Effect of contact time
The removal of lead and copper ions increases
with time and attains saturation in about 120 min.
Basically, the removal of sorbate is rapid, but
it gradually decreases with time until it reaches
equilibrium. Fig. 3(a and b) represents the percent
removal of Pb(II) and Cu(II) ions versus the
contact time for the initial concentration and by
using the optimum pH value which was obtained
for the two heavy metals. The two metals showed
a fast rate of sorption during the first 10 min of