Table of Contents
Zeolite is a group of silicate minerals that a family of hydrated aluminosilicate minerals that contain alkali and alkaline-earth metals with unusual properties with importance industrial application. Zeolite form is usually well-formed crystals with pale colors and generally soft and can easily crushed.They are found in geologically young volcanic fields. Most common zeolite minerals are analcime, chabazite, clinoptilite, mordenite, natrolite, heulandite, phillipsite and stilbite.
The zeolites form a large family of hydrous silicates which show close similarities in composition and in their associations and mode of occurrence. They are silicates of aluminum with sodium and calcium as the important bases. They average from 3J to 5 5 in hardness and from 2.0 to 2.4 in specific gravity. Many of them fuse readily with marked intumescence, hence the name zeolite, from two Greek words meaning to boil and stone. They are secondary minerals found characteristically in cavities and veins in basic igneous rocks.
Name: The term zeolite was first written in 1756 by the Swedish mineralogist Axel Fredrik Cronstedt. He named the zeolite material from the Greek z (zéō) meaning “stone” to “zeolite”.
Chemical Properties
| Chemical Classification | Silicate |
| Formula | (Ca,K2,Na2)2[Al2Si4O12]2·12H2O |
Zeolite Physical Properties
| Color | Colorless, white, yellow, pink, red |
| Streak | White |
| Luster | Vitreous |
| Mohs Hardness | 4-5 |
| Fracture | irregular/uneven |
Zeolite Occurrence
Natural zeolites occur where volcanic rocks and ash layers react with alkaline groundwater. Zeolites also crystallize in shallow marine basins in post-sedimentation environments for periods ranging from thousands to million years. Naturally occurring zeolites are rarely pure and are contaminated to varying degrees by other minerals, metals, quartz or other zeolites. Therefore, naturally occurring zeolites are excluded from many important commercial applications where uniformity and purity are required.
Zeolites are converted to other minerals under weathering, hydrothermal change or metamorphic conditions.
Production of Zeolite
Industrially important zeolites are produced synthetically. Typical procedures require that aqueous alumina and silica solutions be heated with sodium hydroxide. Equivalent reagents include sodium aluminate and sodium silicate. Other variations include changes in cations, including quaternary ammonium cations.
Synthetic zeolites have some important advantages over their natural analogs. Synthetic materials are produced in uniform, pure phase states. It is also possible to produce zeolite structures that are not visible in nature. Zeolite A is a well-known example. Since the main raw materials used in the production of zeolites are silica and alumina, which are the most abundant mineral components in the world, their potential to provide zeolites is almost limitless.
Natural occurrence
As of 2016, the world’s annual natural zeolite production is around 3 million tons. China among the major manufacturers in 2010 (2 million tons), South Korea (210,000 tons), Japan (150,000 tons), Jordan (140,000 tons), Turkey (100,000 tons), Slovakia (85,000 tonnes) and the US (59,000 tons) took place. The low availability of zeolite-rich rocks and the scarcity of competing minerals and rocks are probably the most important factors for large-scale use. According to the United States Geological Survey, a significant percentage of the material sold as zeolite in some countries is likely to be milled or cut volcanic tuff containing only a small amount of zeolite. Some examples of this use include dimension stone (such as modified volcanic tuff), lightweight aggregate, pozzolanic cement and soil conditioners.
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”. Currently there are a number of theories attempting to explain the reasoning behind this question.
Uses Area
- Zeolites are widely used as ion exchange beds in domestic and commercial water purification, softening and other applications. In chemistry, zeolites are used to separate molecules (only molecules of certain sizes and shapes can pass) and can be analyzed as traps for molecules.
- Zeolites are also commonly used as catalysts and sorbents. Well defined pore structures and adjustable acidity enable them to be active in a wide range of reactions.
- Zeolites have the potential to provide separation of specific and specific gases, including the removal of H2O, CO2 and SO2 from low-grade natural gas streams. Other distinctions include noble gases, N 2, O 2, freon and formaldehyde.
