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Zeolite the nano scale Swiss Cheese

Now I have told you about two different types of caesium absorber, I think I will continue with the C plan and carry on writing about the C word. The C word is cesium.

Now while you can eat Prussian blue and drink water filtered through clay laden soils, you might want to ask how does cesium get removed from waste water. One method for caesium removal is to use a zeolite as an ion exchanger.

In common with the clay the zeolite has a vast number of cations which can be exchanged, in the zeolite I will show you it normally has lots of sodium cations but it is possible to exchange the sodium cations for cesium.

It is also important to see how the zeolite is a mini version of a Swiss cheese, it is a solid which is full of holes. Before any of you who might be buying zeolite start to object at being solid a product which is full of holes please bear in mind that the holes in the zeolite are the things which make it do useful things for us.

Here is a picture of the framework of aluminium, silicon and oxygen atoms. This framework has a negative charge; I have left out the cations which balance the charge for reasons of clarity. Please look to see the voids and holes in the solid.

The cages in a zeolite

A second view has been done with a space filling version of the framework, note that it is not so space filling that the holes get plugged. It is still possible to look through the holes to the other side.

A space filling view of the zeolite

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