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

Figure 3.6. TGA decomposition curve of Scenedesmus protuberans.
Figure 3.6, the decomposition curve of Scenedesmus protuberans, shows that the
mass loss in this alga in the same temperature range is higher than any of the other algae.
As with the others, the first decrement in mass observed in 25ºC-100ºC belongs to the
loss of water and is about 10%.
3.2. Parameters Affecting Biosorption of Pb 2+ , Cd 2+ , and Ni 2+
Apart from the principal parameters affecting biosorption, such as the type and
the form of the biomass and the metal ions, the conditions under which the biosorption
process occurs are accounted on the efficiency of the process. The predominant
parameter of all is the pH of the solution. Moreover, the other factors such as the type
and the amount of the competing ions present also influence the sorption of the analyte
metal ion(s). This situation either increase or decrease the metal uptake.
3.2.1. Effect of Solution pH
Solution pH should be taken into account as one of the most important
parameters that affect biosorption since the pH of the solution may change the form,
thus the chemistry of the target metal ion as well as the binding site(s) on the biomass.
In order to examine the effect of solution pH, sorption experiments were performed at
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