Synthesis of Zr(IV) entrapped chitosan polymeric matrix for selective fluoride sorption

The Zr(IV) loaded carboxylated chitosan beads (Zr-CCB) was synthesised and fluoride removal studies were carried out in batch equilibration method. The results shows an enhanced defluoridation capacity (DC) of Zr-CCB (4850 mg F−/kg) than the carboxylated chitosan beads (CCB) and raw chitosan beads (CB) which possesses the DCs of 1385 and 52 mg F−/kg, respectively. The mechanism of fluoride removal by Zr-CCB is governed by both adsorption and complexation. The presence of functional groups, elements and the surface morphology of the sorbent were confirmed by FTIR and SEM with EDAX analysis. The experimental data have been analysed using Freundlich, Langmuir and Dubinin-Radushkevich (D-R) isotherms. The best fit isotherm model was identified using various methods of non-linear analysis. Thermodynamic parameters such as ΔG°, ΔH° and ΔS° were calculated to predict the nature of fluoride sorption. A field trial was carried out with fluoride water collected from a nearby fluoride-endemic village.