The effect of exposure of Wyoming bentonite to glacial acetic acid has been studied by F.t.i.r., X.p.s, SEM and acidity measurements, in order to investigate the possibility of using such a non-aqueous technique as an alternative activation process. Treatment with glacial acetic acid, results in an overall increase in the concentration of acid sites. However, the number of Brarnsted sites is reduced, whereas the population of Lewis sites increases. This change is accompanied by the leaching out of A13+, but with no extensive loss of crystallinity. Treatment with mineral acids results in an increase in Bronsted acidity.

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The surface of a highly crystalline calcium hydroxide sample consisting of thin hexagonal plates was modified by a two-step reaction, so that the majority of surface OH groups were replaced by nitrobenzamide silane groups. This reaction formerly carried out on silica gel surfaces, occurs here to a larger extent because of the lack of porosity, and because of the basic nature of the Ca(OH), hydroxide groups. The reaction only occurs on the free surface of the crystallites leaving their morphology largely intact. This example of a functionalised calcium hydroxide composite has been characterised by spectroscopic and thermal methods, and by scanning electron microscopy.

Radionuclides ¡Radioactive contamination /Sorption /Surface coatings SummaryThe sorption of radionuclides by painted surfaces from aqueous solutions of different pH has been measured by an immersion technique at 298.2 K. This approach has distinct advantages over decontamination procedures used previously. The sorption of a metal-ion species is related to its basicity ; the charges on radiocolloids and on the surface coating are also of consequence. Results are presented for the take-up of radioactive caesium, cobalt, hafnium, scandium, and zinc by epoxide, urethane, and chlorinated rubber paints.