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Authors
Info
I. Rehmat, X. Meng*,
J. Wang and Z. Mu? ?
School of Chemical and
Biological Engineering,
Lanzhou Jiaotong
University-730 000, Gansu, China
*Corresponding
Author Email :
Mengxg1@163.com
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Abstract
Aim: To study the
contrasting effect of adsorption and removal of cadmium ions using wheat
straw biochar, rice straw biochar and attapulgite clay in contaminated
aqueous solution.
Methodology: Batch sorption
experiment was carried out to investigate the parameters influencing the
adsorption capacity such as pH, initial cadmium concentration, adsorbent dose
and contact time. The physical and chemical characteristics of biochars and
clay were studied and adsorption mechanism was analyzed by scanning electron
microscopy, infrared spectroscopy, Brunauer-Emmett-Teller and X-ray
diffraction, which indicated high adsorption and removal of Cd+2ions
by wheat straw biochar was mainly due to the presence of surface carboxyl
functional groups ?OH, C-O, COOH that reacted Cd2+ions.?
Results: The adsorption
effect of wheat straw biochar (WSB), rice straw biochar (RSB) and attapulgite
(ATP) clay were compared. The results showed that adsorption isotherms were
best fit to Langmui isotherm model. The adsorption kinetics study well
matched with pseudo second order model and the maximum adsorption equilibrium
of WSB, RSB and ATP reached to 100, 160, and 120 min, respectively. The
results showed that adsorption rate was maximum at pH 6 with 0.1 g dose of
adsorbent, 40 mg l-1 metal concentration, and contact time of 100
min at 30?C for WSB. The maximum percent removal of cadmium ions
from aqueous solution was in the order WSB>ATP>RSB, 95%, 91% and 88%,
respectively.
Interpretation: The results
explored that wheat straw biochar has high Cd2+adsorption rate and
removal efficiency in contaminated water than others. Hence, the results
explored that WSB is a potential, low-cost adsorbent and can be used as
cadmium decontaminant in polluted water with no secondary pollution.
Key words: Attapulgite, Adsorption isotherm, Biochar, Cadmium ions,
Kinetics
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