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Abstract--Amorphous derivates prepared by aqueous reaction of various aluminosilicate clay minerals with concentrated KF solution at 80-110~ were studied for their gas adsorption properties. The four clay minerals studied are halloysite, a well-crystallized kaolinite, a poorly crystallized kaolinite, and a montmorillonite. The gases tested are N2, 02, CH4, CO, CO2, and C2H 2. The kaolin-group mineral derivatives are characterized by substantial reduction in particle size, high specific surface, and significant selectivity towards CO2 and CzH 2 relative to the other gases. The montmorillonite derivative shows no increase in adsorption over the starting material, however, for all the materials high adsorption of CO 2 and C2H2 was observed. Levels of gas adsorption and gas adsorption ratios are comparable to pillared clays.

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-Two bentonite clays with different mineralogical compositions from Mendoza, Argentine, were activated with H 2 SO 4 solutions of 4 and 8 N at 90°C for 3.5 hours. This treatment affected clay structural properties, as was shown by thermogravimetry, infrared spectrometry and chemical analysis. Bleaching efficiency for sunflower oil was strongly dependent on the acid concentration used for clay activation. The samples have bleaching capacity comparable to that observed with a commercial adsorbent standard. The mineralogical composition of natural clays influenced the properties of the activated clays.

N 2 and CO 2 gases adsorption by tetramethylammonium(TMA)-montmorillonites and hexadecylpyridinium(HDP)-montmorillonites was carried out using volumetric equipment at 25 °C and 0.1 MPa. The addition of organic compounds to montmorillonites was 1 and 4 times the cation exchange capacity (CEC) of the montmorillonites and the contact times between the TMA (or HDP) and the montmorillonites were 4 and 24 h. The adsorptions of CO 2 by TMA-montmorillonites (0.383-0.477 mmol/g) were higher than those by HDP-montmorillonites (0.027-0.060 mmol/g). N 2 gas retentions by organo-montmorillonites were small: in the range of 0.038-0.065 mmol/g TMA-montmorillonites and around 0.010 mmol/g HDP-montmorillonites. The interlamellar spacing of the organo-montmorillonites, the structure of the intercalated organic molecule, and the type of montmorillonites influenced the gas adsorption values.