title: Faster extraction of heavy metals from soils using vacuum and ultrasonic energy.
abstract: A fast vacuum- and ultrasound-assisted acid extraction of Co, Cu, Fe, Mn, Pb, and Zn from soils using a homemade system has been investigated. Preliminarily, a full factorial design with two levels and three variables (extracting agent, extraction temperature, and sonication time) was applied to optimize the extraction conditions (without vacuum) for some heavy metals (Cu, Mn, Pb, and Zn). The best results were obtained with a 3:1 HCI extraction solution, temperature of 80 degrees C, and time of 2 h. As this sonication time was too long, a vacuum pump was used to produce air bubbles in order to increase the contact between the sample and the extracting agent and to prevent the sample sedimentation. This improvement drastically reduced the sonication time to 2 min. Under these conditions, Co, Cu, Mn, and Zn were totally extracted (recoveries of 86-99%), while recoveries of 73-76 and 74% were obtained for Fe and Pb, respectively. The LOD values using flame atomic absorption spectrometry for determination of Co, Cu, Fe, Mn, Pb, and Zn were 3.2, 7.5, 37.5, 7.5, 22.5, and 3.8 micro glg, respectively. The RSDs were lower than 11% (n = 3).
authors.affiliation: Centro de Tecnologia Mineral-CETEM, Coordenação de Análises Minerais, Av. Pedro Calmon 900, Cidade Universitária, CEP 21941-908, Rio de Janeiro, Brazil.
authors.forename: Fernanda V M
authors.initials: FV
authors.lastname: Pontes
authors.forename: Manuel C
authors.initials: MC
authors.lastname: Carneiro
authors.forename: Evelyn M F
authors.initials: EM
authors.lastname: de da Souza
authors.forename: Lílian I D
authors.initials: LI
authors.lastname: da Silva
authors.forename: Maria Inês C
authors.initials: MI
authors.lastname: Monteiro
authors.forename: Arnaldo A
authors.initials: AA
authors.lastname: Neto
mesh_terms: D057230:Limit of Detection; D019216:Metals, Heavy / Q000302:isolation & purification*; D012987:Soil / Q000737:chemistry*; D013054:Spectrophotometry, Atomic / Q000379:methods; D014465:Ultrasonics / Q000379:methods*; D014618:Vacuum
chemical_list: D019216:Metals, Heavy; D012987:Soil