Abstract: It has been demonstrated that ferric iron is the principal source of the oxidizing action of the surface of attapulgite clay. The extent of oxidizing action in a given time (the oxidizing power) has been determined as a function of the temperature of calcination of the clay in the range 100–900°C.
The oxidizing power was measured with TiCl3 a in aqueous acid medium by direct titration of the clay in situ and by titration of extracts of the clay. The dissolution of the metallic cations of the clay was also studied in the same medium. The results have been correlated with structural changes caused by the calcination of attapulgite.