Editing Zeolite (section)

== Applications ==

Zeolites are widely used as catalysts and [[Sorbent|sorbents]].<ref>{{cite journal|author1=P. Chatterjee |author2=Y. Han |author3=T. Kobayashi |author4=K. Verma| author5=M. Mais| author6=R. Behera| author7=T. Johnson| author8=T. Prozorov| author9=J. Evans| author10=I.I. Slowing| author11=W. Huang|title=Capturing Rare-Earth Elements by Synthetic Aluminosilicate MCM-22: Mechanistic Understanding of Yb(III) Capture|journal= ACS Appl. Mater. Interfaces| year=2023|volume=15 |issue=46 |pages=54192–54201 |doi=10.1021/acsami.3c14560|pmid=37934618 |s2cid=265050410 }}</ref><ref>{{Cite book|url=https://books.google.com/books?id=x-vwPoX4YYkC|title=Zeolite Catalysts: Principles and Applications|last=Bhatia|first=Subhash|publisher=CRC Press|year=1989|isbn=9780849356285|location=Boca Raton|name-list-style=vanc}}</ref> In chemistry, zeolites are used as [[Zeolite membrane|membranes]] to separate [[molecule]]s (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 the many [[biochemical]] and [[biomedical]] applications of zeolites, particularly the naturally occurring species [[heulandite]], [[clinoptilolite]], and [[chabazite]] has been ongoing.<ref>{{Cite book|title=Handbook of Zeolite Science and Technology|publisher=CRC Press|year=2003|isbn=9780824740207|veditors=Auerbach SM, Carrado KA, Dutta PK|location=Boca Raton|pages=16}}</ref>

=== Ion-exchange, water purification and softening ===

Zeolites are widely used as [[ion-exchange]] beds in domestic and commercial [[water purification]], [[Water softening|softening]], and other applications.

Evidence for the oldest known zeolite water purification filtration system occurs in the undisturbed sediments of the Corriental reservoir at the Maya city of [[Tikal]], in northern Guatemala.<ref>Tankersley, K.B., Dunning, N.P., Carr, C. et al. Zeolite water purification at Tikal, an ancient Maya city in Guatemala. Sci Rep 10, 18021 (2020). https://doi.org/10.1038/s41598-020-75023-7</ref>

Earlier, polyphosphates were used to soften hard water. The polyphosphates forms complex with metal ions like Ca<sup>2+</sup> and Mg<sup>2+</sup> 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.

The largest single use for zeolite is the global laundry [[detergent]] market. Zeolites are used in laundry detergent as water softeners, removing Ca<sup>2+</sup> and Mg<sup>2+</sup> ions which would otherwise precipitate from the solution. The ions are retained by the zeolites which releases Na<sup>+</sup> ions into the solution, allowing the laundry detergent to be effective in areas with hard water.<ref name="Burrows-2009">{{Cite book |url=https://archive.org/details/chemistryintrodu0000burr/mode/2up |title=Chemistry3 : introducing inorganic, organic and physical chemistry|date=2009|publisher=Oxford University Press|author=Andrew Burrows |author2=John Holman |author3=Andrew Parsons |author4=Gwen Pilling |author5=Gareth Price |isbn=978-0-19-927789-6|location=Oxford|page=253|oclc=251213960}}</ref>

=== Catalysis ===

Synthetic zeolites, like other mesoporous materials (e.g., [[MCM-41]]), are widely used as [[catalyst]]s in the [[petrochemical industry]], such as in fluid catalytic [[Cracking (chemistry)|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 acid]]s, 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 containing cobalt [[nanoparticle]]s have applications in the recycling industry as a catalyst to break down [[polyethylene]] and [[polypropylene]], two widely used plastics, into [[propane]].<ref>{{Cite web |title=New process could enable more efficient plastics recycling |url=https://news.mit.edu/2022/plastics-recycling-cobalt-catalyst-1006 |access-date=2023-04-22 |website=MIT News {{!}} Massachusetts Institute of Technology |date=6 October 2022 |language=en}}</ref>

=== Nuclear waste reprocessing ===
[[File:U.S. Department of Energy - Science - 463 015 001 (10190451506).jpg|right|thumb|A researcher at [[Sandia National Laboratories]] examines vials of SOMS (Sandia Octahedral Molecular Sieve), a zeolite that shows potential for radioactive waste and industrial metals cleanup.]]

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 product]]s 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-137]] that was present in high levels.<ref>{{Cite news|url=https://www.nytimes.com/2011/04/17/world/asia/17nuke.html|title=Level of Radioactive Materials Rises Near Japan Plant|last=The Associated Press|date=16 Apr 2011|work=[[The New York Times|NYTimes]]|issn=0362-4331}}</ref>

===Gas separation and storage===
Zeolites have the potential of providing precise and specific separation of gases, including the removal of H<sub>2</sub>O, CO<sub>2</sub>, and SO<sub>2</sub> from low-grade [[natural gas]] streams. Other separations include [[noble gases]], N<sub>2</sub>, O<sub>2</sub>, [[freon]], and [[formaldehyde]].

