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 Al3+ forms by loading respective metal ions in H+ form of resin. The DCs of Na+ and Al3(+) 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 Delta G degrees, Delta H degrees, Delta S degrees, and sticking probability (S-center dot) 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. (C) 2008 Elsevier B.V. All rights reserved.