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Sorption of lead by chemically modified rice bran
Fatima, T.; Nadeem, R.; Masood, A.; Saeed, R. & Ashraf, M.
Abstract
In this work, the effectiveness of native and
chemically modified rice bran to remove heavy metal Pb(II)
ions from aqueous solution was examined. Chemical
modifications with some simple and low-cost chemicals
resulted in enhancement of the adsorption capacities and
had faster kinetics than native rice bran. Experiments were
conducted in shake flasks to monitor the upshot of parameters over a range of pH, initial Pb(II) concentrations and
contact times using a batch model study. The sorption
capacities
q
(mg g
-1
) increased in the following order:
NaOH (147.78), Ca(OH)
2
(139.08), Al(OH)
3
(127.24),
esterification (124.28), NaHCO
3
(118.08), methylation
(118.88), Na
2
CO
3
(117.12) and native (80.24). The utmost
uptake capacity
q
(mg g
-1
) was shown by NaOH-pretreated
rice bran. The results showed that, using NaOH-modified
rice bran, the chief removal of Pb(II) was 74.54 % at pH 5,
primary Pb(II) concentration 100 mg L
-1
and contact time
240 min. Equilibrium isotherms for the Pb(II) adsorption
were analyzed by Langmuir and Freundlich isotherm
models. The Langmuir isotherm model, showing Pb(II)
sorption as accessible through the high value of the correlation coefficient (
R
2
=
0.993), showed a
q
max
value of
416.61 mg g
-1
. The kinetic model illustrated adsorption ates well, depicted by a second order, which gives an
indication concerning the rate-limiting step. Thermodynamic evaluation of the metal ion
δ
G
°
was carried out and
led to the observation that the adsorption reaction is spontaneous and endothermic in nature. NaOH chemically
modified rice bran was a superb biosorbent for exclusion of
Pb(II) and proved to be excellent for industrial applications.
Keywords
Equilibrium isotherm; Gibbs free energy; Industrial wastewater; Pretreatments
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