- Zeolites help silver in naturally emitted light, which can lead to new lighting technologies that complement or replace fluorescent lamps or LEDs.
- Built-in oxygen generating systems (OBOGS) and Oxygen concentrators use zeolites in combination with pressure oscillating adsorption to remove pressurized nitrogen from compressed air to provide oxygen for the high-altitude air crew, as well as household and portable oxygen sources.
- Synthetic zeolites, like other porous materials (eg, MCM-41), are widely used as catalysts in the petrochemical industry, for example in liquid catalytic cracking and hydro cracking.
- Catalytic cracking uses the reactor and a regenerator. The feed is injected into the hot, fluidized catalyst where large gas molecules are broken down into smaller gasoline molecules and olefins.
- In advanced nuclear waste reprocessing methods, zeolites allow some to release ions, while their microporous capabilities ensure effective removal and permanently shutdown of many fission products from waste.
- Zeolites can be used as solar thermal collectors and for adsorption cooling. In these applications, hydration and dewatering capabilities are utilized while maintaining high adsorption temperature and structural stability.
- The lump-free cat litter is usually made of zeolite or diatomite.
- Synthetic zeolites are used as additives in the production process of warm mix asphalt concrete.
- When added to Portland cement as a pozzolan, they can reduce chloride permeability and improve workability. They help reduce the weight and provide slower drying and help with moderate water content, which increases fracture strength.
- Thomsonites, one of the rare zeolite minerals, were collected as precious stones from a series of lava flows along Lake Superior in Minnesota.
- The color combinations of these thosonite nodules have concentric rings: black, white, orange, pink, purple, red and many green tones. Some nodules have copper inclusions and are rarely found with copper “eyes”.
- Research and development of many biochemical and biomedical applications of zeolites, particularly naturally occurring species, such as heulandite, clinoptilolite and chabazite, are ongoing.
- Zeolite based oxygen concentrator systems are widely used to produce medical grade oxygen. The zeolite is used as a molecular sieve to form purified air from oxygen using the ability to trap impurities in a process that releases highly purified oxygen and up to 5% argon containing nitrogen adsorption.
- The QuikClot brand hemostatic agent used to stop heavy bleeding includes the calcium-loaded zeolite form in the kaolin clay.
- In agriculture, clinoptilolite (a naturally occurring zeolite) is used as soil treatment. Provides a slowly released source of potassium. If previously ammonium charged, the zeolite may serve a similar function in slow release of nitrogen. Zeolites can also act as water moderators, which will absorb 55% of their weight in water and slowly release it at the request of the plant. This feature can prevent root rot and moderate drought cycles.
- Pet stores market zeolites for use as filter additives in aquariums, where they can be used to adsorb ammonia and other nitrogenous compounds.
