HEATS OF IMMERSION OF MICROPOROUS SOLIDS

Publisher Summary The heats of immersion are measured in a thermistor-type adiabatic calorimeter. The heat decreases to a plateau after approximately 25% of the micropore volume is filled. It decreases again after 80% micropore volume filling. The heat of immersion of carbosieve as a function of pre-coverage of 2-propanol gradually decreases up to 34% volume filling. The mechanism of adsorption of water, methanol, and 2-propanol is via the van der Walls forces between the propyl backbone and the polystyrene surface. Mechanism for 2-propanol adsorption is different from that of water and methanol, leading to a Type I isotherm. On the other hand, the mechanism of adsorption of both water and methanol is confirmed by the heat of immersion measurements and the resulting differential heats of adsorption. The ratio of energy of adsorption in the micropore to the energy of adsorption on the external surface is zero when the diameter ratio is 0.93:1. When this ratio is less than 0.93:1, the condition for micropore filling is no more favorable than for adsorption on the external surface.