The Pickett equation analytical continuation

Abstract

Usually gas adsorption isotherms are evaluated by means of the classic two-parameter equation of Brunauer, Emmett and Teller (BET II). This equation however fails when multilayer adsorption or capillary condensation occurs. The present work suggests the use of the three-parameter Pickett equation in the range of high adsorptive pressure of the gaseous phase. An analytical continuation of the Pickett equation allows for the description of the whole isotherm. Adsorption isotherms of krypton, water vapor, and n-heptane at Lunar regolith samples are evaluated using both, BET II and continued Pickett equation. © 2011 Springer-Verlag.