Clinoptilolite September 9th, 2009
Clinoptilolite is a naturally-occurring zeolite, formed by the devitrification (ie the conversion of glassy material to crystalline material) of volcanic ash in lake and marine waters millions of years ago. It is the most researched of all zeolites and is widely regarded as the most useful. In common with other zeolites, clinoptilolite has a cage-like structure consisting of SiO4 and AlO4 tetrahedra joined by shared oxygen atoms. The negative charges of the AlO4 units are balanced by the presence of exchangeable cations – notably calcium, magnesium, sodium, potassium and iron. These ions can be readily displaced by other substances, for example heavy metals (mercury, lead, cadmium, etc..) and ammonium ions. This phenomenon is known as cationic exchange, and it is the very high cationic exchange capacity of clinoptilolite which provides many of its useful properties.
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Zeolite in Soil Amendments September 8th, 2009
Natural Zeolites
Natural zeolites were formed by the chemical reaction of volcanic ash and alkaline salt water. This chemical reaction gives natural zeolites an open three-dimensional honeycomb and porous structure. The mined zeolite ore is dried, crushed, and screened to meet USGA particle size specifications. Different natural zeolite deposits can have quite different chemical and physical characteristics. A high quality natural zeolite has a high CEC, low clay, low sodium, and high potassium.
Atlas of Zeolite Framework Types September 8th, 2009
Ch. Baerlocher, W.M. Meier, D.H. Olson
Structure Commission of the International Zeolite Association
The ATLAS contains an entry for each unique zeolite framework type. The term zeolite framework refers to a corner-sharing network of tetrahedrally coordinated atoms. In compliance with the changes in zeolite nomenclature recommended by IUPAC in 2001(2) the title of the Atlas had to be changed from ‘Atlas of Zeolite Structure Types’ to ‘Atlas of Zeolite Framework Types’. This is because the term ’structure’ implies both the framework and the extra-framework constituents of a zeolite and the latter are excluded in the framework description.
Zeolites, Natural and Synthetic September 8th, 2009
Two Kinds of Zeolites: Natural and Synthetic
Synthetic and natural zeolites are hydrated aluminosilicates with symmetrically stacked alumina and silica tetrahedra which result in an open and stable three-dimensional honeycomb structure with a negative charge. The negative charge within the pores is neutralized by positively charged ions (cations) such as sodium. Over 150 zeolite structural types have been identified.
What are Zeolites? September 8th, 2009
Zeolites are microporous crystalline solids with well-defined structures. Generally they contain silicon, aluminum and oxygen in their framework and cations, water and/or other molecules within their pores. Many occur naturally as minerals, and are extensively mined in many parts of the world. Others are synthetic, and are made commercially for specific uses, or produced by research scientists trying to understand more about their chemistry.
The Zeolite Mineral, Properties and Uses September 8th, 2009
Zeolites have many useful purposes. They can perform ion exchange, filtering, odor removal, chemical sieve and gas absorption tasks. The most well known use for zeolites is in water softeners. Calcium in water can cause it to be “hard” and capable of forming scum and other problems. Zeolites charged with the much less damaging sodium ions can allow the hard water to pass through its structure and exchange the calcium for the sodium ions. This process is reversible.
In a similar way zeolites can absorb ions and molecules and thus act as a filter for odor control, toxin removal and as a chemical sieve. Zeolites can have the water in their structures driven off by heat with the basic structure left intact. Then other solutions can be pushed through the structure. The zeolites can then act as a delivery system for the new fluid. This process has applications in medicine, livestock feeds and other types of research.
Zeolites added to livestock feed have been shown to absorb toxins that are damaging and even fatal to the growth of the animals, while the basic structure of the zeolite is biologically neutral. Aquarium hobbyists are seeing more zeolite products in pet stores as zeolites make excellent removers of ammonia and other toxins. Most municipal water supplies are processed through zeolites before public consumption. These uses of zeolites are extremely important for industry, although synthetic zeolites are now doing the bulk of the work.
Zeolite Mineral History & Properties September 2nd, 2009
Historically, mineral zeolite was discovered in 1756 by a Swedish mineralogist named Freiherr Axel Fredrick Cronstedt, who derived the name from the Greek words zein and lithos meaning “boiling stones”. Over the next 200 years chemists and mineralogists studied zeolites and discovered the dehydration, adsorption, and cation exchange properties of this mineral.
Database of Zeolite Structures August 13th, 2009
The database of the Structure Commission of the International Zeolite Association provides structural information on all zeolite structure types. This includes crystallographic data and drawings for all zeolite framework types, simulated powder patterns for representative materials and relevant references.
-Descriptions and drawings of each framework type
-User-controlled animated displays of each framework type
-Crystallographic data and simulated powder diffraction patterns for representative materials
-Relevant references
-Detailed instructions for building models
-Descriptions of some families of disordered zeolite structures
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Zeolites August 13th, 2009
Natural zeolites form where volcanic rocks and ash layers react with alkaline groundwater. Zeolites also crystallized in post-depositional environments over periods ranging from thousands to millions of years in shallow marine basins. Naturally occurring zeolites are rarely pure and are contaminated to varying degrees by other minerals, metals, quartz or other zeolites. For this reason, naturally occurring zeolites are excluded from many important commercial applications where uniformity and purity are essential.
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.