Defluoridation of water using inexpensive adsorbents

The study assesses the suitability of inexpensive leaf adsorbents to effectively remediate fluoride-contaminated water. The efficiency of the sorption of fluoride ion is affected by pH, contact time, adsorbent dose, type and size of adsorbents and initial fluoride ion concentration. The adsorption equilibrium is well correlated by Freundlich and Langmuir models. Treated leaf powder was studied at various pHs (2, 4, 6 and 8) with a series of aqueous solutions containing 2, 3, 5, 6, 8, 10, 12, and 15 mg F/l. At the highest F-ion concentration (15 mg/l), the F-ion level in the effluent gradually decreased to 0 mg/l within 180 min at 29 +or-.5 degrees C when the dose of adsorbent is 10 g/l in a sample of 50 ml volume. With lower F- ion concentrations (2 mg/l) in the feed solutions the fluoride ion concentration steadily decreased reaching 0 mg/l after 150 min. Langmuir isotherm fits well for defluoridation of water using leaf powder.