Zeolite Group Minerals and Formulas
| Alflarsenite | NaCa2Be3Si4O13(OH) · 2H2O |
| Amicite | K2Na2Al4Si4O16 · 5H2O |
| Ammonioleucite | (NH4,K)(AlSi2O6) |
| Analcime | Na(AlSi2O6) · H2O |
| Bellbergite | (K,Ba,Sr)2Sr2Ca2(Ca,Na)4[Al3Si3O12]6 · 30H2O |
| Bikitaite | LiAlSi2O6 · H2O |
| Boggsite | Ca8Na3(Si,Al)96O192 · 70H2O |
| Brewsterite-Ba | (Ba,Sr)[Al2Si6O16] · 5H2O |
| Brewsterite-Sr | (Sr,Ba,Ca)[Al2Si6O16] · 5H2O |
| Chabazite-Levyne Subgroup | |
| Chabazite-Ca | (Ca,K2,Na2)2[Al2Si4O12]2 · 12H2O |
| Chabazite-K | (K2,Ca,Na2,Sr,Mg)2[Al2Si4O12]2 · 12H2O |
| Chabazite-Mg | (Mg0.7K0.5Ca0.5Na0.1)[Al3Si9O24]·10H2O |
| Chabazite-Na | (Na2,K2,Ca,Sr,Mg)2[Al2Si4O12]2 · 12H2O |
| Chabazite-Sr | Sr2[Al2Si4O12]2 · 12H2O |
| Lévyne-Ca | (Ca,Na2,K2)[Al2Si4O12] · 6H2O |
| Lévyne-Na | (Na2,Ca,K2)[Al2Si4O12] · 6H2O |
| Chiavennite | CaMnBe2Si5O13(OH)2 · 2H2O |
| Clinoptilolite | Na,Ca,K |
| Clinoptilolite-Na | Na6(Si30Al6)O72·20H2O |
| Cowlesite | CaAl2Si3O10 · 6H2O |
| Dachiardite-Ca | (Ca,Na2,K2)5Al10Si38O96 · 25H2O |
| Dachiardite-K | K4(Si20Al4O48)·13H2O |
| Dachiardite-Na | (Na2,Ca,K2)5Al10Si38O96 · 25H2O |
| Direnzoite | NaK6MgCa2(Al13Si47O120) · 36H2O |
| Edingtonite | Ba[Al2Si3O10] · 4H2O |
| Epistilbite | CaAl2Si6O16 · 5H2O |
| Erionite | |
| Erionite-Ca | (Ca,K2,Na2)2[Al4Si14O36] · 15H2O |
| Erionite-K | (K2,Ca,Na2)2[Al4Si14O36] · 15H2O |
| Erionite-Na | (Na2,K2,Ca)2[Al4Si14O36] · 15H2O |
| Faujasite | |
| Faujasite-Ca | (Ca,Na2,Mg)3.5[Al7Si17O48] · 32H2O |
| Ferrierite | |
| Ferrierite-K | (K2,Na2,Mg,Ca)3-5Mg[Al5-7Si27.5-31O72] · 18H2O |
| Ferrierite-Mg | (Mg,Na2,K2,Ca)3-5Mg[Al5-7Si27.5-31O72] · 18H2O |
| Ferrierite-Na | (Na2,K2,Mg,Ca)3-5Mg[Al5-7Si27.5-31O72] · 18H2O |
| Ferrochiavennite | Ca1-2Fe[(Si,Al,Be)5Be2O13(OH)2] · 2H2O |
| Flörkeite | (K3Ca2Na)[Al8Si8O32] · 12H2O |
| Garronite-Ca | Na2Ca5Al12Si20O64 · 27H2O |
| Gaultite | Na4Zn2Si7O18 · 5H2O |
| Gismondine-Ba | Ba2Al4Si4O16 · 4-6H2O |
| Gismondine-Ca | CaAl2Si2O8 · 4H2O |
| Gmelinite | |
| Gobbinsite | Na5(Si11Al5)O32 · 11H2O |
| Goosecreekite | Ca[Al2Si6O16] · 5H2O |
| Gottardiite | Na3Mg3Ca5Al19Si117O272 · 93H2O |
| Harmotome | (Ba0.5,Ca0.5,K,Na)5[Al5Si11O32] · 12H2O |
| Heulandite subgroup | |
| Heulandite-Ba | (Ba,Ca,K)5(Si27Al9)O72 · 22H2O |
| Heulandite-Ca | (Ca,Na)5(Si27Al9)O72 · 26H2O |
| Heulandite-K | (K,Ca,Na)5(Si27Al9)O72 · 26H2O |
| Heulandite-Na | (Na,Ca,K)6(Si,Al)36O72 · 22H2O |
