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Background. Coffee samples adulterated with roasted corn and roasted soybean were analyzed using a voltammetric electronic tongue equipped with a polypyrrole sensor array. Materials and methods. Coffee samples were adulterated in concentrations of 2%, 5%, 10% and 20% of roasted corn and roasted soybean; 5 replicates of each were used. The discrimination capacity of a voltammetric electronic tongue elaborated with a polypyrrole sensor array, was evaluated by principal component analysis and cluster analysis, while the capacity to perform quantitative determinations was carried out by partial least squares. Results. The results obtained by the application of principal component analysis showed an excellent ability to discriminate adulterated samples. Additionally, the classifications obtained by cluster analysis was concordant with those obtained by principal component analysis. On the other hand, the evaluation of the ability to quantitatively analyze the adulterated samples showed that the polypyrrole sensor array provides sufficient information to allow quantitative determinations by partial least squares regression. Conclusion. It could be concluded that the voltammetric electronic tongue used in this work allows the sufficient analysis of coffee samples adulterated with roasted corn and roasted soybean.

ResumenEl objetivo de este estudio fue realizar el análisis exergético de la gasificación de biomasa residual con la finalidad de obtener energía útil. Se desarrolló un modelo para la gasificación de biomasa basado en el equilibrio químico de las reacciones. Este modelo permite predecir la evolución de la composición del gas de síntesis en función de la temperatura, las presiones y la composición elemental de los residuos del proceso de extracción de aceite de palma y orujo de lavado de uva (hidrogeno, oxigeno, carbono y nitrógeno), como también hacer un análisis exergético. Se encontró que independiente del agente gasificante, la concentración de monóxido de carbono e hidrógeno tienden a incrementar significativamente a altas presiones y elevadas temperaturas. Además, se muestra que la eficiencia exergética incrementa con la temperatura y disminuye con el aumento de la relación aire/combustible. Palabras clave: biomasa, gasificación, equilibrio químico, exergía Exergy Analysis of Biomass Gasification AbstractThis paper shows the exergy analysis applied to the gasification process of residual biomass with the purpose of obtaining useful energy. A model for the biomass gasification based on chemical equilibrium of the reactions is proposed. The model allows predicting the syngas composition as a function of temperature, pressure and ultimate analysis of palm oil and grapevine pruning waste (determining hydrogen, oxygen, carbon and nitrogen). It was found that the carbon monoxide and hydrogen concentration significantly increase at high pressure and temperature independently of the gasifying agent. Furthermore, it was also noticed that the exergy efficiency increases as temperature increases, and decreases as the relative fuel/air ratio increases.

Biomass gasification process is simulated in order to determine the influence of the operating parameters on the quality of the gas produced. Furthermore, the hydrogen required to enrich the syngas is also established. The modeling and simulation showed that the gas obtained by gasification at atmospheric pressure is mainly composed of H2 and CO; however, the molar ratio H2/CO is not favorable for synthesizing fuels such as methanol. This shows the need to enrich the syngas with additional hydrogen. For the case study developed, for each 100 kg / hr of biomass waste gasified, the amount of additional hydrogen required ranges between 2 to 6 kg / hr in order to obtain a molar ratio H2/CO close to 2. Using palm fiber, the amount of hydrogen required would be 4 kg / hr. This additional hydrogen could be derived from solar energy using thermoelectric modules with an effective area of solar radiation close to 400 m2 per kg of biomass. The simulation was performed using ASPEN PLUS®.

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