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A zeolite is a crystalline hydrated aluminosilicate with a framework structure that encloses cavities (or pores) inhabited by cations and water molecules, both of which have a lot of freedom of movement, and this is responsible for ion exchange and reversible dehydration. This classification places it in the “molecular sieves” category of materials.
Zeolites are a class of silicate minerals having unique properties that are used in industry. They normally create attractive well-formed pale-colored crystals, are rather soft, and can be crushed and pulverised. They are found in volcanic fields that are geologically young. Analcime, chabazite, clinoptilite, mordenite, natrolite, heulandite, phillipsite, and stilbite are the most prevalent zeolite minerals.
Natural zeolites:
The chemical reaction between volcanic glass and saltwater water produces zeolites in nature. Temperatures favourable to the natural reaction range from 27oC to 55oC, with a pH of 9 to 10. The reaction takes 50 to 50,000 years to complete in nature.
Other minerals [e.g Fe2+, SO4-, quartz, other zeolites, and amorphous glass] contaminate naturally occurring zeolites to variable degrees. Many key commercial applications that require uniformity and purity do not employ naturally occurring zeolites.
Chemical properties
Zeolites are three-dimensional, micro-porous, crystalline minerals with exceptionally well-structured structures that include aluminium, silicon, and oxygen in a regular framework, as well as cations and water in the pores.
Silicon and aluminium atoms are tetrahedrally coupled thanks to shared oxygen atoms. To be exact, both are alumino-silicates. On the other hand, their crystalline structure is distinct.
When water is absorbed and removed between the layers, many types of clay have a layered crystalline structure (similar to a deck of cards) that shrinks and swells. Zeolites have a honeycomb-like solid three-dimensional crystalline structure with a network of interconnected tunnels and cages.
Sedimentary rocks:
Because they crystallise from a liquid, igneous rocks are frequently referred to as basic rocks. Sedimentary rocks are derived rocks in this situation because they are made up of fragments of pre-existing rocks.
Zeolites can be found in many different sedimentary strata. They develop from a variety of elements, including volcanic glass, feldspar, feldspathoids, smectite, and kaolinite, and are post-depositional minerals.
Conclusion:
Natural zeolites have a number of benefits, including being abundant, affordable, and environmentally beneficial. In a variety of environmental and industrial applications, zeolites have proven to be useful. The adsorption properties of zeolites are used in these applications. Zeolites have been used to remove pollutants from both gas and wastewater, as well as to improve the durability of concrete materials and as a catalyst for energy production.
Natural zeolites have physicochemical features that allow them to adsorb or ion exchange certain compounds, allowing them to remove pollutants from water. Aside from pollution elimination, natural zeolites have been discovered to have a high-performance capacity in improving the stability of the final cement or concrete with the right dosage of natural zeolite in the application of constructions.
