Dionisio Malagón-Romero

The avocado seed is a major waste generated by the avocado agroindustry in different countries. This waste can be valorized by producing biofuels and other products through a circular economy approach. In this work, the Kissinger–Akahira–Sunose (KAS) and Ozawa-Flynn Wall (OFW) isoconversional methods were used to estimate the activation energy of pyrolysis, which ranged from 24.17 to 226.34 kJ/mol. Additionally, avocado seeds were pyrolyzed in laboratory equipment to generate biochar, gas, and bio-oil. Bio-oil was obtained with a yield of 4% and a maximum caloric value of 21.641 kJ/kg, with a high hydrocarbon content. Biochar (37.5 wt.%) was also obtained, which gained energy and activated carbon. Gas is significant in the pyrolysis process, with 60% productivity. Three cases of pyrolysis processes were simulated, which presented better experimental performance related to biochar and bio-oil yields. These cases were assessed via a sensitivity analysis of the economic component, where the economic margin of both pyrolytic products is positive for any sale price. In the minimum price of biochar, the economic margin was approximately 2%, whereas in the maximum price, the profit was approximately 60%. For the case of bio-oil, the maximum profit was approximately 35%. This research demonstrated the high potential of rapid pyrolysis of avocado seed residues for obtaining bio-oil and biochar fuels with high energy values and promoting a circular economy.

La planificación de la sesión docente, herramienta fundamental para el éxito del proceso educativo, cobra especial relevancia cuando se articula con el diseño curricular. Por tanto, esta ponencia describe esta conexión y ofrece estrategias para una planificación efectiva. El diseño curricular define el marco general del proceso educativo, mientras que la planificación de las actividades en el aula concreta las acciones de enseñanza, aprendizaje que se llevarán a cabo. La coherencia entre ambos niveles es crucial para asegurar que las actividades sean relevantes, significativas y contribuyan al logro de los objetivos de aprendizaje. La ponencia presenta los pasos a seguir para una planificación efectiva como son: Análisis del diseño curricular para comprender en profundidad sus perfiles, objetivos, contenidos, competencias, resultados de aprendizaje y criterios de evaluación; selección de actividades para la elección de las más adecuadas para el logro de los resultados de aprendizaje, considerando las características de los estudiantes y el contexto educativo; diseño de las actividades lo que implica planificar detalladamente la metodología, los recursos y la evaluación; implementación de las actividades para llevarlas a cabo de forma eficaz, adaptándolas a las necesidades e intereses de los estudiantes; y, finalmente, la evaluación de las actividades para medir el aprendizaje y realizar los ajustes necesarios. Estas etapas se aplican a una sesión de un curso de Biotecnología para pregrado en Ingeniería Química mostrando como determinan el syllabus, el desarrollo de los contenidos de la sesión, los instrumentos de evaluación y las rúbricas que los acompañan.

Water hyacinth is classified as a high-risk invasive species but is a source of biomass to obtain bio-oil and biochar by pyrolysis reaction. The Kissinger- Akahira-Sunose model (KAS), Ozawa-Flynn Wall (OFW), and Friedman model, determined the pyrolysis activation energy to be 213.19 kJ mol⁻¹, 222.55 kJ mol⁻¹, and 248.09 kJ mol⁻¹, respectively. Bio-oil was obtained with a 2.2% yield, and a maximum calorific value of 21,641 kJ kg⁻¹. The composition was 44% hydrocarbons, 27% aromatic hydrocarbons, 6% alcohols and phenols, 4% acids, and 19% aldehydes, ketones, ethers, nitriles, and others. A 48.84 wt% biochar was also obtained, gaining energy and active carbon. Bio-oil could be a candidate for the production of refined chemical products.

