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Determinação da cinética de cristalização em diferentes escalas visando o projeto de cristalizador em batelada utilizando o sistema monopentaeritritol-água como modelo
(Universidade Federal de São Carlos, 2007-05-04) Bernardo, André; Giulietti, Marco; https://lattes.cnpq.br/7703659740618915; https://lattes.cnpq.br/5705402824877708
Previous studies on crystallization as an industrial process have been frequently limited to just one aspect of the process. They usually study parameter optimization or a method for monitoring solution or suspension, frequently not taking into account the several aspects that compose the quality of crystalline product, or the fact that the studied process is such more important when can be applied in industry. From this point of view, this study proposes to go forward to the evaluation of feasibility of industrial application of its own results. Initially, it was determined the solubility of the model-system monopentaerythritol in water to infer from this result some thermodynamic parameters, specific heat and heat of crystallization, which are necessary to a possible crystallizer design. Afterwards, it was done the optimization of the crystallization parameters in seeded cooling batch of the model-system, by monitoring suspension tubidity, and refractive index of solution and chord length distribution of the crystals, in three different scales: 0,35 L in reactor of 0,6 L, 1,05 L in reactor of 2L, and 6,2 L in reactor of 9L. In-line monitoring of system properties, as well as the measurement of crystal size distribution and measurements of optical microscopy of seeds and final product, allowed the optimization of kinetic parameters, considering the existence of agglomeration in two of the three studied scales. With the obtained kinetic parameters, the extrapolation of them to other scales was tried. This scale up was not possible, but it was utilized the kinetic parameters obtained in the 9 L reactor to design a crystallization system, considering two crystallizers: one larger of 40 m³ suitable to product an intermediate chemical as pentaerythritol, and a smaller one of 2 m³ considering the system as a specialty chemical. The simulations carried out, utilized in the design of the crystallizers, allowed to verify that there is limitation in heat exchange of the larger designed crystallizer which hinders the imposition of non-linear cooling profiles, normally indicated in scientific papers as adequate solution to improve the performance of produced crystals. This limitation does not exist in the smaller designed crystallizer, which allows imposing non-linear cooling profiles and maximizing the performance of crystalline product, by obtaining larger crystals with narrow size distribution.
Composição e distribuição de coleoptera aquáticos (insecta) em córregos de baixa ordem no Estado de São Paulo, Brasil
(Universidade Federal de São Carlos, 2007-05-04) Segura, Melissa Ottoboni; Gessner, Alaíde Aparecida Fonseca; https://lattes.cnpq.br/8465752836529703; https://lattes.cnpq.br/5081348804259676
The beetles are an important part of the insect fauna of most aquatic ecosystems. However, with the exception of the Elmidae, they have not been used extensively for water quality evaluation. This is due in large part to the fact that most water beetle adults and larvae, with the exception of the elmids, some adult Dryopidae and larvae Psephenidae, are air-breather and do not depend on dissolved oxygen in water for respiration. However, many beetles appear to live and reproduce in restricted aquatic habitats, thus can colonize the smallest water bodies, and the loss of those habitats may mean a loss of those species. And, if a high diversity of species is indicative of good water quality, then the high diversity of beetles in an aquatic environment is certain important. The main goals of this study were to evaluate and to compare the impact on the beetle fauna from small streams in reference (Conservation Areas), sugar-cane agriculture and Eucalyptus plantations and pasture areas. The main question addresses here was: which are the main consequences for diversity and abundance of beetles with deforestation of riparian vegetation. In this study were visited six Conservation Areas where 20 streams were sampled and three landscape impacted areas by sugar-cane agriculture and Eucalyptus plantations and pasture, where 14 streams were studied. The results showed a high diversity of Coleoptera have been identified 49 genera, of which 44 genera were collected in reference areas and only 17 genera were registered in impacted areas. The family Elmidae comprised 83.47% of the 1506 specimens from conservation areas. However in the impacted areas the family Hydrophilidae was more abundant, it represented 34.8% of the 87 specimens collected in these locations. The results of physics an chemistry of the water variables did not show much differences between both situations (Conservation and impacted areas), however the deforestation of the riparian vegetation was a determinant factor in the alteration of the composition, diversity and abundance of beetles in the studied streams.