Operating parameters on biological nitrogen removal of water by simultaneous nitrification and denitrification

O nitrogênio é um dos contaminantes mais importantes presentes nas águas residuais. As alternativas tecnológicas mais usuais para o tratamento de águas contendo esse composto lançam mão do ciclo bioquímico do nitrogênio, o qual se sustenta em dois processos, a nitrificação e a desnitrificação. Dentre os parâmetros que influenciam na remoção de nitrogênio, podemos citar a concentração de oxigênio dissolvido, relação carbono/nitrogênio, temperatura, pH entre outros. Este trabalho apresenta uma revisão sobre a remoção biológica de nitrogênio das águas e os principais parâmetros que influenciam na sua remoção, dando ênfase ao processo de nitrificação e desnitrificação simultânea.Nitrogen is one of the most important contaminants present in wastewater. The most common alternative technologies for the treatment of waters containing this compound lay hold of the biochemical cycle of nitrogen, which is based on two processes, nitrification and denitrification. Among the parameters that influence the removal of nitrogen, we can mention the concentration of dissolved oxygen, carbon/nitrogen ratio, temperature, pH, and other relationships. This paper presents an overview of the biological nitrogen removal of water and the main parameters that influence the removal, emphasizing the simultaneous nitrification and denitrification process.Fil: Miranda Zoppas, Fernanda. Universidade Federal do Rio Grande do Sul; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Bernardes, Andrea Moura. Universidade Federal do Rio Grande do Sul; BrasilFil: Meneguzzi, Álvaro. Universidade Federal do Rio Grande do Sul; Brasi

Passivation of Carbon Steel Using Intelligent Epoxy Paint

This paper presents the production of an epoxy paint associated with a determined concentration of PAni emeraldine base binder, in order to increase dispersion of PAni polymer chains in the paint allow physical contact between PAni chains, the electrolytic medium, and the metal of interest. The coating called Intelligent Epoxy Paint (IEP) seeks to potentialize the electrolytic capacity of PAni to produce passivation, differentiated research which uses PAni in oxidized and conductive form as paint pigment that needs high PAni concentrations. The physicochemical characterization and morphological presented results that indicate the preservation of the desirable properties of PAni in order to make the passivation process possible. The electrochemical tests showed the passivation and/or maintenance of the passivation of the metal of interest, without the need to apply an external current

Filament wound resin composites Preparation and elastic properties

SIGLEAvailable from British Library Document Supply Centre- DSC:D72413/87 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Filme autosuportado de polianilina desdopada para aplicações anticorrosivas Characterization of self-standing films of undoped polyanilina

Os polímeros intrinsecamente condutores (PIC), como a polianilina (PAni), têm sido estudados com alternativa em filmes protetores de metais oxidáveis contra a corrosão. Dada a dificuldade de fusão ou dissolução da PAni para a produção de filmes, investigou-se a possibilidade de obter filmes pela mistura de PAni no estado oxidado e desdopado, conhecida como base esmeraldina, com plastificante não dopante 4-cloro-3-metilfenol (CMF) e solvente conveniente. Filmes produzidos desta forma foram caracterizados por espectroscopia FTIR e RAMAN, por TGA e ensaio de voltametria cíclica. A caracterização mostrou filmes termicamente estáveis até a temperatura de 200 ºC com indícios de interação da PAni com o CMF, com a PAni se mantendo no estado oxidado no filme produzido, condição necessária para futura aplicação como filme anticorrosivo de proteção anódica.<br>The intrinsically conductive polymers (PCI), such as polyaniline (PAni), have been studied as an alternative in the development of protective films of oxidizable metals against corrosion. Given the difficulty of mixing and dissolving PAni for the production of films, here we investigated the possibility of obtaining a mixture of PAni films in the oxidized, undoped state, referred to as emeraldine base, with the non-doping plasticizer 4-chloro-3-methylphenol (CMF) and a convenient solvent. Films produced in this way were characterized by FTIR and Raman spectroscopy, TGA and cyclic voltammetry. The characterization showed films thermally stable up to 200 ºC with evidence of interaction between PAni and CMF, with PAni remaining in the oxidized state in the film produced, which a necessary condition for application as anodic protection in anticorrosion films

Water absorbed by polyaniline emeraldine tends to organize, forming nanodrops

Interactions, in terms of both binding energies and microscopic organization, of water molecules absorbed by hydrophilic polyaniline emeraldine base have been investigated using quantum mechanical calculations, molecular dynamics simulation, FTIR spectroscopy, and 1H NMR. From an enthalpic point of view, water molecules interact more favorably with imine nitrogen atoms than with amine ones, even though the latter are entropically favored with respect to the former because of their two binding sites. Quantum mechanical results show that interaction energies of water molecules reversibly absorbed but organized individually around a binding site range from 3.0 to 6.3 kcal/mol, which is in good agreement with activation energies of 3–5 kcal/mol previously determined by thermodynamic measurements. The irreversible absorption of water to produce C–OH groups in rings of diimine units has been examined considering a three steps process in which water molecules act as both acidic and nucleophilic reagent. Although calculations predict that the whole process is disfavored by 5–8 kcal/mol only, FTIR and 1H NMR detected the existence of reversibly absorbed water but not of C–OH groups. Both the binding energies and the structural information provided by molecular dynamics simulations have been used to interpret the existence of two types of physisorbed water molecules: (i) those that interact individually with polymer chains and (ii) those immersed in nanodrops that are contained within the polymeric matrix. The binding energies calculated for these two types of water molecules are fully consistent with the thermodynamic activation energies previously reported