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

such as 10.0, 20.0, 50.0, 100.0, and 200.0 mg were shaken with 10.0 mL solution of
250.0 mg metal/L at 25ºC for 60 min, and the results are given in Figure 3.14-3.17. The
results showed that the percentage sorption of Pb 2+ ions by Dunaliella salina increases
20.0 mg biosorbent dose, then it stays constant from 20.0 mg to 200.0 mg biosorbent
dose. The percentage uptake of Pb 2+ ions by Oocystis sp., Porpyridium cruentum, and
Scenedesmus protuberans, shows an exponential growth. Cd 2+ and Ni 2+ sorption is
lower in comparison with Pb 2+ . A relationship can also be given between a biomass
amount and sorption due to the fact that the availability of the metal ion might be
limited with increased electrostatic interactions, interference between binding sites, and
reduced mixing at higher biosorbent dose. Furthermore, electrostatic interactions
between cells could be considered as significant for the biomass-dependent metal
uptake. With a large amount of metal ion which is biosorbed if the distance between the
cells is greater, otherwords lower amount of biosorbent is used which is enough for the
sorption takes place. Even though an increased biosorbent dose has an reducing role on
the sorption capacity of a biosorbent, and in this study, the total removal of metal ion by
a biosorbent is higher at higher biosorbent dose. Hence, this behaviour can be explained
that there is no such a correlation between biosorbent amount and metal removal
(Madrid and Camara 1997).
Sorption (%)
100.0
80.0
60.0
40.0
20.0
0.0
10.0
20.0
50.0
100.0
biosorbent amount (mg)
200.0
Pb
Cd
Ni
Figure 3.14. Effect of biosorbent amount on biosorption of Pb 2+ , Cd 2+ , and Ni 2+ by
Dunaliella salina (10.0 mL solution of 250.0 mg/L, solution pH of 6.0,
sorption time of 60 min, and different amounts of biomass)
Ni
Cd
Pb
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