The Journal of

Abstract

Introduction:Fluoride is one of the essential elements for human health and presence of its acceptable value prevents from tooth decay but excessive absorption of fluorine into the body cause many chronic problems such as flourosis. The aim of this study was to evaluate the effect of &alpha-Alumina and &gamma -Alumina on removal of fluoride from water.

Methods: This experimental study was performed in laboratory scale and was performed on 182 synthetic samples in a batch system. In this study the effect of parameters such as contact time (10,5,60,45,30,15min), pH(6,7,8), fluoride concentration (1,2,3,4,5,6 mg/l) and absorbent dosages (1,2/5,5,7/5,10 mg/l) was evaluated. Finally the accuracy  rate of information with the Langmuir and Freundlich isotherms was determined.

Results: The results showed that &alpha-Alumina had better efficiency to remove fluoride from water  . fluoride removal efficiency by &alpha-Alumina and &gamma-Alumina were 85% and 72/4%,  respectively at pH of 6, 5 gr/l absorbent dosage, 5gr/l fluoride concentration and 180 minutes time. Investigating absorption isotherm showed that fluoride absorption by &alpha-Alumina and &gamma-Alumina follows Langmuir model.

Conclusion:On the basis of the results, fluoride removal efficiency would decrease with increasing pH and the initial  concentration of fluoride and decreasing alumina mass. Optimum  pH range is  6 to7 and  Maximum absorption occurs in 15 minutes.