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Abstract
Aim:
To explore the potential of water hyacinth biomass as a low cost adsorbent
for sequestrating chromium ions from aqueous solution.
Methodology: The biosorption behavior of chromium ions (Cr(III)
and Cr(VI)) from aqueous solution by powdered water hyacinth biomass was
assessed through series of batch experiments using advanced instrumentation
techniques like Scanning Electron Microscopy with Energy Dispersive X-ray
analysis and Fourier Transform Infra-Red spectroscopy, pH zero point charge.
The equilibrium relationship between sorbent and sorbate was determined in
solution by using the isotherms Langmuir, Freundlich and Temkin models.
Results:
The optimum pH for Cr(III) and Cr(VI) adsorption was 5.0 and 2.0 whereas the
maximum Cr(III) and Cr(VI) adsorption was 99.80 and 89.15%, respectively.
Langmuir isotherm fitted the data well with R2 value of 0.999 for
both Cr(III) and Cr(VI) by the biosorbent. Adsorption kinetics showed
that the experimental data fitted the pseudo second order kinetic model with
R2 value of 0.999 for both Cr(III) and Cr(VI). The EDX spectra
peaks of Ca, O, C indicated the presence of functional groups such as –OH and
–COOH in the biosorbent. The zeta potential analysis depicted that water
hyacinth biomass had negative surface charge of (-) 23.5mV.
Interpretation: Water hyacinth based biosorbent can be
utilized for the removal of Cr ions from industrial waste water. Further,
water hyacinth has additional advantage that it reduces or even eliminates
the diverse impact of weeds on the environment.
Key
words:
Biosorption, Chromium removal, Water hyacinth
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