141. BALY, E. C. C., PEPPER, W. P., AND VERNON, C. E. Adsorption of Hydrous Metallic Oxides by Kieselguhr. Trans. Faraday Soc., vol. 35, 1939, pp. 1165-1175; Chem. Abs., vol. 33, 1939, p. 9084.
Method is described for purifying kieselguhr: The clay and part of the organic matter were removed by repeated extraction with hot 4 N HCl, the last traces of organic matter being oxidized by heating the extracted kieselguhr at 600° in a current of air for 8 hr. The purified kieselguhr was remarkably constant in its properties. It showed a surface area of 2,869X106 cm.2 per 100 gm. It adsorbs the anhydrous oxides of Al, Th, Ni, and Co. The adsorbate in each case is activated (shown by enhancement of the ζ-potential) as the result of the formation of adsorption complexes. Al2O3 and ThO2 form a single unimolecular layer, with Ni and Co oxides, 3 unimolecular layers are adsorbed together, forming 1 layer of crystal unit cells. When a mixture of Ni and Th oxides (1 ThO2:24 NiO) is adsorbed, 1 out of every 7 groups of 4 Ni and 4 O in each of the 3 layers of the crystal lattice is replaced by a molecule of ThO2. This is also true when CoO is substituted for NiO. The effect of the adsorbed layer of metallic oxide was determined by measuring the surface potential by cataphoresis methods.
BANDEL, G. See abs. 3323.