André Lazarin Gallina

A corrosão do aço inoxidável austenítico 304 em biodiesel

Fuel distribution uses 304 stainless steel containers for the storage of biofuels, however, there are few reports in the literature about the corrosive aspects this steel in biodiesel. The objective of this research is to study the corrosive behavior of 304 austenitic stainless steel in the presence of biodiesel, unwashed and washed, with aqueous solutions of citric, oxalic, acetic and ascorbic acids 0,01 mol L-1, and compare with results obtained for the copper (ASTM D130). The employedtechniques were: atomic absorption spectrometry (AAS) and optical microscopy (OM). The results of EAA showed a low rate of corrosion for the stainless steel, the alloys elements studied were Cr, Ni and Fe, the highest rate was observed for the chrome, 1.78 ppm / day in biodiesel with or without washing. The OM of the 304 steel, when compared with that of copper, has a low corrosion rate in the 304 steel/biodiesel system. Not with standing, this demonstrates that not only the 304 steel, but also the copper, corrodes in biodiesel.

Electrochemical behavior of indole for AISI 430 stainless steel in changing the media from 1 mol L-1 H2SO4 to 1 mol L-1 HCl

The adsorption of organic substances in metals and in different media has been attributed to different effects, such as the carbon chain size, type or number of heteroatom in the molecule structure, reactivity, the steric effect, among others. The objective of this work is to study the electrochemical indole behavior for AISI 430 stainless steel (SS), when changing the study media from H2SO4 1 mol L-1 to HCl 1 mol L-1. The experimental techniques used are as follows: the open-circuit potential, anodic and cathodic potentiodinamic polarization, electrochemical impedance spectroscopy, optical microscopy and scanning electron microscopy. These results suggest that the adsorption of indole in the presence of SO4-2 is lower than in the medium containing Cl-, which is justified by the indole action as a weak acid, because it has only a single pair of electrons, which is displaced and takes part in the π-electron aromatic system; thus the first step of the indole reaction in acid media is the protonation and generation of an indole cation.

Estudo da Produção de Álcool Utilizando como Matéria-Prima a Cyperus esculentus (Tiririca)

Os problemas ambientais causados pelo uso de combustiveis fosseis e a necessidade de um novo caminho baseado em fontes energeticas renovaveis impulsionam o desenvolvimento de combustiveis produzidos a partir da biomassa. Os biocombustiveis sao considerados uma opcao estrategica para a geracao de energia, entre eles destaca-se o etanol. Visando minimizar a competicao com a cadeia alimentar, as fontes amilaceas sao alternativas para obtencao do biocombustivel, entre elas a Cyperus esculentus (CE). Este trabalho teve como objetivo estudar as condicoes ideias para a obtencao de etanol a partir da fermentacao da farinha de CE, utilizando a rota enzimatica para a reacao de hidrolise. Foi utilizado planejamento fatorial (3²), a fim de verificar a influencia das variaveis independentes: tempo de fermentacao (h) e concentracao de levedura (g L -1 ) para a rota enzimatica em relacao a resposta grau alcoolico (°GL). Para caracterizacao da materia-prima foram realizados ensaios de determinacao de teor de umidade, teor de amido, acucares redutores (AR), analise quimica elementar e microscopia eletronica de varredura (MEV). Apos a fermentacao, foram realizadas medidas de UV-vis para determinacao do °GL. As amostras apresentaram valores de teor de umidade de 55,05%, teor de amido de 52,38% e de AR de 12,23%. As imagens de MEV mostraram elementos de protoxilema e protofloema. Com o planejamento fatorial alcancou-se as condicoes ideais ( 15 g L -1 para concentracao de levedura e 30 h para o tempo de fermentacao) para obtencao de etanol com teor alcoolico de 24,27 °GL.

PRODUÇÃO DE ETANOL A PARTIR DA FERMENTAÇÃO DE RESÍDUOS INDUSTRIAIS

O etanol e um biocombustivel produzido a partir de diversas materias primas, sendo a principal a cana-de-acucar, tambem podem ser utilizados residuos industriais como o glicerol do biodiesel, e residuos da industria de papel. Esses residuos industriais apresentam em sua composicao consideravel concentracao de carbono, podendo ser utilizados em processos de fermentacao. Com isso, o presente trabalho tem como objetivo produzir etanol pela fermentacao anaerobica do glicerol e de residuos da industria de papel utilizando-se um microorganismo especifico. Foi utilizado um planejamento experimental multivariado 2² com ponto central. O processo de fermentacao foi realizado por 72 horas a 36 °C ± 0,5. Os resultados mostraram uma tendencia de maior producao de etanol nos ensaios com 2 g de residuo celulosico e 4 mL de microorganismo. Os maiores teores de etanol obtido foram de 83 e 81 °GL.

Electrochemical Study of Ceramics Based on Niobium Oxide over Aluminum Alloy AA 3003

Corrosion is an undesirable action which can occur in metals. To minimize this problem, there are several types of coat to the metal surface being researched in an attempt to retard the oxidation processes. In this work, the deposition of a new ceramic coating based on niobium oxide over aluminum alloy AA 3003 was studied in order to obtaining a corrosion resistant and less polluting film. It was utilized the experimental planning to optimize the deposition of ceramics, and it was performed electrochemical tests, scanning electron microscopy and dispersive energy spectroscopy to evaluate these films. The ceramic coating based on niobium oxide obtained presented itself as an effective corrosion inhibitor for aluminum alloy AA 3003.

