(198c) Assessment of Defluoridation of Drinking Water Using Novel Adsorbent Nano-Crystalline Magnesium Amended Hydroxyapatite (M-HAP)

In the past few decades, fluoride contamination in drinking water has raised a great concern in the society as the earlier considered essential element fluoride turned into a major deleterious contaminant. According to World Health Organization the specified permissible limit of fluoride concentration inconsumable water is 1.5 mg/L. Intake of fluoride into body in excessive amount (>1.5mg/L) causes adverse health effects such as dental and skeletal fluorosis and toxicity at molecular level. Endemic fluorosis is now known to be global in scope and occurring on all continents and millions of people are suffering the consequences.Water fluoridation has been banned in many countries including China, Austria, Belgium, Finland, Germany, Denmark, Norway, Sweden, the Netherlands, Hungary, and Japan. To counteract the effect of fluoride, anovel adsorbent was synthesized using chemical precipitation method and named asMagnesium amended hydroxyapatite (M-HAP) that can be used for defluoridation of fluoride water. Characterization of M-HAP was performed via XRD, FTIR and TEM/EDX to analyze the structural composition, bonding patterns and micro-structural details respectively. The nano-crystalline structure (7-10nm) of M-HAP was confirmed through these studies. The defluoridation potential of M-HAP was investigated for defluoridation capacities through batch equilibrium experiments to gain insight of adsorption behavior, kinetics and mechanisms of adsorption of fluoride ion. The effect of various physicochemical parameters such as pH, adsorbent dose, initial fluoride concentration and the presence of interfering co-ions on adsorption of fluoride has been investigated. It was found that the adsorbent is very effective  for  defluoridation  of  drinking  water  with  a maximum fluoride  uptake  capacity  of  1.16mg/g achieved within 180minutes.  Sorption process was found to be independent of pH and altered in the presence of other co-existing anions. The mechanism of adsorption is governed by Langmuir model and hence is monolayer in nature. The adsorption process follows pseudo-second-order and intraparticle diffusion kinetic models. Water quality parameters tested after treatment of fluoridated water with M-HAP indicates that the TDS, turbidity, hardness and total alkalinity are under permissible limit of standard drinking water regulations.