol from Prins reaction Catal Sci Technol 4 11 4065 4074 doi 10 1039 C4CY00596A ISSN 2044 4761 S2CID 94555012 Marakatti VS Rao PV Choudary NV et al 2014 Influence of Alkaline Earth Cation Exchanged X Zeolites Towards Ortho Selectivity in Alkylation of Aromatics Hard Soft Acid Base Concept Advanced Porous Materials 2 4 221 229 9 doi 10 1166 apm 2014 1079 a b Chemistry3 introducing inorganic organic and physical chemistry Andrew Burrows Oxford Oxford University Press 2009 p 253 ISBN 978 0 19 927789 6 OCLC 251213960 CS1 maint others link a b Tschernich RW 1992 Zeolites of the World Geoscience Press ISBN 9780945005070 Rollmann LD Valyocsik EW Shannon RD 1995 Zeolite Molecular Sieves In Murphy DW Interrante LV eds Inorganic Syntheses Nonmolecular Solids Inorganic Syntheses 30 New York Wiley amp Sons pp 227 234 doi 10 1002 9780470132616 ch43 ISBN 9780470132616 Zeolites natural PDF USGS Mineral Commodity Summaries 2011 Retrieved 8 Feb 2019 a b Virta RL 2011 2009 Minerals Yearbook Zeolites PDF USGS Retrieved 8 Feb 2019 Earl DJ Deem MW 2006 Toward a Database of Hypothetical Zeolite Structures Ind Eng Chem Res 45 16 5449 5454 doi 10 1021 ie0510728 ISSN 0888 5885 Szostak R 1998 Molecular Sieves Principles of Synthesis and Identification Van Nostrand Reinhold Electrical Computer Science and Engineering Series Springer ISBN 9780751404807 Roth WJ Nachtigall P Morris RE et al 2013 A family of zeolites with controlled pore size prepared using a top down method Nat Chem 5 7 628 633 Bibcode 2013NatCh 5 628R doi 10 1038 nchem 1662 hdl 10023 4529 ISSN 1755 4330 PMID 23787755 Bhatia S 1989 Zeolite Catalysts Principles and Applications Boca Raton CRC Press ISBN 9780849356285 Scientists discover why silver clusters emit light 2018 Retrieved 25 Jan 2021 On Board Oxygen Generating System OBOGS Honeywell com Honeywell International Inc Archived from the original on 10 September 2011 Retrieved 9 Feb 2019 The Associated Press 16 Apr 2011 Level of Radioactive Materials Rises Near Japan Plant NYTimes ISSN 0362 4331 Compact and flexible thermal storage Fraunhofer Research News Fraunhofer Gesellschaft 1 Jun 2012 U S Pat No 4 269 170 Adsorption Solar Heating and Storage System Filed April 27 1978 Inventor John M Guerra U S Patent No 4 034 569 Filed Nov 4 1974 Inventor Dimiter I Tchernev Ventura G Risegari L 2007 The Art of Cryogenics Low Temperature Experimental Techniques Elsevier p 17 ISBN 9780080444796 Dypayan J 2007 Clinoptilolite a promising pozzolan in concrete PDF A New Look at an Old Pozzolan 29th ICMA Conference Quebec City Canada Construction Materials Consultants Inc pp 168 206 Retrieved 7 Oct 2013 Andrejkovicova S Ferraz E Velosa AL et al 2012 Air Lime Mortars with Incorporation of Sepiolite and Synthetic Zeolite Pellets PDF Acta Geodynamica et Geomaterialia 9 1 79 91 Ferraza E Andrejkovicova S Velosa AL et al 2014 Synthetic zeolite pellets incorporated to air lime metakaolin mortars mechanical properties Construction amp Building Materials 69 243 252 doi 10 1016 j conbuildmat 2014 07 030 Dietrich RV 2005 Thomsonite GemRocks Retrieved 2 Oct 2013 Auerbach SM Carrado KA Dutta PK eds 2003 Handbook of Zeolite Science and Technology Boca Raton CRC Press p 16 ISBN 9780824740207 Rhee P Brown C Martin M et al 2008 QuikClot use in trauma for hemorrhage control case series of 103 documented uses J Trauma 64 4 1093 9 doi 10 1097 TA 0b013e31812f6dbc PMID 18404080 S2CID 24827908 Rowe A 2018 Nanoparticles Help Gauze Stop Gushing Wounds Wired Conde Nast Retrieved 1 Nov 2013 Mumpton FA 1985 Ch VIII Using Zeolites in Agriculture PDF In Elfring C ed Innovative Biological Technologies for Lesser Developed Countries Washington DC US Congress Office of Technology Assessment LCCN 85600550 Hongting Z Vance GF Ganjegunte GK et al 2008 Use of zeolites for treating natural gas co produced waters in Wyoming USA Desalination 228 1 3 263 276 doi 10 1016 j desal 2007 08 014 Wang Shaobin Peng Yuelian 2009 10 09 Natural zeolites as effective adsorbents in water amp wastewater treatment PDF Chemical Engineering Journal 156 1 11 24 doi 10 1016 j cej 2009 10 029 Retrieved 2019 07 13 Database of Mineral Properties IMA Retrieved 9 Feb 2019 Nickel Strunz Classification Primary Groups 10th ed mindat org Retrieved 10 Feb 2019 First EL Gounaris CE Wei J et al 2011 Computational characterization of zeolite porous networks An automated approach Phys Chem Chem Phys 13 38 17339 17358 Bibcode 2011PCCP 1317339F doi 10 1039 C1CP21731C PMID 21881655 This article incorporates public domain material from the United States Geological Survey document Zeolites PDF Further reading EditSheppard RA 1973 Zeolites in Sedimentary Rocks In Brobst DA Pratt WP eds United States mineral resources Professional Paper 820 Washington DC USGS pp 689 695 doi 10 3133 pp820 Clifton RA 1987 Natural and Synthetic Zeolites Information Circular 9140 Pittsburgh USBM OCLC 14932428 Mumpton FA 1999 La roca magica Uses of natural zeolites in agriculture and industry PNAS 96 7 3463 3470 Bibcode 1999PNAS 96 3463M doi 10 1073 pnas 96 7 3463 PMC 34179 PMID 10097058 Monnier JB Dupont M 1983 Zeolite water close cycle solar refrigeration numerical optimisation and field testing Proc Annu Meet Am Sect Int Sol Energy Soc 6 181 185 OSTI 5126636 American Solar Energy Society meeting 1 Jun 1983 Minneapolis MN USA CS1 maint postscript link Newsam JM 1992 Zeolites In Cheetham AK Day P eds Solid State Chemistry 2 Clarendon Press ISBN 9780198551669 Rhodes CJ 2007 Zeolites Physical Aspects and Environmental Applications Annu Rep Prog Chem C 103 287 325 doi 10 1039 b605702k External links EditWikimedia Commons has media related to Zeolite Scholia has a topic profile for Zeolite International Zeolite Association Database of zeolite pore characterizations The Synthesis Commission of the International Zeolite Association Federation of European Zeolite Associations British Zeolite Association Database of Zeolite Structures Retrieved from https en wikipedia org w index php title Zeolite amp oldid 1053800161, wikipedia, wiki, book,

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