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

CHAPTER 1
INTRODUCTION
1.1. Environmental Considerations
Biosorption is emerging as an alternative technology to remove the toxic
and pollutant species from aqueous media. To understand the feasibility of the
biosorption processes for the removal of toxic metals, it is needed to investigate the
modelling of biosorption, and also to test the biosorbent with the industrial effluents.
In this study, some new biosorbent materials like algae are presented for commercial
utilization owing to the comprehensive research and economical advantage of
biosorption.
1.2. Heavy Metals
The term ‘heavy metal’ can be defined in different ways; one is that the metal
has a higher density and can have a potential toxicity even if it has a lower
concentration, e.g. Ni. Another definition is that it includes the transition metals,
some metalloids, lanthanides and actinides which can show metallic properties. Lead,
Cd, Zn, Cu and Hg can be given as the examples of heavy metals.
Some heavy metals like Cu, Zn, Se, Fe and Ni are essential elements which
are required for maintaining the metabolism of all living organisms. They are used as
co-factors for enzymes or proteins but they are needed in very small amounts.
Cadmium, Hg, and Pb are among the non-essential metals. Based on their
concentration, not only the essential but also the non-essential metals play a role as
cell toxins. This phenomenon comes from the unspecific binding of the metals to
important biomolecules and proceeds with:
· blocking of functional groups,
· displacement of essential elements,
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