In adsorption studies, the energetic values of entropy and
enthalpy in addition to adsorption free energy must be taken in
considerations to determine the adsorption process. Values of
thermodynamic parameters are the actual indicators for practical
applicability of metal ions adsorption process. The amounts of
Cu(II) and Co(II) ions adsorbed by the different biosorbents under
consideration at different temperatures 25, 35 and 45 8C, at
equilibrium have been used to obtain thermodynamic parameters
for the adsorption process. The dependence of Langmuir constant
(kL) with temperature was used to predict the thermodynamic
parameters associated with the adsorption process [33]. The
standard Gibbs free energy change (DG8), standard enthalpy
change (DH8) and standard entropy change (DS8) were determined
by using the following equations: