Adsorption isotherm describes the experimental sorption
data, adsorption mechanisms, surface properties, and
affinity of an adsorbent towards heavy metal ions (Ho et al.
2002). It is an expression that shows the relationship
between the amount of adsorbate adsorbed per unit weight
of the adsorbent (qe, mg g-1) and the concentration of the
adsorbate in bulk solution (Ce, mg L-1), at a given temperature
under equilibrium conditions. Values of the
experimental results were analysed with Langmuir (1918)
(Eq. 4) and Freundlich (