Role of metal ion incorporation in ion exchange resin on the selectivity of fluoride.

Indion FR 10 resin has sulphonic acid functional group (H(+) form) possesses appreciable defluoridation capacity (DC) and its DC has been enhanced by chemical modification into Na(+) and Al(3+) forms by loading respective metal ions in H(+) form of resin. The DCs of Na(+) and Al(3+) forms were found to be 445 and 478 mg F(-)/kg, respectively, whereas the DC of H(+) form is 265 mg F(-)/kg at 10 mg/L initial fluoride concentration. The nature and morphology of sorbents are characterized using FTIR and SEM analysis. The fluoride sorption was explained using the Freundlich, Langmuir and Redlich-Peterson isotherms and kinetic models. The calculated thermodynamic parameters such as DeltaG degrees, DeltaH degrees, DeltaS degrees and sticking probability (S(*)) explains the nature of sorption. Comparison was also made by the elution capacity of these resins in order to select a cost effective material. A field trial was carried out to test the suitability of the resins with fluoride water collected from a nearby fluoride-endemic area.