title: Adsorption isotherm studies of chromium (VI) from aqueous solutions using sol-gel hydrotalcite-like compounds.
abstract: In under-developed countries, industries such as paint and pigment manufacturing, leather tanning, chrome plating and textile processing, usually discharge effluents containing Cr(VI) and Cr(III) into municipal sanitary sewers. It has been reported that Cr(VI) acts as a powerful epithelial irritant and as a human carcinogen. In the present work, hydrotalcite-like compounds with a Mg/Al ratio=2 were synthesized by the sol-gel method. The hydrotalcite-like compounds and their corresponding thermally treated products were characterized by powder X-ray diffraction, infrared spectroscopy and N(2) adsorption. The hydrotalcite-like compounds and the heated solids were used as adsorbents for Cr(VI) in aqueous solutions. Adsorption isotherm studies of Cr(VI) from aqueous solution are described. The adsorbent capacity was determined using the Langmuir, Freundlich and Dubinin-Radushkevich adsorption isotherm models. The Cr(VI) adsorption isotherm data fit best to the Langmuir isotherm model. The maximum Cr(VI) uptake by hydrotalcite and the heated solids was determined using the Langmuir equation and was found to range between 26 and 29 mg Cr(VI)/g adsorbent.
authors.affiliation: Centro de Investigaciones en Química Inorgánica de la Universidad de Guanajuato, CP 36050 Guanajuato, Gto, Mexico. ramosre@quijote.ugto.mx
authors.forename: Esthela
authors.initials: E
authors.lastname: Ramos-Ramírez
authors.forename: Norma L Gutiérrez
authors.initials: NL
authors.lastname: Ortega
authors.forename: Cesar A Contreras
authors.initials: CA
authors.lastname: Soto
authors.forename: Maria T Olguín
authors.initials: MT
authors.lastname: Gutiérrez
mesh_terms: D000327:Adsorption; D000536:Aluminum Hydroxide / Q000737:chemistry*; D002857:Chromium / Q000737:chemistry / Q000302:isolation & purification*; D007220:Industrial Waste; D008276:Magnesium Hydroxide / Q000737:chemistry*; D044367:Phase Transition; D012996:Solutions; D013816:Thermodynamics
chemical_list: D007220:Industrial Waste; D012996:Solutions; D002857:Chromium; C010467:hydrotalcite; C074702:chromium hexavalent ion; D000536:Aluminum Hydroxide; D008276:Magnesium Hydroxide