HackingTheUniverse

Zeolites are microporous structures made of aluminosilicate minerals that tend to absorb water like a sponge. Because of their ability to attach positive ions and sort substances by molecular size, they are often referred to as molecular sieves.

Database details 2.7 million possible structures for molecular sieves - [nanowerk.com]

Zeolites can be viewed as “a membrane that will only let molecules of a certain size pass through,” Deem said. “But they also do other things. They have an affinity for some molecules, so they’re used to absorb odors, for instance, in flower shops.”

In laundry detergents, zeolites trade soft ions for hard ones in the water, and the petrochemical industry uses zeolites to crack petroleum into gasoline, diesel and other products. After the accident at the Three Mile Island nuclear power plant, zeolites were used to adsorb radioactive ions.

Zeolites are a fine lattice, a molecular sieve that can let molecules of a certain size pass while blocking others. They can also adsorb molecules, attracting and gripping certain substances — for which cats and their owners are grateful.

Natural zeolites are often the product of volcanic activity, as rocks, ash and alkaline water combine and crystallize over thousands of years. “The term zeolite comes from the combination of two Greek words that mean ‘boiling’ and ’stone,’” Deem said.

The Zeolite Group of Minerals - [galleries.com]

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 reversable. 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.

What are Zeolites ? - [bza.org]

Zeolites have the ability to act as catalysts for chemical reactions which take place within the internal cavities. An important class of reactions is that catalysed by hydrogen-exchanged zeolites, whose framework-bound protons give rise to very high acidity. This is exploited in many organic reactions, including crude oil cracking, isomerisation and fuel synthesis. Zeolites can also serve as oxidation or reduction catalysts, often after metals have been introduced into the framework. Examples are the use of titanium ZSM-5 in the production of caprolactam, and copper zeolites in NOx decomposition.

Underpinning all these types of reaction is the unique microporous nature of zeolites, where the shape and size of a particular pore system exerts a steric influence on the reaction, controlling the access of reactants and products. Thus zeolites are often said to act as shape-selective catalysts. Increasingly, attention has focused on fine-tuning the properties of zeolite catalysts in order to carry out very specific syntheses of high-value chemicals e.g. pharmaceuticals and cosmetics.

Nanotechnology assembly with living materials - [nanowerk.com]

Zeolites L are crystalline aluminosilicates, a biocompatible material – basically a little piece of transparent volcanic rock – and the German research team is currently trying to use these nanocontainers (Zeolite L contains one-dimensional channels running through the whole crystal; a single crystal with a diameter of 550 nm consists of about 80,000 parallel channels) for in vivo applications. “I can foresee several applications in nanomedicine but also in other material fields” says De Cola.

…and…

This research opens the possibility of arranging living cells and nanomaterials in various combinations and have them self-assemble into complex structures. De Cola even believes that an exchange of specific information between the zeolite and/or the bacteria is possible. For instance, substances stored inside the Zeolite’s nanochannels could be transferred to the living cells; vice versa, substances discharged from the bacteria could be captured by the crystals and analyzed.