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52-604: GVL may refer to: gamma -Valerolactone Grand Valley Lanthorn , the student newspaper of Grand Valley State University Gesellschaft zur Verwertung von Leistungsschutzrechten , a German copyright collection society Gudlavalleru railway station , in Andhra Pradesh, India Gulay language Lee Gilmer Memorial Airport , in Gainesville, Georgia, United States Greenville, South Carolina Global VM lock , also known as

104-413: A lapidary , the thomsonites sometimes displays a "cat's eye" effect ( chatoyancy ). The first synthetic structure was reported by Richard Barrer . 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

156-473: 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. Non-clumping cat litter is often made of zeolite (or diatomite ), one form of which, invented at MIT , can sequester

208-560: A 10-ring are called medium pore zeolites , a typical example being ZSM-5 (MFI). Although more than 200 types of zeolites are known, only about 100 types of aluminosilicate are available. In addition, there are only a few types that can be synthesized in industrially feasible way and have sufficient thermal stability to meet the requirements for industrial use. In particular, the FAU (faujasite, USY), BEA (beta), MOR (high-silica mordenite), MFI (ZSM-5), and FER (high-silica ferrierite) types are called

260-495: A high calcium content. The zeolite structural group ( Nickel-Strunz classification ) includes: 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 observed. This problem is often referred to as "the bottleneck problem". Currently, several theories attempt to explain

312-540: A legal substitute for GHB. GVL is produced from levulinic acid , which is obtained from hexoses . In a typical process, cellulosic biomasses , such as corn stover , sawgrass , or wood, is hydrolysed into glucose and other sugars using acid catalysts . The resulting glucose can then be dehydrated via hydroxymethylfurfural to yield formic acid and levulinic acid , which cyclises to intermediate unsaturated ring compounds , which can then be hydrogenated to gamma -valerolactone, which has potential applications as

364-631: A liquid fuel. GVL has been identified as a potential green solvent. Because of its herbal odor, it is used in the perfume and flavor industries. It is a structural isomer of δ-valerolactone . Since it is readily obtained from glucose, GVL has long been identified as a potential "green fuel." GVL retains 97% of the energy of glucose and can be blended by itself in gasoline where it performs comparably to ethanol /gasoline mixtures. However, due to blending limits for use in conventional combustion engines, it may be more efficient to convert GVL into liquid alkenes (or alkanes ). The first step in this process

416-405: 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

468-576: A three-letter designation. Zeolites are white solids with ordinary handling properties, like many routine aluminosilicate minerals, e.g. feldspar . They have the general formula (MAlO 2 )(SiO 2 ) x (H 2 O) y where M is usually H and Na . The Si/Al ratio is variable, which provides a means to tune the properties. Zeolites with a Si/Al ratios higher than about 3 are classified as high-silica zeolites , which tend to be more hydrophobic. The H and Na can be replaced by diverse cations, because zeolites have ion exchange properties. The nature of

520-473: 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-137 that was present in high levels. Zeolites have

572-404: Is called four membered ring or simply four-ring . The figure on the right shows a 4-ring with Si atoms connected to each other, which is the most common way to express the topology of the framework. The figure on the right compares the typical framework structures of LTA (left) and FAU (right). Both zeolites share the truncated octahedral structure ( sodalite cage) (purple line). However,

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624-406: Is different from Wikidata All article disambiguation pages All disambiguation pages Gamma-Valerolactone GVL behaves as a prodrug to γ-hydroxyvaleric acid (GHV), a drug with similar effects to those of γ-hydroxybutyric acid (GHB), albeit with less potency in comparison. Because GHB is controlled in many parts of the world, while GVL is not, GVL has gained popularity as

676-457: 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. 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

728-1060: Is isomorphous with Al and P and Al is isomorphous with Si, and the gallogermanate and others are known. 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 ·2H 2 O, the formula for natrolite . 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. Zeolites transform to other minerals under weathering , hydrothermal alteration or metamorphic conditions. Some examples: Thomsonites , one of

780-596: Is strong enough to protonate hydrocarbons and high-silica zeolites are used in acid catalysis processes such as fluid catalytic cracking in petrochemical industry. The structures of hundreds of zeolites have been determined. Most do not occur naturally. For each structure, the International Zeolite Association (IZA) gives a three-letter code called framework type code (FTC). For example, the major molecular sieves, 3A, 4A and 5A, are all LTA (Linde Type A). Most commercially available natural zeolites are of

