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Adsorptive removal of cobalt ions on raw and alkali-treated lemon peels
Singh, S. A. & Shukla, S. R.
Abstract
Batch-wise biosorption of Co(II) from aqueous
cobalt nitrate solution of different concentrations has been
carried out on raw and NaOH-treated lemon peels. They
were characterized by Fourier transform infrared spectroscopy,
scanning electron microscopy, energy-dispersive
X-ray spectroscopy, thermogravimetric analysis and Brunauer–
Emmett–Teller surface area analysis. The influence
of biosorbent dose, pH, contact time and temperature on
the adsorption process has been studied. Maximum adsorption
was observed at pH 6. The equilibrium adsorption
on raw and NaOH-treated lemon peels was achieved in 150
and 210 min, the maximum adsorption capacity being
20.83 and 35.71 mg/g, respectively. Energy-dispersive
X-ray spectroscopy and desorption study confirmed that the
mechanism of adsorption is ion exchange. The Langmuir
isotherm and pseudosecond-order kinetic model gave the
best fit for the adsorption of Co(II). The desorption was
found to be more than 96 % using 0.1 N HCl, and the
adsorbent could be reused three times with intermediate
alkaline regeneration stage. Experiments to establish the
effect of competing metal ions on biosorption capacity
were also performed. Thus, NaOH-treated lemon peels
have shown the potential as a good biosorbent for treating
industrial wastewater at low cobalt concentration.
Keywords
Biosorption; Cobalt(II); Langmuir; Pseudosecond order; Synthetic wastewater
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