On-board oxygen generating systems (OBOGS) and [[oxygen concentrator]]s 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.<ref>{{Cite web|url=http://www51.honeywell.com/aero/technology/trends3/solutions3/obogs.html?c=13|title=On-Board Oxygen Generating System (OBOGS)|website=Honeywell.com|publisher=Honeywell International Inc.|archive-url=https://web.archive.org/web/20110910220215/http://www51.honeywell.com/aero/technology/trends3/solutions3/obogs.html?c=13|archive-date=10 September 2011|url-status=dead|access-date=9 Feb 2019}}</ref>
[[File:pressure swing adsorption principle.svg|thumb|left|link={{filepath:pressure_swing_adsorption_principle.svg}}|Animation of pressure swing adsorption, (1) and (2) showing alternating adsorption and desorption
{|
!I
|compressed air input
|rowspan="3" width="3em"|
!A
|adsorption
|-
!O
|oxygen output
!D
|desorption
|-
!E
|exhaust
|}]]

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.

The German group [[Fraunhofer Society|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.<ref>{{Cite web|url=http://www.fraunhofer.de/en/press/research-news/2012/june/compact-and-flexible-thermal-storage.html|title=Compact and flexible thermal storage|date=1 Jun 2012|website=Fraunhofer Research News|publisher=Fraunhofer-Gesellschaft}}</ref>{{Primary source inline|date=August 2021}}<ref>{{Cite journal |last1=Pirsaheb |first1=Meghdad |last2=Hossaini |first2=Hiwa |last3=Amini |first3=Jila |date=2021 |title=Operational parameters influenced on biogas production in zeolite/anaerobic baffled reactor for compost leachate treatment |journal=Journal of Environmental Health Science & Engineering |volume=19 |issue=2 |pages=1743–1751 |doi=10.1007/s40201-021-00729-3 |pmc=8617091 |pmid=34900303|bibcode=2021JEHSE..19.1743P }}</ref><ref>{{Cite journal |last1=Druzyanova |first1=Varvara |last2=Petrova |first2=Sofya |last3=Khiterkheeva |first3=Nadezhda |last4=Bardamova |first4=Irina |last5=Gergenova |first5=Tatyana |date=2020 |editor-last=Rudoy |editor-first=D. |editor2-last=Ignateva |editor2-first=S. |title=The use of zeolites for biogas purification in agricultural production |journal=E3S Web of Conferences |volume=175 |pages=12012 |doi=10.1051/e3sconf/202017512012|doi-access=free |bibcode=2020E3SWC.17512012D }}</ref> 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.

[[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.

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.<ref>{{Cite book|title=Innovative Biological Technologies for Lesser Developed Countries|vauthors=Mumpton FA|publisher=US Congress, Office of Technology Assessment|year=1985|veditors=Elfring C|location=Washington, DC|chapter=Ch. VIII. Using Zeolites in Agriculture|lccn=85600550|chapter-url=https://www.princeton.edu/~ota/disk2/1985/8512/851210.PDF |archive-url=https://ghostarchive.org/archive/20221010/https://www.princeton.edu/~ota/disk2/1985/8512/851210.PDF |archive-date=2022-10-10 |url-status=live}}</ref>

Zeolites are also used as a [[molecular sieve]] in [[cryopump|cryosorption]] style [[vacuum pump]]s.<ref>{{cite book|url=https://books.google.com/books?id=4kvzBRUuGDkC&pg=PA17|title=The Art of Cryogenics: Low-Temperature Experimental Techniques|vauthors=Ventura G, Risegari L|publisher=Elsevier|year=2007|isbn=9780080444796|pages=17}}</ref>

===Solar energy storage and use===
Zeolites can be used to thermochemically store solar heat harvested from [[solar thermal collector]]s as first demonstrated by Guerra in 1978<ref>U.S. Pat. No. 4,269,170, "Adsorption Solar Heating and Storage System", Filed April 27, 1978, Inventor: John M. Guerra</ref> and for [[adsorption refrigeration]], as first demonstrated by Tchernev in 1974.<ref>U.S. Patent No. 4,034,569, Filed November 4, 1974, Inventor: Dimiter I. Tchernev</ref> 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.{{Primary source inline|date=August 2021}}

