Fluoride Removal from Aqueous Solution Using Chitosan Adsorbent

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.