For cobalt complexes in neutral and alkaline medium, the
removal percent was decreased by increasing the immersion time
of the biosorbents. That can be attributed to the weak complexation
tendency of cobalt ions and the different biosorbents. Table 1
showed that the concentration of cobalt ions decreased considerably
in the initial time of adsorption process (t = 20 min). While,
the gradual increase in immersion time increase the remaining
concentrations (Ce) of the metal ions after adsorption process. That
can be attributed to the weak Co(II)/biosorbents bonds, which
dissociate after short time of metal complex formation.