=== Building materials ===

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.<ref>{{cite conference|last=Dypayan J|year=2007|title=Clinoptilolite – a promising pozzolan in concrete|url=https://docs.wixstatic.com/ugd/df6185_396378e6da9840ba9de3cc2b39926a0e.pdf |archive-url=https://ghostarchive.org/archive/20221010/https://docs.wixstatic.com/ugd/df6185_396378e6da9840ba9de3cc2b39926a0e.pdf |archive-date=2022-10-10 |url-status=live|conference=29th ICMA Conference|location=Quebec City, Canada|publisher=Construction Materials Consultants, Inc.|pages=168–206|access-date=7 Oct 2013|book-title=A New Look at an Old Pozzolan}}</ref> When added to [[lime mortar]]s and lime-metakaolin mortars, synthetic zeolite pellets can act simultaneously as a pozzolanic material and a water reservoir.<ref name="air lime mortars">{{cite journal|display-authors=3|vauthors=Andrejkovičová S, Ferraz E, Velosa AL, Silva AS, Rocha F|year=2012|title=Air Lime Mortars with Incorporation of Sepiolite and Synthetic Zeolite Pellets|url=http://www.irsm.cas.cz/materialy/acta_content/2012_01/8_Andrejkovicova.pdf |archive-url=https://ghostarchive.org/archive/20221010/http://www.irsm.cas.cz/materialy/acta_content/2012_01/8_Andrejkovicova.pdf |archive-date=2022-10-10 |url-status=live|journal=Acta Geodynamica et Geomaterialia|volume=9|issue=1|pages=79–91}}</ref><ref name="air lime-metakaolin mortars">{{cite journal|display-authors=3|vauthors=Ferraza E, Andrejkovičová S, Velosa AL, Silva AS, Rocha F|year=2014|title=Synthetic zeolite pellets incorporated to air lime–metakaolin mortars: mechanical properties|url=http://repositorio.lnec.pt:8080/jspui/handle/123456789/1006428|journal=Construction & Building Materials|volume=69|pages=243–252|doi=10.1016/j.conbuildmat.2014.07.030}}</ref>

=== Cat litter ===

Non-clumping [[cat litter]] is often made of zeolite (or [[diatomite]]), one form of which, invented at [[MIT]], can sequester the [[greenhouse gas]] [[methane]] from the atmosphere.<ref>{{Cite news|url=https://www.wsj.com/articles/cat-litter-could-be-antidote-for-climate-change-researchers-say-11652490018|title=Cat Litter Could Be Antidote for Climate Change, Researchers Say|first=Ryan|last=Dezember|newspaper=WSJ |date=May 14, 2022|via=www.wsj.com}}</ref>

=== Hemostatic agent ===

The original formulation of [[QuikClot]] brand [[Hemostatic agents|hemostatic agent]], which is used to stop severe bleeding,<ref>{{Cite journal|display-authors=3|vauthors=Rhee P, Brown C, Martin M, Salim A, Plurad D, Green D, Chambers L, Demetriades D, Velmahos G, Alam H|year=2008|title=QuikClot use in trauma for hemorrhage control: case series of 103 documented uses|journal=The Journal of Trauma and Acute Care Surgery|volume=64|issue=4|pages=1093–9|doi=10.1097/TA.0b013e31812f6dbc|pmid=18404080|s2cid=24827908}}</ref> 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 the blood, causing the clot formation process to occur much faster than under normal circumstances, as shown [[in vitro]].<ref>{{Cite journal|display-authors=3 |last1=Li |first1=Jing |last2=Cao |first2=Wei |last3=Lv |first3=Xiao-xing |last4=Jiang |first4=Li |last5=Li |first5=Yue-jun |last6=Li |first6=Wang-zhou |last7=Chen |first7=Shao-zong |last8=Li |first8=Xue-yong |date=2013-03-01 |title=Zeolite-based hemostat QuikClot releases calcium into blood and promotes blood coagulation in vitro |journal=Acta Pharmacologica Sinica |volume=34 |issue=3 |pages=367–372 |doi=10.1038/aps.2012.159 |issn=1671-4083 |pmc=4002488 |pmid=23334236}}</ref>

The 2022 formulation of QuikClot uses a nonwoven material impregnated with [[Kaolinite|kaolin]], an inorganic mineral activating [[Factor XII]], in turn accelerating natural clotting.<ref>{{Cite web |title=QuikClot for Military {{!}} US Dept of Defense Hemostatic Dressing of Choice |url=https://quikclot.com/EN/Products/Military|date=2022 |access-date=2023-10-01 |publisher=Teleflex Inc.}}</ref> Unlike the original zeolite formulation, [[Kaolinite|kaolin]] does not exhibit any thermogenic properties.

=== Soil treatment ===
{{ multiple image
| image1   = LIFE ZEOWINE 1.jpg
| caption1 = Mixing composted waste matter from wine production with zeolites
| image2   = LIFE ZEOWINE 2.jpg
| caption2 = The microporous structure of the zeolites put into ground stabilizes water release and pH
}}

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.

