where qe is the adsorption capacity at equilibrium (mg/g), qmax is the maximum adsorption capacity
(mg/g), KL is the Langmuir equilibrium constant related to the affinity of binding sites and energy of
adsorption, and Ce is the equilibrium solution concentration (mg/l). According to Bouhamed et al. [17]
the essential features of the Langmuir isotherm can be expressed in terms of separation factor or
equilibrium parameter RL that can be calculated from the relationship :