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Removal of Fluoride from Drinking Water Using Protonated Glycerol Diglycidyl Ether Cross-Linked Chitosan Beads

In this study, physically and chemically modified chitosan; protonated glycerol diglycidyl ether cross-linked chitosan beads (GDCLCB/H+) were prepared and characterized using FTIR and SEM. The optimum defluoridation capacity (DC) of GDCLCB/H+ was observed at the initial F- ion concentration of 15 mg/l, adsorbent dosage of 0.6 g, contact time of 30 min and pH of the solution was in the range of 5–7 at 303 ± 2 K. The equilibrium adsorption data fitted well with Langmuir and Freundlich isotherm models. The maximum adsorption capacity (q0), obtained from Langmuir isotherm for F-adsorption was found to be 2000 mg/kg, which was significantly higher than that of unmodified chitosan (192.3 mg/kg) and most of the chitosan-based sorbents reported in the literature. Water samples collected from Medawachchiya, Sri Lanka, were treated with the adsorbents and the results suggested that GDCLCB/H+ could be used as an effective defluoridation agent.