Zeolite Structure
What Type of Zeolite Do We Use?
The zeolite used in our products is composed of approximately 85% clinoptilolite [cli-nop-til-o-lite] and 15% mordenite [mor-den-ite] with small traces of other minerals <chemical analysis>. It is a hydrated alkali alumino silicate that is one of the most abundant forms in the zeolite family. The precise composition of clinoptilolite is, subject to a degree of variation being a naturally occurring mineral. However, the approximate empirical formula is (Ca, Fe, K, Mg, Na)3-6Si30Al6O72.24H2O. The Chemical Abstracts Service (CAS) Number for clinoptilolite is 12173-10-3.
The formula and the resultant structure are extremely important. Notice that clinoptilolite is primarily composed of oxygen [O72], silicon [Si30], water [24H2O] and aluminium [Al6] (in that order). The other minerals in far lesser quantities are iron, sodium, calcium, potassium and magnesium. <chemical analysis>
What makes zeolite so unique is its rigid structure which is arranged in an ordered, matrix configuration resembling a bee’s honeycomb. The microscopic chambers, channels, cavities, pores, cells, or cages (we call them cages as they trap molecules), which form this intricate honeycomb structure, are usually uniform in shape.
As the zeolites are microporous [a material containing pores with diameters less than 2 nanometres] crystalline solids they have a well-defined geometric framework (honeycombs) such as the two shown below.
A defining feature of all zeolites is that they are insoluble and are composed of an extremely stable combination of silicon, oxygen and aluminium in their frameworks. Most zeolites are made up of 4-connected networks of atoms, called a tetrahedron. A tetrahedron is formed with a silicon atom in the middle and oxygen atoms at the corners. This inbuilt stable framework is why no free aluminium exists in the zeolite which we process for use in our products even though the aluminium comprises 12% of the zeolite.
These tetrahedra can then be link together by their corners (see illustration below) to form a variety of beautiful structures. The framework structure may contain the linked cages, which are of the right size to allow smaller molecules to enter - i.e. the limiting cage sizes are roughly between 3 and 10 angstroms in diameter.
This is due to a very regular structure of the cage’s molecular dimensions. The maximum size of the molecular or cation that can enter the cages of a zeolite is determined by the diameters of the cages. These are conventionally defined by the ring size of the aperture, where, for example, the term ‘8 ring’ refers to a closed loop that is built from 8 tetrahedron coordinated silicon (or aluminium) atoms and 8 oxygen atoms.
The molecular structure of clinoptilolite is shown below. This model is courtesy of the Mineralogy Database, a quite remarkable web site containing over 4,700 individual mineral species descriptions, images, physical and optical properties, crystallography and formulas with appropriate links and a comprehensive image library. The website, www.webmineral.comalso features thousands of display case mineral samples for sale and is the creation of one man, Mr. David Barthelmy.
To get a better idea of the molecular structure of clinoptilolite click the button below. On the image that will appear adjust the side blue bar so the image is centered in the window. There are two bars in the image on the left hand side. The vertical index bottom left, gives the colour codes for the various elements that make up the molecule. The horizontal menu bar at the top left controls the various views of the molecule, its magnification and rotation.
To rotate the molecule, click on the second small button which looks like a black triangle pointing to the right. To stop the rotation click on the third button with a black square on it. To magnify (zoom) the image, click on the fourth button with the plus (+) sign. The more clicks, the greater the magnification. Conversely, to lessen the magnification, click the button with the negative (-) sign. The first button with the cross (X) resets the magnification back to normal.
The button at the end with the circle (O) controls the various views of the molecule. The different views are:-
Opening image shows all the molecules in their respective positions within the molecule. The rose coloured triangles are the tetrahedra that lie within the molecule. Notice that each tetrahedron has an oxygen atom at each of the four triangle points. The potassium and the magnesium atoms (the green atoms) are on the outside of the molecule.
The second image shows just the chemical bonds that join the atoms together.
The third image shows the first image but without the outline of the rose triangle tetrahedra. Try the magnification, it’s quite remarkable.
The fourth image shows how compacted the molecule actually is. Unfortunately this image leaves very little space between the atoms to see the internal construction and relationship of the atoms, hence the addition of the first and third images.
The fifth image displays just the outline of the tetrahedra without the molecules and the pattern they form. Observe the symmetrical arrangement comprising four groups made up of six tetrahedra each. Each group joins the adjacent group at only one apex of one tetrahedron. If the image were to be tipped up so we were looking through it, it would resemble the blue pattern shown above in the text on the page.
If the button is clicked again the sequence on images is repeated again. However if you place the cursor over the molecule you can control the rotation whichever way you would like to view it. Click through the images until you get to the fifth image or the one with the rose tetrahedra. You can see now how they form the structure of the cages.
These rings are not always perfectly flat and symmetrical due to a variety of effects, including pressures during formation and the strain induced by the bonding between units that are needed to produce the overall structure, or coordination of some of the oxygen atoms of the rings to cations within the structure. Therefore, the cage openings are not always identical in natural zeolites and that gives them their great versatility in dealing with many different molecules. And for this reason, naturally occurring zeolites are often excluded from many important commercial applications where uniformity is essential.
Zeolites are also called ‘molecular sieves’. The term refers to the mineral’s unique ability to selectively sort and absorb molecules based primarily on size. In synthetic zeolites the cages are all exactly the same size and are therefore very good for extracting one or two particular molecules (cations). Natural zeolites have the advantage over synthetic zeolites of having superior crystalline structures with ‘pores’ or ‘cages’ of differing dimensions suitable for many varied purposes. The structure purity of the cages remains unpolluted over time.
Molecular sieves are natural chelators, having the ability to be used as tools for cation exchange. The term chelation [key-lay-shun] means a substance (usually negatively charged) that can attract (electro-chemically bond with) toxic minerals, metals and other materials within the body’s fluids allowing the body to dispose of them naturally.
Having read all of the above, the reader would no doubt be wondering how is it possible that some zeolite products can be advertised as 'liquid' zeolite. Well of course, anyone can advertise their product the way they want even if it was not correct. However, if the product really was a liquid, then there would be no cage structure. It is essential to have the cage structure otherwise the zeolite has no way of not only, attracting the positive charged cations (the negative charge derives from the chemical combination of the structure so if you smash the structure there would be no negative charge) but trapping the cations and holding them there within the structure, unable to be re-absorbed before the zeolite passes out of the body.
Scientifically, the statement is a complete misnomer and/or contradiction by definition. If the zeolite is a liquid it would not be zeolite and if it is zeolite then it can’t be a liquid. What we believe all these type of products consist of, is an amount of micronised or sub-micronised zeolite particles held in suspension within a liquid. But one cannot have liquid zeolite. Usually, the more a supplier wants to call their product a liquid the smaller the amount of actual zeolite will be found in the product.
Of course the smaller the amount of zeolite in a product the less effective it will be.
A typical clinoptilolite impression structure showing the different sized cages that make up the structure of the zeolite used in our products.
Because of its unique structure, the cages in the porous structure attract and hold a wide variety of cations, such as Na+, K+, Ca2+, Mg2+ and many others. These positive ions are rather loosely held and can readily be exchanged for others in solution. <cations>