ADSORPTION KINETICS OF DEFLUORIDATION BY ACTIVATED ALUMINA

Abstract

The availability of water depends on the quality of water in various sources, whether ground water or surface water. The presence of fluorides in water- acts as two edge sword. - It is necessary to keep the fluorides in drinking water within recommended limits. One of the recommended method for fluorides removal is adsorption by activated alumina. In present study, the kinetics. of fluoride removal by adsorption on activated alumina and effects, of various parameters on its efficiency have been evoluted. A modified first order kinetics equation has been suggeSted for better. representation of adsorption kinetics. Batch studies by activated alumina were performed taking into account the variables like grain size, ratio of adsorbate to adsorbent (F o /X o), pH, HCO3 - alkalinity. It is observed that removal is directly. related to the concentration-of.fluoride which is aboveaftllibrium fluoride 4 ')"4,;) cif °"k!'!:14 level. 0( ..• ) 10)4 4 • The removal capacity, removal rate ancrcliMf life were found to be affected by all the parameters mentioned. The trend how these variable affect, the removal rate, capacity and half life have been presented in graphical and mathematical form. According to present study, it is found that the pH and, (F o /X o), affects the defluoridation significantly. It is concluded from this study that acidic activated alumina is better to use. It is also inferred that Langmuir isotherm is better to represent the adsorption model for fluoride removal by activated alumina. According this isotherm the maximum removal capacity is found to be 7.692 mg F /g Alumina.