Abstract:
A number of low cost waste sorbent
have been used for removal of heavy metals, however,
few studies have been carried out on the
sorption process on riverbed sediments in their
natural state of occurrence. Stream sediments adsorb
certain solutes from streams, thereby significantly
changing the solute composition, but little
is known about quantitatively describing sorption
phenomena and rates of these processes. In the
present investigation, sorption of lead ions on
river bed sediments of river Hindon, a tributary of
river Yamuna, India has been studied to demonstrate
the role of bed sediments in controlling
metal pollution. The effect of various operating
variables, viz., initial concentration, solution pH,
sediment dose, contact time and particle size has
been studied. The sorption of lead ions increased
with respect to pH and sorbent dose and decreased
with sorbent particle size. Two important
geochemical phases, iron and manganese oxide,
also play important role in the sorption process.
The sorption data were analysed using Langmuir and Freundlich isotherm models to determine the
mechanistic parameters related to the sorption
process. Further, although lead ions have more
affinity for the fine fraction of the sediment, but
the overall contribution of coarser fraction to
sorption is more as compared to clay and silt
fraction. The kinetic data suggest that the sorption
of lead on bed sediments is an endothermic
process, which is spontaneous at low temperature.
The uptake of lead is controlled by both bulk and
intraparticle diffusion mechanism.
