From Table I, the k F constant of Freundlich isotherm, which
expresses the selective uptake of copper and affinity of
adsorbent was 13.8995 L/g, whereas the 1/n value was found to
be 0.6473. Generally, the value of 1/n that is related to the
distribution of site bonding energies is ranging between 0.2 –
0.7 [11]. If 1/n is higher than 1, it indicates that the surface
areas of adsorbent covered by the metal ions increase, and the
energies of adsorption will decrease [11].