Modified bentonitic clay minerals as adsorbents of CO, CO2 and SO2 gases

The adsorptions of CO, CO2 and SO2 gases by two bentonitic clay minerals from Patagonia, Argentina, in their natural state and after acid treatments, were analyzed. The clay minerals (bulk and <2 mum size fraction) were modified with 3.0 and 6.0 N HCl solutions at boiling temperature during 3 h. The samples were characterized by chemical analysis, X-ray diffraction and by N-2 adsorption-desorption isotherms. Equilibrium adsorption of the gas was measured at 25 degreesC and 1 kg/cm(2). Gas adsorptions by bentonitic clay minerals increased after acid treatments and the values were analyzed as a function of structural and textural changes. The retention values of the SO2 (0.636-1.232 mmol/g) by clay minerals were higher than CO2 (0.218-0.516 mmol/g) and CO (0.075-0.119 mmol/g). A high smectitic component in the original clay mineral, an increase in BET surface and micropore volume and an increase of the Si/(Al + Fe + Mg + Ti) ratio of the materials after acid treatments influenced to get a larger retention of the CO2 and SO2 gases. ((C)) 2002 Elsevier Science Inc. All rights reserved.