BIOSORPTION OF Pb2+, Cd2+, & Ni2+ FROM WATERS BY ...

Desorption (%)
Desorption (%)
100.0
80.0
60.0
40.0
20.0
0.0
0.1 M HNO 3
0.1 M HCl 0.1 M Na-citrate
Figure 3.19. Desorption of Pb 2+ , Cd 2+ , and Ni 2+ from Scenedesmus protuberans using
0.100 M HNO3, 0.100 M HCI, and 0.100 M Na-citrate
3.4. Competitive Biosorption: Three-Metal Ion System
Competitive biosorption of Pb 2+ , Cd 2+ , Ni 2+ by the biosorbents were carried out
at three different metal ion concentrations. In the experiments, a 10.0 mg of biosorbent
was allowed to be treated with a 10.0 mL mixed metal ion solution at 25ºC. The results
are given in Table 3.3 - 3.6 with the sorption of a single metal ion system for the sake of
comparison.
In general, the presence of other ions in the solution influences the biosorption
of target metal ion. From the results, at low cocentration of metal ions present in the
mixed system, the biosorption of Pb 2+ , Cd 2+ , and Ni 2+ by all biosorbents does not seem
to be affected much. However, when the concentration of three metal ions in the mixed
solution is raised the percentage sorption declines. In all cases, the removal of Pb 2+ by
all biosorbents from the solution is not influenced, and this result can be due to the
higher selectivity of the biosorbents towards Pb 2+ .
Pb
Cd
Ni
50