Objective: To investigate the effect of using mathematical software as a tool to develop problem-solving competence in mechanical engineering students. Methods: A group of 59 students were evaluated using a test consisting of four technological problems related to Bloom´s taxonomy levels of understanding and application. Interpretation and explanation questions were used for the understanding level, and execution and implementation questions were used for the application level. First, the students tried to solve the problems by manual calculations; then, after brief instruction, they tried to solve them by coding using mathematical software. Results: Successful problem solutions increased from 72 to 93%, 15 to 62% and 13 to 26% of the students’ totals in interpreting, explaining, and implementing situations, respectively, but there was a 55 to 44% regression in regard to execution. Better results in understanding questions with respect to applying questions could be due to the increase in difficulty at the taxonomy level. Conclusion: The current study demonstrates the convenience of using computational tools to facilitate the application of mathematical techniques in problem solving and to improve the learning of engineering students. Objetivo: Investigar el efecto del uso de software matemático como herramienta para desarrollar la competencia de resolución de problemas en estudiantes de ingeniería mecánica. Métodos: Se evaluó a un grupo de 59 estudiantes mediante una prueba con cuatro problemas tecnológicos relacionados con los niveles de comprensión y aplicación de la taxonomía de Bloom. Se utilizaron preguntas de interpretación y explicación para el nivel de comprensión y preguntas de ejecución e implementación para el nivel de aplicación. En primer lugar, intentaron resolver los problemas mediante cálculos manuales y, tras una breve instrucción, programando en un software matemático. Resultados: La solución exitosa de problemas aumentó de 72 a 93%, 15 a 62% y 13 a 26% del total de estudiantes en interpretar, explicar e implementar situaciones respectivamente, pero hubo una regresión de 55 a 44% en la ejecución. Los mejores resultados en la comprensión con respecto a la aplicación de preguntas podrían deberse al aumento de la dificultad en el nivel de taxonomía. Conclusión: El estudio demuestra la conveniencia de utilizar herramientas computacionales para facilitar la aplicación de técnicas matemáticas en la resolución de problemas y mejorar el aprendizaje de los estudiantes de ingeniería.

Electric scooters are used as alternative ways of transport because they easily make travel faster. However, the batteries can take around 5 h to charge and have an autonomy of 30 km. With the presence of the hydrogen cell, a hybrid system reduces the charging times and increases the autonomy of the vehicle by using two types of fuel. An increase of up to 80% in maximum distance and of 34% in operating times is obtained with a 1:10 scale prototype with the hydrogen cell; although more energy is withdrawn, the combined fuel efficiency increases, too. This suggests the cell that is used has the same behavior as some official reported vehicles, which have a long range but low power. This allows concluding that use of the cell is functional for load tests and that the comparison factor obtained works as input for real-scale scooter prototypes to compete with the traditional electric scooters.

Waste cooking oil (WCO) is an important feedstock for biofuel production due to its low cost and extensive availability, primarily by transesterification. A more recent approach to take advantage of this feedstock is through pyrolysis. In this study, WCO was collected from a fast food restaurant and then pyrolyzed, employing two different heating rates and four temperatures, at a fixed residence time. The composition of the products was determined by gas chromatography‐mass spectrometry. The best bio‐oil yield was 77.59 %, obtained at 700 °C and 10 °C min⁻¹. The highest contents of octane, nonane, and decane were reached at 400 °C and 15 °C min⁻¹. Therefore, WCO proves to be an important resource for obtaining biofuel or chemical solvents for the industry.

Hydrogen produced by microorganisms is a topic of growing interest because of its potential for derivation from several agro-industrial by-products. In this study, we evaluated the hydrogen production of strains of genus Clostridium (Clostridium acetobutylicum and Clostridium butyricum) using glycerol as a carbon source. Fermentation studies were conducted using three initial concentrations of glycerol: 10, 30 and 50 g/L. The micro-organism growth kinetics and the amounts of solvents and gases were recorded over 48 h. The strain C. acetobutylicum exhibited the best results in terms of hydrogen production, the highest production yield (Y _p/s) of 0.37 mol H₂/mol glycerol and the highest level of productivity (0.75 mg H₂/(L·h)). Based on these results, it is reasonable to conclude that glycerol could be effectively exploited as a carbon source for hydrogen production, which adds value to this primary by-product of standard biodiesel processes.

Hydrogen is expected to play an important role as a clean, reliable and renewable energy source. A key challenge is the production of hydrogen in an economically and environmentally sustainable way on an industrial scale. One promising method of hydrogen production is via biological processes using agricultural resources, where the hydrogen is found to be mixed with other gases, such as carbon dioxide. Thus, to separate hydrogen from the mixture, it is challenging to implement and evaluate a simple, low cost, reliable and efficient separation process. So, the aim of this work was to develop a polymeric membrane for hydrogen separation. The developed membranes were made of polysulfone via phase inversion by a controlled evaporation method with 5 wt % and 10 wt % of polysulfone resulting in thicknesses of 132 and 239 micrometers, respectively. Membrane characterization was performed using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), atomic force microscopy (AFM), and ASTM D882 tensile test. Performance was characterized using a 2 3 factorial experiment using the time lag method, comparing the results with those from gas chromatography (GC). As a result, developed membranes exhibited dense microstructures, low values of RMS roughness, and glass transition temperatures of approximately 191.75 °C and 190.43 °C for the 5 wt % and 10 wt % membranes, respectively. Performance results for the given membranes showed a hydrogen selectivity of 8.20 for an evaluated gas mixture 54% hydrogen and 46% carbon dioxide. According to selectivity achieved, H 2 separation from carbon dioxide is feasible with possibilities of scalability. These results are important for consolidating hydrogen production from biological processes.