metals are highly toxic or Eco toxic properties including cobalt, copper; manganese, molybdenum, and
zinc, arsenic, cadmium, lead, mercury, manganese, zinc chromium etc. cannot be
degraded and destroyed because of their solubility in water and hence it gets
consumed by life forms by three pathways via eating food, drinking water, and
inhaling air. There are some essential heavy
metals like Iron, Chromium Zinc, Cadmium and Cobalt are nutrients that are required
for normal body growth of living organism in small amounts. At specific amount
is needed for normal body function; while excessive amounts can be detrimental
to the normal body function of organisms, including kidney damage, creation of
mutations, nervous system and induction of tumors.
Heavy metals exist within the natural components of
the earth’s crust and become concentrated as a result of human caused
activities. Heavy” in conventional usage implies high density and “Metal” in
conventional usage refer to the pure element or an alloy of metallic elements.
Heavy metal has a high density range from 3.5g/cm3 to above 7g/cm3 and the
atomic weights of heavy metal between 63.5 and 200.6 and specific gravity at
least 5 times more than water. They are usually present in the periodic table
as transition metals but not all the transition metal that have a heavy metal.
Some of the f-block elements are also heavy
metals and they sometimes called trace elements. The element that are usually
found in the water form oxides and such elements are called oxyanions.
With the expansion of population and industry, there
has been considered increase in the discharge of excess amount of heavy metals
into the environment has posed a real challenge facing towards modern world. The removal of heavy metals from the
environment is of special concern due to their persistence (Mona Karnib et al.
2014). Several methods are used for removing of heavy metal from water like
Nano remediation, bioremediation, phytoremediation, chemical precipitation,
adsorbents, Nano filtration and reverse osmosis etc.