|Title||Over de systematische veranderingen in uitwisselings-capaciteit van klei|
|Source||University. Promotor(en): J. Hudig. - Wageningen : Veenman - 148|
|Publication type||Dissertation, internally prepared|
|Keyword(s)||kleimineralen - clay minerals|
|Abstract||Clay particles in suspension are surrounded by an electrical double layer, whose inner layer consists of OH -. There is a linear relation between the amount of OH -in this inner coat and the pH of the equilibrium solution. Consequently the charge on clay particles is a function of the pH of the equilibrium solution.
The degree of flocculation depends mainly on the electrokinetic potential of the clay particles. Therefore differences in flocculation with several salts are closely related to valency and polarizability of the ions.
Calculations from measurements of the capacity of the electrical double layer suggested a specific surface area of 500 m 2per g of bentonite.
Cation exchange does not occur only on clay minerals containing AI in tetravalent positions as it was earlier suggested. Ground kaolinite and halloysite, neither of which contains tetravalent AI, have a considerable cation-exchange capacity. Anion exchange rarely occurs on clays. This follows from the fact that after breaking such a layer as Al 2 (OH) 6 of a clay mineral, there are usually no Al ions in the equilibrium solution to form a double layer with Al as inner coat.