Equilibrium and heat of adsorption for water vapor and activated carbon

The Qi-Hay-Rood adsorption isotherm equation is shown to provide an improved description of equilibrium water vapor adsorption onto microporous activated carbon between 298 and 373 K and total pressure at 101 kPa, when compared with an existing isotherm model. The influence of temperature on the isotherm equation's parameters is also quantified. An expression for the isosteric heat of adsorption is derived from the Clausius-Clapeyron equation. It is shown that the isosteric heat of adsorption decreases with increasing temperature and increasing adsorption capacity of water vapor. This new isotherm model can be inverted to describe water vapor concentration dependence on adsorption capacity and is therefore well suited for use in dynamic models for activated-carbon adsorption systems.