title: Sorption behavior of fluoride ions from aqueous solutions by hydroxyapatite.
abstract: The effects of pH, contact time, fluoride-ion concentration, and the dose of sorbent on the sorption of fluoride ions by hydroxyapatite were studied. Equilibrium was reached in 16 h of contact time and the maximum sorption of fluoride ions was in the pH(eq) range between 5 and 7.3. The highest efficiency in the sorption system was determined by using 0.01 g of hydroxyapatite and 25 mL of solution. The pseudo-second order model described the kinetic sorption processes, and the Freundlich model, the sorption isotherm process. These results indicated that the mechanism was chemisorption on a heterogeneous material. Fluoride ions were partially desorbed using an alkaline solution.
authors.affiliation: Instituto Nacional de Investigaciones Nucleares, Depto. de Química, Apdo. Postal 18-1027, México, D.F., Mexico.
authors.forename: M
authors.initials: M
authors.lastname: Jiménez-Reyes
authors.forename: M
authors.initials: M
authors.lastname: Solache-Ríos
mesh_terms: D000327:Adsorption; D017886:Durapatite / Q000737:chemistry*; D005459:Fluorides / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008962:Models, Theoretical; D012996:Solutions; D013816:Thermodynamics; D014867:Water; D014961:X-Ray Diffraction
chemical_list: D012996:Solutions; D014867:Water; D017886:Durapatite; D005459:Fluorides