| Heulandite-Sr | (Sr,Na,Ca)5(Si27Al9)O72 · 24H2O |
| Hsianghualite | Ca3Li2(Be3Si3O12)F2 |
| Kirchhoffite | Cs(BSi2O6) |
| Laumontite | CaAl2Si4O12 · 4H2O |
| Lovdarite | K2Na6Be4Si14O36 · 9H2O |
| Maricopaite | Pb7Ca2(Si,Al)48O100 · 32H2O |
| Martinandresite | Ba2(Al4Si12O32)·10H2O |
| Mazzite-Mg | (Mg,K,Ca)5(Si26Al10)O72 · 28H2O |
| Mazzite-Na | Na8[Al4Si14O36]2 · 30H2O |
| Merlinoite | (K,Na)5(Ca,Ba)2Al9Si23O64 · 23H2O |
| Montesommaite | (K,Na)9Al9Si23O64 · 10H2O |
| Mordenite | (Na2,Ca,K2)4(Al8Si40)O96 · 28H2O |
| Mutinaite | Na3Ca4Si85Al11O192 · 60H2O |
| Nabesite | Na2BeSi4O10 · 4H2O |
| Natrolite Subgroup | |
| Gonnardite | (Na,Ca)2(Si,Al)5O10 · 3H2O |
| Mesolite | Na2Ca2Si9Al6O30 · 8H2O |
| Natrolite | Na2Al2Si3O10 · 2H2O |
| Paranatrolite | Na2Al2Si3O10 · 3H2O |
| Scolecite | CaAl2Si3O10 · 3H2O |
| Offretite | KCaMg(Si13Al5)O36 · 15H2O |
| Pahasapaite | Li8(Ca,Li,K)10.5Be24(PO4)24 · 38H2O |
| Parthéite | Ca2(Si4Al4) O15 (OH)2•4H2O |
| Paulingite-Ca | (Ca,K,Na,Ba,◻)10 (Si, Al)42O84•34H2O |
| Paulingite-K | (K2,Ca,Na2,Ba)5[Al10Si35O90] · 45H2O |
| Paulingite-Na | (Na2,K2,Ca,Ba)5[Al10Si35O90] · 45H2O |
| Perlialite | K9Na(Ca,Sr)[Al2Si4O12]6 · 15H2O |
| Phillipsite | |
| Pollucite | (Cs,Na)2(Al2Si4O12) · 2H2O |
| Roggianite | Ca2Be(OH)2Al2Si4O13 · 2.5H2O |
| Stilbite subgroup | |
| Barrerite | (Na,K,Ca0.5)2[Al2Si7O18] · 7H2O |
| Stellerite | Ca4(Si28Al8)O72 · 28H2O |
| Stilbite-Ca | NaCa4[Al9Si27O72] · nH2O |
| Stilbite-Na | (Na,Ca,K)6-7[Al8Si28O72] · nH2O |
| Terranovaite | (Na,Ca)8(Si68Al12)O160 · 29H2O |
| Thomsonite-Ca | NaCa2[Al5Si5O20] · 6H2O |
| Thomsonite-Sr | Na(Sr,Ca)2[Al5Si5O20] · 7H2O |
| Tschernichite | (Ca,Na2)[Al2Si4O12] · 4-8H2O |
| Tschörtnerite | Ca4(Ca,Sr,K,Ba)3Cu3[Al3Si3O12]4(OH)8 · nH2O |
| Wairakite | Ca(Al2Si4O12) · 2H2O |
| Weinebeneite | CaBe3(PO4)2(OH)2 · 4H2O |
| Wenkite | (Ba,K)4(Ca,Na)6[(Si,Al)20O39(OH)2](SO4)3 · 0.5H2O |
| Willhendersonite | KCa[Al3Si3O12] · 5H2O |
| Yugawaralite | CaAl2Si6O16 · 4H2O |
References
- Dana, J. D. (1864). Manual of Mineralogy… Wiley.
- Mindat.org. (2019): Mineral information, data and localities.. [online] Available at: https://www.mindat.org/ [Accessed. 2019].
- Wikipedia contributors. (2019, June 25). Zeolite. In Wikipedia, The Free Encyclopedia. Retrieved 02:10, June 27, 2019, from https://en.wikipedia.org/w/index.php?title=Zeolite&oldid=903388071
