The Journal of

Introduction: Control of fluoride concentration in drinking water due to health effects is very important. The potential of Cuttlefish bone (CB) as a natural sorbent and the effects of pH, contact time, fluoride concentration and adsorbent dosage for the adsorptive removal of excess fluoride from water were examined.

Methods: The study was carried out in laboratory scale via batch reactor. The CB was crushed and pulverized by standard ASTM sieves. The chemical composition and solid structure of CB was determined using X-ray diffraction (XRD) and scanning electronic microscopy (SEM). Measurement of the surface area was carried out via N₂ gas adsorption and BET isotherm. The concentration of fluoride was measured by SPADNS method and spectrophometry on 570 nm. Isotherm and adsorption capacity was determined by Langmuir, Freundlich and Temkin adsorption models.

Results: The main component of CB is CaCO3 which has 5.36 m²/g surface area. The results indicated the following: 120 minimum contact time, neutral pH, 15 g/l of sorbent and 7 mg/l of fluoride concentration led to 52.2 % of fluoride removal increasing adsorbent dosage from 15 to 45 g/l led to increasing fluoride removal up to 75.2%. The adsorption data conform to Langmuier model (R²=0.997) in which maximum adsorption capacity was 1.64mg/g and dimensionless coefficient of R_L and b was 0.76 and 0.063 L/mg, respectively. Based on Freundlich model the coefficient of n and k was found to be 0.9 and 0.08, respectively.

Conclusion: Increasing of contact time, fluoride concentration, adsorbent dosage and pH decreasing led to enhancing fluoride adsorption.