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Removal of hexavalent chromium from aqueous solution by barium ion cross-linked alginate beads
Uzaşçı, S.; Tezcan, F. & Erim, F.B.
Abstract
Barium ion cross-linked alginate beads have
shown great affinity to toxic hexavalent chromium ions in
aqueous solution, in contrast to the traditionally used calcium
alginate beads. Our adsorption experiments were
carried out by the batch contact method. The optimal pH
for removal was found to be pH 4. The equilibrium was
established in 4 h, and the removal efficiency of chromium(
VI) was found to be 95 %. The adsorption data were
applied to Langmuir, Freundlich, Dubinin–Redushkevich
(D–R), and Temkin isotherm equations. Both Langmuir
and Freundlich isotherm constants indicated a favorable
adsorption. The value of mean sorption energy calculated
from D–R isoterm indicates that the adsorption is essentially
physical. The high maximum chromium(VI)
adsorption capacity was determined from the Langmuir
isotherm as 36.5 mg/g dry alginate beads. The chromium(
VI) adsorption data were analyzed using several
kinetic models such as the pseudo-first-order, pseudo-second-
order, intraparticle diffusion, and Elovich models, and
the rate constants were quantified. Our study suggests that
barium alginate beads can be used as cost-effective and
efficient adsorbents for the removal of chromium(VI) from
contaminated waters.
Keywords
Adsorption; Biopolymer; Chromium(VI); Toxic ion; Uptake
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