=== Aquaria ===

Pet stores market zeolites for use as filter additives in [[aquarium|aquaria]],<ref name="Virta-2011" /> where they can be used to adsorb [[ammonia]] and other nitrogenous compounds. 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 (Great Salt Lake)|Bear River]] in southern [[Idaho]] is a fresh water variety (Na < 0.05%).<ref>{{cite journal|display-authors=3|vauthors=Hongting Z, Vance GF, Ganjegunte GK, Urynowicz MA|date=2008|title=Use of zeolites for treating natural gas co-produced waters in Wyoming, USA|journal=Desalination|volume=228|issue=1–3|pages=263–276|doi=10.1016/j.desal.2007.08.014|bibcode=2008Desal.228..263Z }}</ref> Southern hemisphere zeolites are typically formed in freshwater and have a high calcium content.<ref>{{cite journal|last1=Wang|first1=Shaobin|last2=Peng|first2=Yuelian|url=http://ida-ore.com/wp-content/uploads/2020/02/Wang_Natural-zealots-as-effective-absorbents.pdf |archive-url=https://ghostarchive.org/archive/20221010/http://ida-ore.com/wp-content/uploads/2020/02/Wang_Natural-zealots-as-effective-absorbents.pdf |archive-date=2022-10-10 |url-status=live|title=Natural zeolites as effective adsorbents in water & wastewater treatment|date=2009-10-09|journal=Chemical Engineering Journal|volume=156|issue=1|pages=11–24|doi=10.1016/j.cej.2009.10.029|access-date=2019-07-13}}</ref>

===Veterinary and human use===
Zeolites have some veterinary applications, with [[clinoptilolite]] approved in the EU as an additive for cattle feed.<ref>{{cite journal |title=Scientific Opinion on the safety and efficacy of clinoptilolite of sedimentary origin for all animal species: Clinoptilolite of sedimentary origin for all animal species |journal=EFSA Journal |date=January 2013 |volume=11 |issue=1 |pages=3039 |doi=10.2903/j.efsa.2013.3039}}</ref> It acts primarily as a detoxifying agent in the gut, where is can absorb undesirable species via ion-exchange before being excreted. For instance, nitrate fertilisers are water soluble and prolonged exposure by dairy cattle is known to impair protein metabolism and glucose utilization. Clinoptilolite adsorbs nitrate ions with good selectivity, allowing it to reduce these ill effects.<ref>{{cite journal |last1=Katsoulos |first1=P. D. |last2=Karatzia |first2=M. A. |last3=Polizopoulou |first3=Z. |last4=Florou-Paneri |first4=P. |last5=Karatzias |first5=H. |title=Effects of prolonged consumption of water with elevated nitrate levels on certain metabolic parameters of dairy cattle and use of clinoptilolite for their amelioration |journal=Environmental Science and Pollution Research |date=June 2015 |volume=22 |issue=12 |pages=9119–9126 |doi=10.1007/s11356-014-4060-8|pmid=25874417 |bibcode=2015ESPR...22.9119K }}</ref>

Zeolites have been studied for human medical applications,<ref>{{cite journal |last1=Kraljević Pavelić |first1=Sandra |last2=Simović Medica |first2=Jasmina |last3=Gumbarević |first3=Darko |last4=Filošević |first4=Ana |last5=Pržulj |first5=Nataša |last6=Pavelić |first6=Krešimir |title=Critical Review on Zeolite Clinoptilolite Safety and Medical Applications in vivo |journal=Frontiers in Pharmacology |date=27 November 2018 |volume=9 |page=1350 |doi=10.3389/fphar.2018.01350|doi-access=free |pmid=30538633 |pmc=6277462 }}</ref> particularly for bowel conditions.<ref>{{cite journal |last1=Mosgoeller |first1=Wilhelm |last2=Muss |first2=Claus |last3=Eisenwagen |first3=Sandra |last4=Jagsch |first4=Reinhold |last5=Vogelsang |first5=Harald |title=PMA – Zeolite (Clinoptilolite) in the Management of Irritable Bowel Syndrome – a Non-Interventional Study |journal=Zeitschrift für Gastroenterologie |date=March 2024 |volume=62 |issue=3 |pages=379–387 |doi=10.1055/a-2223-3963|pmid=38224685 |pmc=10914565 }}</ref><ref>{{cite journal |last1=Petkov |first1=V |last2=Schütz |first2=B |last3=Eisenwagen |first3=S |last4=Muss |first4=C |last5=Mosgoeller |first5=W |title=PMA-zeolite can modulate inflammation associated markers in irritable bowel disease - an explorative randomized, double blinded, controlled pilot trial. |journal=Neuro Endocrinology Letters |date=March 2021 |volume=42 |issue=1 |pages=1–12 |pmid=33930939}}</ref> There are no approved medical uses for zeolites as of 2024. Regardless, they are widely marketed as [[dietary supplements]].