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Zinc is a heavy metal that enters the environment as consequence of both natural and anthropogenic activities. The association of the soil geochemical fractions and adsorption kinetics were studied to evaluate the behavior of the Zn in a contaminated Utisol soil. The contaminated soil samples were collected at depth 0-20, 20-40, 40-60, and 60-80cm into the Manaus Industrial District (MID) region. The study was performed in soil fractions at 50μm being the samples submitted to sequential extraction, batch experiments, X-ray diffraction (XRD) and Fourier transformed infrared spectroscopy (FT-IR). The adsorption kinetics was fitted according to Lagergren equation. The physical and chemical proprieties of soil showed that organic matter has low cation adsorption capacity and the existence of kaolinite poorly ordered, monoclinic and mixed with others mineral. The kinetics experiments performed indicated that the Zn is adsorbed by sorption process most probably with the formation of two bidentate surfaces. The Zn contents are above established by CETESB (reference value 60mg kg-1) being observed remarkable differences between exchangeable and residual fraction. Source

Oliveira P.A.S.,Institute Ciencias Exatas ICE | Sartori L.M.,Centro Tecnico Cientifico CTC | Rey N.A.,Centro Tecnico Cientifico CTC | Dos Santos H.F.,Institute Ciencias Exatas ICE | And 2 more authors.
Journal of the Brazilian Chemical Society | Year: 2013

Research in Medicinal Chemistry has involved numerous aspects focusing on the treatment of several kinds of diseases, such as cancer, especially by the combination of therapeutic potentials by using different molecules. With this aim, a computational study combining pyrazinamide (PZA), an indispensable tuberculostatic drug, and cisplatin, an important antitumoral agent, was conducted to combine the best features of both compounds. A search for the most stable structure of the platinum(II)-PZA complex at a 2:1 stoichiometry: diclorodi(pyrazinamido)platinum(II), or cis-[PtCl2(PZA)2], was performed, using functional theory (DFT) associated to a mixed-level factorial design of two factors type 5 × 3, totaling 15 experiments. After evaluating the response surface and following the performance of seven experiments to validate the area identified as optimal, the most stable structure is that in which the dihedral 2Cl/1Pt/5O/7C is at an 18.9° angle. © 2013 Sociedade Brasileira de Química. Source

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