Abstract
Various amounts of Na+ ions were exchanged into alumina pillared bentonite (Al-PILB) sample, by controlling the pH of the dispersion of Al-PILB and sodium chloride solution. The Na+ doped pillared clays were calcined at elevated temperatures and adsorption of nitrogen at -196°C, cyclohexane and water at ambient temperature (21 ± 1°C) by the calcined samples were conducted. The results revealed a wide size distribution of the micropores in the pillared clay. Introduction of sodium ions converted the surface of the pore walls from hydrophobic to hydrophilic and blocks some micropores, enhancing water adsorption but reducing nitrogen and cyclohexane adsorption. Existence of Na+ ions in the pores did not improve the thermal stability of the pillared clay. Calcination at high temperatures resulted in a decrease in adsorption capacity. After calcination at 700°C, cyclohexane was inaccessible to the remaining micropores in the Na+ doped pillared clays. The adsorption behavior was clearly related to the cation content as well as the calcination temperature. These results may be useful in developing desiccants and adsorbents from pillared clays for dehumidification and adsorptive cooling applications.[PUBLICATION ABSTRACT]