Activation energy is an important parameter in a thermodynamic study as it determines the
temperature dependence of the reaction rate. In chemistry, activation energy is defined as
the energy that must be overcome in order for a chemical reaction to occur. In adsorption
separation, it is defined as the energy that must be overcome by the adsorbate ion/molecule
to react/interact with the functional groups on the surface of the adsorbent. It is the
minimum energy needed for a specific adsorbate-adsorbent interaction to take place, even
though the process may already be thermodynamically possible. The activation energy of a
reaction is usually denoted by Ea, and given in units of kJ mol-1. The activation energy (Ea)
for the adsorption of an adsorbate ion/molecule onto an adsorbent surface in an adsorption
process can be determined from experimental measurements of the adsorption rate constant
at different temperatures according to the Arrhenius equation as follows: