The evolution of textural properties of Na/Ca-bentonite following hydrothermal treatment at 80 and 300°C in the presence of Fe and/ or Fe oxides

The evolution of textural properties of Na/Ca-bentonite from Wyoming (MX-80) was studied by adsorption of nitrogen, water vapour, and ethylene glycol monoethyl ether. Clay suspensions were heated at 80 and 300°C for up to 9 months in the absence of or in the presence of Fe and/or Fe oxides. The treatment without Fe did not change the textural properties of the samples significantly. The treatment at 80°C in the presence of Fe resulted in a considerable increase in the external surfaces areas of the samples. The total and external surface areas and swelling capacities of the samples decreased following the treatment at 300°C in the presence of Fe and Fe oxides. In the case of larger additions of Fe, the treatment at 300°C resulted in a considerable decrease in the total and external surface areas and swelling capacity of the sample and in the formation of a network of large-size pores, in which all the pores were connected.