Removal of fluoride from drinking water by adsorption onto alum-impregnated activated alumina.pdf

Separation and Purification Technology 50 (2006) 310–317 Removal of fluoride from drinking water by adsorption onto alum-impregnated activated alumina Sushree Swarupa Tripathy a,?, Jean-Luc Bersillon a,1, Krishna Gopal b,2 a Laboratoire Environnment et Mineralurgie, ENSG-INPL, Vandoeuvre Les Nancy Cedex, France b Industrial Toxicology Research Centre, Lucknow 226001, UP, India Received 22 December 2004; received in revised form 24 November 2005; accepted 28 November 2005 Abstract The ability of the alum-impregnated activated alumina (AIAA) for removal of fluoride from water through adsorption has been investigated in the present study. All the experiments are carried out by batch mode. The effect of various parameters viz. contact time, pH effect (pH 2–8), adsorbent dose (0.5–16 g/l), initial fluoride concentration (1–35 mg/l) has been investigated to determine the adsorption capacity of AIAA. The adsorbent dose and isotherm data are correlated to the Bradley equation. The efficacy of AIAA to remove fluoride from water is found to be 99% at pH 6.5, contact time for 3 h, dose of 8 g/l, when 20 mg/l of fluoride is present in 50 ml of water. Energy-dispersive analysis of X-ray shows that t r f ? K 1 c c F i s fi m s c l c t f j ( 1 dhe uptake of fluoride at the AIAA/water interface is due to only surface precipitation. The desorption study reveals that this adsorbent can be egenerated following a simple base–acid rinsing procedure, however, again impregnation of the regenerated adsorbent (rinsed residue) is needed or further defluoridation process. 2005 Elsevier B.V. All rights reserved. eywords: Fluoride; Impregnation; Activated alumina; Adsorption; EDAX; Desorption . Introduction Fluoride is a naturally occurring element in minerals, geo- hemical deposits and natural water systems and enters food hains through either drinking water or eating plants and cereals. luorine and its compounds are valuable and extensively used in ndustry such as fertilisers, production of h