832-446: Is the ring-opening of GVL to yield a mixture of pentenoic acids . These acids can then be decarboxylated to produce butene and CO 2 . These conversions can be performed with zeolite catalysts. After this stream is dehydrated, the products can be oligomerized at elevated pressures in the presence of a common acid-catalyst to yield alkenes with higher molecular weights , targeted for gasoline and other fuel applications. One of

884-421: 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. 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. Ultimately,

936-568: 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. Pet stores market zeolites for use as filter additives in aquaria , where they can be used to adsorb ammonia and other nitrogenous compounds. Due to

988-407: The big five of high silica zeolites, and industrial production methods have been established. 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

1040-411: The greenhouse gas methane from the atmosphere. The original formulation of QuikClot brand hemostatic agent , which is used to stop severe bleeding, contained zeolite granules. When in contact with blood, the granules would rapidly absorb water from the blood plasma, creating an exothermic reaction which generated heat. The absorption of water would also concentrate clotting factors present within

1092-404: 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

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1144-401: 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

1196-516: The Corriental reservoir at the Maya city of Tikal , in northern Guatemala. Earlier, polyphosphates were used to soften hard water. The polyphosphates forms complex with metal ions like Ca and Mg 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

1248-529: The Global interpreter lock, in interpreter programs Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title GVL . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=GVL&oldid=1191915032 " Category : Disambiguation pages Hidden categories: Short description

1300-502: The MOR, HEU or ANA-types. An example of the notation of the ring structure of zeolite and other silicate materials is shown in the upper right figure. The middle figure shows a common notation using structural formula . The left figure emphasizes the SiO 4 tetrahedral structure. Connecting oxygen atoms together creates a four-membered ring of oxygen (blue bold line). In fact, such a ring substructure

1352-483: The ability to generate voids within the solid material – underpins the ability of zeolites to function as catalysts. They possess high physical and chemical stability due to the large covalent bonding contribution. They have excellent hydrophobicity and are suited for adsorption of bulky, hydrophobic molecules such as hydrocarbons. In addition to that, high-silica zeolites are H exchangeable, unlike natural zeolites, and are used as solid acid catalysts . The acidity

1404-638: The bags. 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. Zeolites are also used as a molecular sieve in cryosorption style vacuum pumps . 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

1456-456: The blood, causing the clot formation process to occur much faster than under normal circumstances, as shown in vitro . The 2022 formulation of QuikClot uses a nonwoven material impregnated with kaolin , an inorganic mineral activating Factor XII , in turn accelerating natural clotting. Unlike the original zeolite formulation, kaolin does not exhibit any thermogenic properties. In agriculture, clinoptilolite (a naturally occurring zeolite)

1508-512: 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. Isomorphous substitution of Si in zeolites can be possible for some heteroatoms such as titanium , zinc and germanium . Al atoms in zeolites can be also structurally replaced with boron and gallium . The silicoaluminophosphate type (AlPO molecular sieve), in which Si

1560-443: The cations influences the porosity of zeolites. Zeolites have microporous structures with a typical diameter of 0.3–0.8 nm. Like most aluminosilicates, the framework is formed by linking of aluminum and silicon atoms by oxides. This linking leads to a 3-dimensional network of Si-O-Al, Si-O-Si, and Al-O-Al linkages. The aluminum centers are negatively charged, which requires an accompanying cation. These cations are hydrated during

1612-532: The cracking process. The hot, regenerated catalyst is then circulated back to the reactor to complete its cycle. Zeolites containing cobalt nanoparticles have applications in the recycling industry as a catalyst to break down polyethylene and polypropylene , two widely used plastics, into propane . Zeolites have been used in advanced nuclear 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

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1664-512: The fabrication of polymeric membranes. Due to the toxicity of the traditional solvents, green solvents were investigated in recent years. Due to its environmentally friendly profile, gamma-valerolactone showed the potential to fabricate polysulfone membranes as a co-solvent. Zeolite Zeolite is a family of several microporous , crystalline aluminosilicate materials commonly used as commercial adsorbents and catalysts . They mainly consist of silicon , aluminium , oxygen , and have

