Fluoride Removal by Alumunium Impregnated Rice Husk Carbon

K. Srinivasan

Department of Chemistry, College of Engineering, Salem-636011 (India)

Evaluation of performance of Alum impregnated Rice Husk Carbon (AIRHC) and commercial activated carbon (AICAC) under batch studies showed a removal of fluoride ion of 88% and 73% respectively. The optimum pH was found to be 4.0-8.0 in the case of AIRHC and 6.0-8.0 for AICAC. The sorption capacity for AIRHC under wet conditions was found to be 4 times higher than AICAC by using Freundlich adsorption isotherm. The ratio of surface area of AIRHC to AICAC was also found to be 3.15 which explains higher removal capacity of AIRHC. Breakthrough capacities of both carbon under column experiments showed that AIRHC was capable of removing fluoride from water 10 times more than AICAC. Moreover capacities of both carbons are not very much affected in the presence of large amounts of bicarbonates and chlorides. However sulphates at a lower concentration affect the capacities to an extent of 50% and 30% respectively. The extent of particle disintegration was also found to be nil for both carbons. A tentative mechanism of fluoride removal and cost of preparation of aluminium loaded carbon is also discussed.

Activated carbon; Fluoride removal; Sorption capacity