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A novel biosorbent was developed by
the crosslinking of an anionic biopolymer, calcium alginate (CA),
with perchloric acid (PCA). The PCA cross-linked was characterized
by Fourier-transform infrared, scanning electron microscopy (SEM),
transmission electron microscopy, X-ray diffraction, and surface
area analysis. Experimental parameters affecting the adsorption
process such as pH, agitation time, concentration of adsorbate, and
amount of adsorbent were studied. Langmuir and Freundlich isotherms
were used to fit the experimental data. The best interpretation for
the equilibrium data was given by the Langmuir isotherm. The maximum
adsorption capacity for fluoride was 44 mg/g based on the Langmuir
equation at a temperature of 28°C, a solution pH of 3.0, a adsorbent
dosage of 0.7 g/100 mL, and a contact time of 120 min. The
experimental data were analyzed using three sorption kinetic models,
namely, pseudo-first-order, pseudo-second-order, and intraparticle
diffusion model. Results show that the pseudo-second-order equation
provides the best correlation for the adsorption process. The
findings of the present study indicate that PCA can be successfully
used for the removal of fluoride ions from aqueous solutions. |
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Key words: Perchloric acid,
Defluoridation, Adsorption, Isotherms, Kinetics. |
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