Fluoride Removal from Aqueous Solutions by NaOH-Modified Eucalyptus Leaves

Introduction: Fluoride (F) and its compounds are widely used in industries in which fluoride overdose leads to various detrimental diseases. In this study the effect of NaOH-modified Eucalyptus leaves on fluoride removal from aqueous solutions as a natural adsorbent was investigated. Materials and Methods: The focus of this study was on the effects of parameters such as pH (2-12), initial concentration (5-30 mg/L), adsorbent dose (0.1-1 g/L) and temperature (25-45 0C). Fluoride residual was measured using the SPADNS method by a DR 5000 spectrophotometer. Results: The maximum adsorption capacity, at pH 2 was found to be 97 mg F/g with an adsorbent dosage of 0.5 g/L and an initial fluoride concentration of 20 mg/L. The adsorption equilibrium and kinetic data were in good agreement with Langmuir Model (R2 = 0.967) with qmax = 298 mg/g and pseudo-second order reaction (R2 = 0.999). Conclusion: Based on the results, NaOH-modified eucalyptus leaves were found to be able to remove fluoride from aqueous environments with good removal efficiency and adsorption capacity.