Corrosion characterization of phosphated carbon steel treated with benzotriazole

Purpose – The purpose of the paper is to show the corrosion effect of benzotriazole in comparison with iron phosphate (PFe) coating as a sealer for the PFe layer in carbon steel paint pre-treatment and to show its ecological advantages as a more environment-friendly inhibiting compound than PFe. Design/methodology/approach – Samples of carbon steel (SAE 1010) were phosphated in two baths, one containing iron PFe and PFe and BTAH (PFe + BTAH). Anodic potentiostatic polarization curves and electrochemical impedance spectroscopy were used to evaluate the corrosion resistance of phosphated carbon steel in 0.1 molL−1 H2SO4, 0.5 molL−1 NaCl and 0.1 molL−1 NaOH. The phosphate layers obtained were analyzed by infrared spectroscopy. Surface observation by scanning electron microscopy (SEM) showed that the PFe and PFe + BTAH layers are deposited as crystals with granular morphology. The electrochemical results showed that the PFe + BTAH coating was more effective in corrosion protection of the carbon steel. Finding...

PRODUÇÃO DE HIDROGÊNIO A PARTIR DO ÁCIDO FÓRMICO UTILIZANDO ELETRODOS DE PLATINA, COBRE E LATÃO.

A preocupacao mundial com a emissao de dioxido de carbono a atmosfera terrestre tem levado a exigencias ambientais mais severas, e provocado o aumentado de estudos de geracao de energias renovaveis e menos poluentes, como por exemplo, o gas hidrogenio. Este trabalho tem como objetivo estudar a producao do gas hidrogenio via eletrolise da solucao aquosa de acido formico 3 mol L -1 , utilizando como eletrodos a platina, latao e cobre. As tecnicas empregadas neste trabalho foram potencial de circuito aberto, polarizacao potenciodinâmica catodica e microscopia optica. Os resultados obtidos mostram que os corpos de prova de latao lixados com lixas de SiC #320 apresentaram os maiores valores de densidade de corrente catodica, consequentemente maior producao de gas hidrogenio.

Optimization of Aluminum Anodizing and Coloring Process Employing Organic Pigment

The process of aluminum anodizing forms an oxide layer constituted of nanotubes where it is possible to insert compounds, amongst these are the pigments and dyes. This study has as its main aim to study the behavior of aluminum alloy 6000, anodized and dyed with monolite red in Na2SO4 0.5 mol L-1 and pH = 4. The techniques employed were: anodic potentiostatic polarization, open circuit potential, chemometry, polarization resistance and optical micrograph. The factorial planning was proposed using four variables (anodizing time, current density, electrolyte concentration, and dye), the response to the planning was the charge transfer resistance. Polarization curves revealed that the anodized and dyed aluminum samples are much more resistant than the non-anodized aluminum. Optical microscopy analyses demonstrated that the dissolution of dye occurs in the solution, but not enough to break the film. As the main result, efficient coloring of aluminum parts was verified with reduction in costs in relation to the energy employed in the process, associated to reduction in time spent for the anodizing process, which makes it suitable to increase industrial production of dyed aluminum parts.

Development and Characterization of an Alternative Process: Nanoceramic Application to the Treatment of Carbon Steel

Paint durability is directly linked to the efficiency of the substrate pre-treatment system. The objective to treat the carbon steel surface prior to painting is to turn the unstable metal surface into a stable surface one, an inert base to receive the paint. This is the main function of the phosphatization processes, which enables good paint adherence and prevents the development of corrosion processes. The demand for cleaner technologies, with lower residue generation, makes the phosphatization an unappealing method, and in this context the use of nanoceramics is an alternative to phosphate conversion layers. The objective of this study is to form a protection film which employs an organic molecule together with the zircon oxide, forming a layer which is able to anchor paint and increase the carbon steel resistance to corrosion. The treatment process conditions were established through the factorial planning, and the samples evaluated through the electrochemical impedance spectroscopy, scanning electronic microscopy and energy dispersive analysis. After comparing results of the electrochemical evaluation of the coating proposed with the iron and zinc phosphate coatings, it was possible to see that the film formed presented better corrosion resistance properties.

Aplicação de SAM em liga de alumínio AA 2024-T3 com desengraxe alcalino

Self-assembly molecules (SAM - Self Assembly Monolayer) are corrosion inhibitors, due to their capacity to organize on surfaces, forming thin films. SAM presents a high affinity to aluminum oxide. However, the interactions between the oxide layer and SAM are not always satisfactory; therefore the oxide formed on the surface presents heterogeneities that hinder SAM film formation. The aim of this work was to study the corrosion protection of aluminum AA 2024-T3 associated with SAM, after treatment with alkaline degreasing. The electrochemical characterization was carried out by electrochemical impedance spectroscopy and anodic potentiodynamic polarization in Na 2 SO 4 0,5 mol.L -1 in pH 4,0. The superficial morphology was investi gated by optic microscopy. The results showed that SAM promoted greater aluminum protection when this was pretreated with degreasing.