where the subscripts exp and cal refer to experimental and calcu-lated data, respectively, and p is the number of experimental data.
An average relative error smaller than 13% indicates that the model
closely fitted the experimental results [24].
The Langmuir adsorption isotherm (Fig. 6a), which assumes that
the adsorption occurs at specific homogeneous sites within the
adsorbent and which has been successfully applied to many mono-layer adsorption process [25], can be written using the following
linearized equation