The present work describes an experimental investigation concerning the production and characterization of biogas, obtained from biomass of Eichhornia crassipes and biomass of aquatic plants mixture (Eichhornia crassipes; Eichhornia azurea; Pistia stratiotes and Salvinia). The biogas was obtained in anaerobic biodigestion process. The biogas obtained has considerable tenors of methane, in way to make possible its use

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In this article we study the behavior of biodiesel density from soybean oil, sunflower oil, canola oil, and beef tallow, the last one transesterified with ethanol and the others with methanol in relation to temperature with a metrological point of view. These quantities were measured with a digital density meter, one of the Brazilian density standards, in a temperature range between 15 and 40°C. Measurement uncertainty was calculated. The behavior of density is analyzed considering the estimated uncertainty. The density from all the samples investigated shows a linear behavior with respect to temperature.

A oportunidade gerada pela álcali-ativação de escórias granuladas de alto forno abriu perspectiva para ex-ploração desta tecnologia no tocante a outros materiais baseados no sistema SiO2-Al2O3-CaO. Apesar disso, poucos estudos evidenciam os efeitos da álcali-ativação nos cimentos Portland que contém adições de escó-ria ou de pozolana, e que elucidem o que ocorre, em termos de microestrutura e propriedades, se diferentes tipos e teores de álcalis forem utilizados. Este artigo apresenta um trabalho de investigação dos efeitos da álcali-ativação nos tempos de pega e na resistência à compressão de um tipo comercial de cimento Portland composto com escória de alto forno, e na microestrutura desenvolvida. Os resultados revelaram que a pega e o endurecimento podem ser acelerados até o ponto de serem instantâneos, e que resistências à compressão da ordem de 70% da resistência máxima prevista pelo fabricante, aos 28 dias de idade, podem ser alcança-das em menos de 24 horas. Contudo, as análises microestruturais por MEV, DRX e DSC, indicaram que a incorporação dos álcalis interfere significativamente na cinética das reações de hidratação, principalmente na formação do hidróxido de cálcio e das fases AFm e AFt, levando-as à alterações morfológicas e compo-sicionais anômalas, que podem ser instáveis e gerar o comprometimento da resistência mecânica, em idades mais tarde.

The world is looking for changes in its energetic matrix through the use of biofuels to reduce the dependence on oil derivatives. Currently, the number of studies concerning mixtures of triglycerides from animals or plants with diesel fuel has risen due to efforts to reduce the consumption of diesel oil. This paper studies the behavior of the density of plant oils mixed with diesel fuel in relation to temperature, which is essential to guarantee engine efficiency. The density is related to the mass and to the volume being a critical property to the assessment of the subministered energy to the engine by the injection system, which behaves like a pump of positive displacement. Samples of the diesel fuel mixture were made with plant triglycerides in proportion and range of ∼5–20%. The densities of the samples were measured in a density meter with temperature varying between 18 and 25°C, as well as at 15°C, according to ASTM standard. Afterwards, the uncertainties of measurement were calculated, and the density change with respect to temperature is presented and shown in density variation curves. An analysis of the density variation curves shows that.