Activity of Clays and Zeolites
Understanding the activity of zeolites helps to understand their powerful detoxifying capabilities.
Both clays and zeolites are hydrated alumino-silicates and have similar mineral make ups in their analysis (i.e. silicon and aluminium oxide are in the highest proportion, and they all contain the “clay minerals” potassium oxide, calcium oxide, iron oxide, magnesium oxide).
The following is a brief mineralogical description of silicates (no Cation Exchange capabilities) and alumino-silicates (have Cation Exchange capabilities).
Silicates (Quartz Crystals)
Oxygen and silicon are both found in abundant quantities in the earth’s crust, oxygen reacts strongly with elements such as silicon that can give up electrons, therefore a large number of naturally occurring minerals are silicates. The primary building unit of a silicate consists of four oxygen atoms around a silicon atom, the oxygens being attracted to the silicon by electrostatic forces resulting from the exchange of electrons. Silicates have a three dimensional molecular structure.
Alumino-Silicates (Clays and Zeolites
Aluminium, like silicon and oxygen, is also quite abundant in the earth’s crust, and often substitutes for the silicon atom in the primary building unit, thus forming alumino-silicates in place of silicates. This substitution can occur because aluminium is similar in size to silicon, and will occur to the extent determined by the relative availability of aluminium and silicon in the solution from which the material crystallises.
Replacement of some of the silicon by aluminium is significant because the charge imbalance so introduced is compensated for by cations attracted to, but not actually part of, the crystal structure. These cations can be exchanged with others in adjacent solutions, the degree of exchange depending on material types and concentrations, and this gives alumino-silicates many interesting properties, such as detoxifying and anti-oxidant capabilities. Uneven distribution of surface charge in alumino-silicates also results in the attraction of polar molecules (water), and this characteristic results in adsorption of numerous molecules onto the solid surface.
Structure of Alumino-Silicates
Alumino-silicates can have either two or three dimensions. Clays have a two dimensional “sheet” structure. Zeolites have a three dimensional “rigid” framework. The third dimension allows more surface area for cation exchange to take place, therefore there is increased chemical reaction. Quartz also has a three dimensional “rigid” framework but does not have the capacity for Cation Exchange as there are no aluminium atoms present.
Cation Exchange Capacity (CEC)
The CEC of a mineral shows its capacity for chemical reaction to take place. The chemical reaction takes place on the outer surface of the mineral molecule. During the chemical reaction there is an exchange of positive and negative ions.
The benefit of the CEC exchange in health and skin care is that toxic positive ions are drawn from the skin, and the layer just underneath the skin, by the negative ions of the mineral. The toxic positive ions then cling to the negative ion of the mineral molecule (adsorption). The toxic matter is removed with the mask. Cation Exchange only takes place in a moist environment.
Zeolites, being three dimensional and porous, exhibit much greater surface area per unit volume than clays and therefore have higher cation exchange and polar molecule adsorption capacities than clays.
The following link is to a condensed version of a report prepared by Peter Cooksey, B.E., an Australian mineralogist and wastewater consultant to the zeolite industry. If you would like the full version please contact us.