Fluoride Removal from Aqueous Solution Using Chitosan Adsorbent
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Date
2019-06
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Addis Ababa University
Abstract
In this study the extraction of chitosan from fish scale was studied and the performance towards
fluoride adsorption from aqueous solution was evaluated by batch experiments. The methods
used for extraction of chitosan were demineralization, and deproteinization followed by
deacetylation. Proximate analysis, FTIR and XRD analysis were carried out on the obtained
chitosan. Physicochemical properties of obtained chitosan was determined by solubility, water
uptake and oil uptake capacity analysis. The water binding capacity and fat binding capacity and
solubility were found to be 576%, 219.5% and 83.8%, respectively. Degree of Deacetylation was
found to be 84%. The effects of initial fluoride concentration (10, 15 & 20mg/l), adsorbent
dosage (1, 2 & 3gm) and pH of the solution (5, 7 & 9) were analyzed by Design-Expert version
7.0.0 of full factorial versus quadratic model response surface methodology and the optimal
conditions that gave maximum/efficient removal efficiency were selected. The adsorption
capacity of fluoride by chitosan from aqueous solution was found to be 3.248mg/g; and 3gm of
adsorbent dosage, pH value of 7 and 10mg/l initial concentration with 98.47% removal
efficiency were selected as the optimal conditions. The kinetic studies revealed that the data best
fits for pseudo second order regression model and the adsorption process followed Freundlich
isotherm model. The adsorbent after fluoride removal regenerated using 0.1N NaCl aqueous
solution. The results indicate that chitosan adsorbent extracted from fish scale has a good
capability in the removal of fluoride ions from aqueous solution.
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Keywords
Chitosan, Batch experiments, Demineralization, Deproteinization, Deacetylation, Kinetics, Isotherm