Adsorption of gas mixtures

Summary

• 1. A new volumetric-gravimetric method for the measurement of simultaneous adsorption from binary mixtures of gases or vapors on solid adsorbents is described.

• 2. Measurements have been made of simultaneous adsorption from mixtures of H₂O and C₂H₅Cl on active charcoal at 74° over a range of relative pressure of water vapor of 0–0.85 and over a range of partial pressures p₂ of ethyl chloride of 0–180 mm Hg.

• 3. The adsorption isotherms for water at constant p₂ are displaced by rise in the value of p₂ to the right from the origin, and the steepness of their linear middle sections increases.

• 4. Rise in relative pressureh of water vapor to above 0.5 at constant partial pressure of ethyl chloride leads to a sharp fall in the sorption of ethyl chloride. With further rise inh, the ethyl chloride is practically completely displaced from the charcoal by water.

• 5. An examination has been made of the stoichiometry of adsorptional displacement in the adsorption of binary gas mixtures, It has been shown. that on the basis of Langmuir's theory, the displacement coefficient γ should tend to unity as the pressure increases, It has been found that in the adsorption of mixtures of H₂O and C₂H₅Cl on charcoal at high pressures γ approximates to the value 5, so that in adsorptional displacement five H₂O molecules are equivalent to one C₂H₅CI molecule.

• 6. The difficulties arising in the interpretation of the results from the point of view of the concept of capillary condensation of water in the given system are pointed out, and one of the other possible mechanisms of adsorption of water on charcoal is examined: it is based on the hypothesis of two-dimensional change of state in the adsorption layer resulting from the formation of hydrogen bonds between adsorbed water molecules.