title: Fluoride removal in water by a hybrid adsorbent lanthanum-carbon.
abstract: Various health problems associated with drinking water containing high fluoride levels, have motivated researchers to develop more efficient adsorbents to remove fluoride from water for beneficial concentrations to human health. The objective of this research was to anchor lanthanum oxyhydroxides on a commercial granular activated carbon (GAC) to remove fluoride from water considering the effect of the solution pH, and the presence of co-existing anions and organic matter. The activated carbon was modified with lanthanum oxyhydroxides by impregnation. SEM and XRD were performed in order to determine the crystal structure and morphology of the La(III) particles anchored on the GAC surface. FT-IR and pK(a)'s distribution were determined in order to elucidate both the possible mechanism of the lanthanum anchorage on the activated carbon surface and the fluoride adsorption mechanism on the modified material. The results showed that lanthanum ions prefer binding to carboxyl and phenolic groups on the activated carbon surface. Potentiometric titrations revealed that the modified carbon (GAC-La) possesses positive charge at a pH lower than 9. The adsorption capacity of the modified GAC increased five times in contrast to an unmodified GAC adsorption capacity at an initial F(-) concentration of 20 mg L(-1). Moreover, the presence of co-existing anions had no effect on the fluoride adsorption capacity at concentrations below 30 mg L(-1), that indicated high F(-) affinity by the modified adsorbent material (GAG-La).
authors.affiliation: División de Ciencias Ambientales, Instituto Potosino de Investigación Científica y Tecnológica, A.C., Camino a la Presa San José 2055, Col. Lomas 4(a) sección, C.P. 78216 San Luis Potosí, S.L.P., Mexico.
authors.forename: Esmeralda
authors.initials: E
authors.lastname: Vences-Alvarez
authors.affiliation: División de Ciencias Ambientales, Instituto Potosino de Investigación Científica y Tecnológica, A.C., Camino a la Presa San José 2055, Col. Lomas 4(a) sección, C.P. 78216 San Luis Potosí, S.L.P., Mexico.
authors.forename: Litza Halla
authors.initials: LH
authors.lastname: Velazquez-Jimenez
authors.affiliation: División de Ciencias Ambientales, Instituto Potosino de Investigación Científica y Tecnológica, A.C., Camino a la Presa San José 2055, Col. Lomas 4(a) sección, C.P. 78216 San Luis Potosí, S.L.P., Mexico.
authors.forename: Luis Felipe
authors.initials: LF
authors.lastname: Chazaro-Ruiz
authors.affiliation: Universidad Autónoma de San Luis Potosí, Álvaro Obregón 64, Centro Histórico, C.P. 78000 San Luis Potosí, SLP, Mexico.
authors.forename: Paola E
authors.initials: PE
authors.lastname: Diaz-Flores
authors.affiliation: División de Ciencias Ambientales, Instituto Potosino de Investigación Científica y Tecnológica, A.C., Camino a la Presa San José 2055, Col. Lomas 4(a) sección, C.P. 78216 San Luis Potosí, S.L.P., Mexico.
authors.forename: Jose Rene
authors.initials: JR
authors.lastname: Rangel-Mendez
mesh_terms: D000327:Adsorption; D002244:Carbon / Q000737:chemistry*; D060766:Drinking Water / Q000737:chemistry*; D005459:Fluorides / Q000302:isolation & purification*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007811:Lanthanum / Q000737:chemistry*; D011199:Potentiometry; D055672:Static Electricity; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods*
chemical_list: D060766:Drinking Water; D014874:Water Pollutants, Chemical; D007811:Lanthanum; D002244:Carbon; D005459:Fluorides
keywords: Activated carbon; Adsorption; Fluoride; Lanthanum