Navegando por Autor "SENA, Rafael dos Santos Fernandes"

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Acesso aberto (Open Access)
Adsorção de cromo (VI) por carvão ativado granular de soluções diluídas utilizando um sistema batelada sob pH controlado
(Instituto Nacional de Pesquisas da Amazônia, 2009-09) SOUZA, Renata dos Santos; CARVALHO, Samira Maria Leão de; GARCIA JÚNIOR, Márcio Ronald de Lima; SENA, Rafael dos Santos Fernandes
In Amazonia, chromium is mainly used in the leather and wood industries. It is responsible for many health problems, because of its toxicity. These industries remove chromium waste by various processes, such as adsorption. This work shows the results of Cr(VI) adsorption by commercial granular activated carbon (GAC) as adsorbent from diluted solutions, and batch systems with controlled pH. The functional groups on the CAG surface was carried out by the Boehm method. In addition, effect of pH on the Cr(VI) adsorption, adsorption equilibrium, and kinetic were studied under experimental conditions (pH = 6, MA = 6g, for 90min.). On the GAC surface, carboxylic groups were found to be in higher concentrations (MAS=0,43 mmol/gCAG), which increase the Cr(VI) adsorption, principally in acidic pH values. The adsorption capacity is dependent on the pH of the solution, due to its influence on the surface properties of the CAG and different ionic forms of the Cr(VI) solutions. The adsorption equilibrium data was adjusted satisfactorily by the Langmuir isotherm (R2=0,988), favorable type. From kinetics adsorption of 20 mg/L and 5 mg/L, the results were compatible with the national legislation (Res. nº 357/05). Therefore, the experimental system using (CAG) was efficient in removing the Cr(VI) from liquid streams containing low concentrations of the metal.
Acesso aberto (Open Access)
Estudo da síntese de zeólitas tipo A, X e sodalita empregando reatores vítreos: análise dos métodos dinâmico e estático de síntese a partir de caulim residual da Região Amazônica
(Universidade Federal do Pará, 2013-12-26) SENA, Rafael dos Santos Fernandes; MARTELLI, Marlice Cruz; http://lattes.cnpq.br/1213009262936026
Kaolin processing companies generate kaolinitic residue that is stored in sedimentation ponds, occupying large physical areas. The utilization of these wastes is an important factor in the economic and the environmental terms. Here a study of the synthesis of A, X and sodalite zeolites using as raw material a kaolin waste from the Amazon Region is presented. The waste was pretreated for removal of the organic matter, comminuted and thermally activated at 750 °C for 2 hours. After selecting the optimum particle size for the synthesis by the pré-zeolitização step, two methods were tested to obtain the zeolites: dynamic and static. For the reaction mixture of the synthesis, were worked with the ratios SiO2/Al2O3 of 2/1 and 3/1 to obtain zeolites. Analyses of X-Ray Diffraction (XRD), X-Ray Fluorescence Spectroscopy (XRF) and Scanning Electron Microscopy (SEM) analyzes showed good phase formation for the NaA zeolite to the ratio 2/1, in the both sinthesys methods, dynamic and static, and without aging, and good phase formation for the NaX zeolite to the ratio 3/1, using static synthesis and with 12 hours aging. The sodalite phase was formed in the same stoichiometry of the NaX zeolite, but using static synthesis and without aging.