1716-404: The formation of the materials. The hydrated cations interrupt the otherwise dense network of Si-O-Al, Si-O-Si, and Al-O-Al linkage, leading to regular water-filled cavities. Because of the porosity of the zeolite, the water can exit the material through channels. Because of the rigidity of the zeolite framework, the loss of water does not result in collapse of the cavities and channels. This aspect –

1768-429: The general formula M 1/n (AlO 2 ) (SiO 2 ) x ･y H 2 O where M 1/n is either a metal ion or H . The term 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

1820-424: 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. 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

1872-487: 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"

1924-419: The main advantages that allows GVL to be a practical biofuel is that it is relatively inexpensive to produce. Using a cheap feedstock , this biofuel can be produced at prices between 2-3 US$ /gallon. The conversion of GVL to transportation fuel capable alkenes only requires a system containing two flow reactors, two phase separators, and a simple pumping arrangement for the delivery of an aqueous GVL feed. Since

1976-427: The many biochemical and biomedical applications of zeolites, particularly the naturally occurring species heulandite , clinoptilolite , and chabazite has been ongoing. Zeolites are widely used as ion-exchange beds in domestic and commercial water purification , softening, and other applications. Evidence for the oldest known zeolite water purification filtration system occurs in the undisturbed sediments of

2028-622: The material zeolite , from the Greek ζέω (zéō) , meaning "to boil" and λίθος (líthos) , meaning "stone". Zeolites occur naturally, but are also produced industrially on a large scale. As of December 2018 , 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 (IZA-SC) and receives

2080-526: The most abundant mineral components on earth, the potential to supply zeolites is virtually unlimited. As of 2016 , 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

2132-413: 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 aluminium) atoms and eight oxygen atoms. These rings are not always perfectly symmetrical due to a variety of causes, including strain induced by

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2184-622: The potential of providing precise and specific separation of gases, including the removal of H 2 O, CO 2 , and SO 2 from low-grade natural gas streams. Other separations include noble gases , N 2 , O 2 , freon , and formaldehyde . 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. Zeolite-based oxygen concentrator systems are widely used to produce medical-grade oxygen. The zeolite

2236-711: 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

2288-416: The raw material, including lignins. The saccharide products can be recovered from the lactone into water solution by antisolvent addition of salt or liquid carbon dioxide. The product can be used as feedstock for producing furans or ethanol at high yield, while the gamma-valerolactone is returned to the catalytic cycle. Gamma-valerolactone has been studied and shown the potential to prepare dope solutions for

2340-877: 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. These materials are used for construction, e.g. dimension stone (as an altered volcanic tuff), lightweight aggregate , pozzolanic cement , and soil conditioners . Over 200 synthetic zeolites have been reported. Most zeolites have aluminosilicate frameworks but some incorporate germanium, iron, gallium, boron, zinc, tin, and titanium. Zeolite synthesis involves sol-gel -like processes. The product properties depend on reaction mixture composition, pH of

2392-479: 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. Zeolites are widely used as catalysts and sorbents . In chemistry, zeolites are used as membranes to separate molecules (only molecules of certain sizes and shapes can pass through), and as traps for molecules so they can be analyzed. Research into and development of

2444-563: The use of precious metal catalysts is not required, this also decreases the total price of fuel production. Apart from its value as a potential fuel in its own right, gamma-valerolactone has shown promise in laboratory-scale thermocatalytic production of soluble carbohydrates from corn stover and wood at high yields. The biomass reacts in a solvent mixture of water, dilute sulfuric acid, and gamma-valerolactone, itself derived from biomass. The gamma-valerolactone promotes thermocatalytic hydrolysis into monosaccharides by complete solubilization of

2496-448: 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

2548-423: 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

2600-496: The way they are connected (yellow line) is different: in LTA, the four-membered rings of the cage are connected to each other to form a skeleton, while in FAU, the six-membered rings are connected to each other. As a result, the pore entrance of LTA is an 8-ring (0.41 nm ) and belongs to the small pore zeolite , while the pore entrance of FAU is a 12-ring (0.74 nm ) and belongs to the large pore zeolite , respectively. Materials with

2652-403: 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

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2704-523: Was replaced with use of a synthetic zeolite. The largest single use for zeolite is the global laundry detergent market. Zeolites are used in laundry detergent as water softeners, removing Ca and Mg 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. Synthetic zeolites, like other mesoporous materials (e.g., MCM-41 ), are widely used as catalysts in

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