A Study of the Influence of Adsorbed Water on Low Temperature Physical Adsorption of Propane on the Surface of Quartz

Adsorbed water on adsorbent influences seriously on the adsorptive character of the adsorbent. To investigate the influence, low temperature physical adsorption of propane on quartz and on the surface of water adsorbed on the quartz has been volumetrically measured. The energy difference, E1-EL, in BET equation and isosteric heats of adorption, qst, have been calculated using the isotherms obtained.It was found that the values of (E1-EL) are on the decrease with the increase of molecular layers of water adsorbed on the quartz, and they finally approach the constant value of about 3.06 kJ/mole. The behavior of the molecule of propane adsorbed on the quartz and on the surface of water adsorbed on the quartz is discussed in this paper using the values of qst obtained. With the increase in the volume of adsorbed propane, the adsorbing state of propane changes from a gaseous film to an expanded liquid film and finally to an intermediate liquid film.The vapor-pressure curve of propane at low temperature has been experimentally determined as follows : logp=A-BlogT-C/T, where p denotes pressure in Torr, and T absolute temperature, and A is 13.2586, B 2.19844, and C 1197.14.