Navegando por Autor "VALENTIM, Taynara Lima"

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Acesso aberto (Open Access)
Comportamento do arsênio em perfis de solos do Sítio Ilha de Terra de Caxiuanã-Pará
(2009-06) LEMOS, Vanda Porpino; COSTA, Marcondes Lima da; GURJÃO, Robson da Silva; KERN, Dirse Clara; MESCOUTO, Cleide Samara Tavares; LIMA, Wivian Thaís dos Santos de; VALENTIM, Taynara Lima
Arsenic concentrations in soil profiles with archaeological black earth (ABE) and surroundings (SA) from the Sítio Ilha de Terra, Caxiuanã, in the State of Pará, Amazon region, may provide information on anthropogenic activity in the Amazonian habitat. The samples of ABE and SA soil profiles were submitted to chemical and mineralogical analysis. The obtained data show that Fe and As concentrations increase with depth while organic matter (OM) decreases. The highest concentrations of Fe and As are observed in the SA profile. These results indicate interactions between Fe and As and suggest that OM promotes the dissolution of goethite and leaching of Fe and As in the ABE profile.
Acesso aberto (Open Access)
Especiação e quimissorção de Pb(II) em rejeito de caulim
(2013) PINHEIRO, Marta Helena Tavares; LEMOS, Vanda Porpino; DANTAS, Kelly das Graças Fernandes; VALENTIM, Taynara Lima
This study assesses the adsorption of Pb(II) on natural kaolin waste (KRnatural) and on that treated with 3 mol L-1 H2SO4 and HCl. Equilibrium and thermodynamic parameters were determined. The results indicate that the values of CEC, specific area and SiO2/Al2O3 ratio (4.6-6.0 cmol kg-1, 14.0-16.0 m² g-1 and 1.16-1.30, respectively) vary only slightly for the adsorbents; the concentration of Pb2+ is much higher than that of other species (PbOH+ and Pb(OH) 2). The values of RL, ΔGº, ΔHº and ΔSº are typical of feasible, spontaneous, exothermic and ordered adsorption. The chemisorption on KR natural is more feasible and ordered.