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International Journal of Environment Science and Technology
Center for Environment and Energy Research and Studies (CEERS)
ISSN: 1735-1472 EISSN: 1735-1472
Vol. 12, No. 11, 2015, pp. 3563-3574
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Bioline Code: st15334
Full paper language: English
Document type: Research Article
Document available free of charge
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International Journal of Environment Science and Technology, Vol. 12, No. 11, 2015, pp. 3563-3574
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Adsorption studies of toxic metals and dyes on soil colloids and their transport in natural porous media
Murali, R.; Murthy, C. N. & Sengupta, C. N.
Abstract
Mobile colloids in soils and aquifers can act
as carriers for adsorbed contaminants and thereby facilitate
the transport of contaminants. In order to understand
the problem, colloids isolated from soil were used
as adsorbents for toxic metals such as Pb(II), Ni(II),
Cu(II), Cr(VI) and dyes such as alizarin red and methylene
blue. Column experiments were conducted to
investigate the mobilization of in situ colloids from soil
and their size distribution. Experiments were also conducted
to study the transport of alizarin red dye through
soil columns at different ionic strengths (0.01 and
0.001 M) and pH (pH 7.5, 9.5 and 11.5) and toxic
metals at the ionic strength of 0.001 M. The colloids
showed significant adsorption toward the contaminants
with the adsorption of methylene blue reaching as high
as 625 mg g-1. The mobilized colloids had significant
difference in their size distribution, and the cumulative
mass curve of colloids followed a nonlinear pattern in
contrast to the previously reported linear behavior on
model systems. The dye and toxic metal transport
experiments suggested their sensitivity to low ionic
strength influent solution, with the capacity of colloids
to transport the dye and toxic metals increasing at low
ionic strength and the transport of dye at high pH. With
decreasing ionic strength, the release rate coefficient of
dye increased. This study represents an important step to
understand colloid-associated contaminant transport in
natural soils.
Keywords
Adsorption; Dye contaminant; Flocculation; Ionic strength; Soil colloids
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