Analytical expressions for the isosteric heat of adsorption from commonly used adsorption isotherms models and 2D equations of state

The isosteric heat of adsorption or differential enthalpy of adsorption is a valuable thermodynamic property for the design of adsorption processes that represents a measure of the adsorbate-adsorbent strength of interaction.... [ view full abstract ]

The isosteric heat of adsorption or differential enthalpy of adsorption is a valuable thermodynamic property for the design of adsorption processes that represents a measure of the adsorbate-adsorbent strength of interaction. In this paper we present analytical expressions for isosteric heat obtained for a variety of commonly used adsorption isotherms, including 2D fluid equations of state based on perturbation theory using the square-well (SW) model within the SAFT-VR-2D framework. Applications are presented for the modeling of adsorption of N2O on biochar (BC-60). The use of biochar to reduce greenhouse emissions, and in particular N2O, has attracted a lot of attention despite the controversies on the mechanism for the reduction of emissions. We present the prediction of adsorption isotherms and an expression to reproduce the surface area for this system for a whole range of temperatures, that depend on two constant parameters only.

We are grateful for the support of the Royal Academy of Engineering Newton Research Collaboration Programme (3) - NRCP1516/1/124 for this work