Pedro Nel Alvarado

Actualmente existe una alta preocupación mundial asociada a las emisiones de gases de efecto invernadero entre los cuales el dióxido de carbono (CO2) juega un papel principal. Por lo tanto, el interés de la comunidad académica e industrial es alto para encontrar alternativas para la captura de CO2 en los procesos de altas emisiones y en este sentido el uso de sorbentes se plantea como una alternativa prometedora. Teniendo en cuenta lo anterior, este estudio evalúa la viabilidad de utilizar óxido de calcio (CaO) derivado de cáscaras de huevo como sustituto del carbonato de calcio (CaCO₃) en la fabricación de sorbentes para la captura de CO₂. Los sorbentes se prepararon combinando MgO con CaCO₃ o CaO preveniente de cáscaras de huevo, utilizando dos métodos de mezcla (vórtex y molienda manual), seguidos de un tratamiento térmico. Los resultados de los análisis termogravimétricos (TGA) y la caracterización mediante difracción de rayos X (DRX) mostraron que ambos materiales, basados en CaO y CaCO₃, tienen una capacidad similar para capturar CO₂. Este hallazgo demuestra que el CaO derivado de este residuo puede ser una alternativa efectiva y más sencilla que el CaCO₃, facilitando la fabricación de absorbentes para la mitigación del cambio climático.

Spent mushroom compost (SMC) is a waste byproduct generated by the mushroom industry, with the current disposal methods involving landfills or incineration, causing environmental problems. This study introduces a cascading valorization based on circular economy. A water-washing pretreatment is suggested to reduce the ash content and improve the calorific value. Furthermore, an oxidative torrefaction is proposed to enhance the physicochemical properties and evaluate the residence time, temperature, and initial weight effects. The investigation revealed that the calorific value increased by 49.46% in the best water washing scenario and the SMC contains laccase. During SMC torrefaction, mass and energy yields exceeded 80%, and the calorific value was improved. Finally, torrefaction in situ CO₂ capture was achieved by forming CaCO₃, with a mass fraction increase of up to 7.4%. The study describes the cascading innovation use of this residue on a TRL4 higher than previously reported studies, thereby contributing to gaining an understanding of sustainable industrial mushroom production.

Epidemiological studies have consistently linked air pollution to severe health risks. One strategy to reduce the impact of combustion products from engines is adding additives to the fuel. Potential benefits have been observed in terms of performance and emissions, as well as in decreasing fuel consumption. However, the associated emission of particulate matter into the environment may have unforeseen health effects. This study examines the effects of diesel exhaust particles (DEPs) from diesel fuel mixed with amide-functionalized carbon nanotubes (CNTF). The aim is to analyze the properties of DEPs and determine their toxic effects on lung cells. The DEPs were characterized using scanning and transmission electron microscopy, while the polycyclic aromatic hydrocarbons (PAHs) were analyzed through gas chromatography. Various assays were conducted to assess cell viability, apoptosis, oxidative stress, and DNA damage. The addition of CNTF to diesel fuel altered the morphology and size of the particles, as well as the quantity and composition of PAHs. At the cellular level, diesel DEPs induce higher levels of reactive oxygen species (ROS) production, DNA damage, apoptosis, and cytotoxicity compared to both CNTF and diesel–CNTF DEPs. These findings suggest that the nano-additives enhance energy efficiency by reducing pollutants without significantly increasing cell toxicity.

This study focuses on applying ash reduction treatments in order to explore the potential for industrial-scale thermochemical utilization of Spent Mushroom Compost (SMC). SMC is a waste byproduct generated by the mushroom industry. Typically, for every kilogram of produced mushrooms, five kilograms of SMC are discarded, with current disposal methods involving landfills or incineration, causing environmental problems. Utilizing SMC effectively presents challenges due to the inherent properties of this biomass type, characterized by high moisture and ash content, low fixed carbon content, and material heterogeneity. These attributes create difficulties when employing a thermochemical valorization route due to the low carbon content and mineral treatments involved. The results have unveiled the heterogeneous nature of the material and its individual components when physically separated. Among the three identified fractions (agglomerated, woody, and fines), the woody fraction showed the highest potential for thermochemical utilization. Notably, when subjected to washing with distilled water and citric acid treatments, it resulted in up to 66% ash reduction, a significant outcome. Other fractions of the material may find potential applications in agriculture. The effective utilization of such high-volume waste biomasses demands diverse and innovative approaches, underlining the urgency and complexity of the problem and the need to employ the principles of a circular economy.

The intensive use of fossil fuels contributes significantly to global warming and the growing world energy crisis. Thus, it is necessary to develop alternative energy sources that make the energy matrix more flexible and reduce environmental impacts. An outstanding option is the conversion of residual biomass into energy because it produces a low-emission fuel in terms of CO₂. Therefore, this study aimed to improve the physicochemical properties of two residual biomasses (i.e., pine sawdust and spent coffee ground, SCG) through a torrefaction process. Biomass valorization was carried out in a bench-scale screw reactor (2.8 kg/h). The effect of temperature was evaluated between 200 °C and 300 °C, and the torrefied biomasses were characterized by instrumental techniques: calorific value, infrared spectroscopy analysis, thermogravimetric analysis, and scanning electron microscopy. Both biomasses exhibited an increase in calorific value when the process temperature was raised. This behavior is associated with the thermal degradation of the hemicellulose fraction and the increase in fixed carbon. In addition, the infrared analysis showed a decrease in OH and H-O-H signals associated with polar functional groups. These results show the high potential of the valorization of these two biomasses thanks to the decrease in polar groups, which have a great affinity with water, and the obtaining of calorific values close to those of fossil fuels such as lignite or sub-bituminous coal.

The textile sector, an important economic driving force in Antioquia, Colombia, uses great quantities of thermal energy mainly produced by coal combustion, which holds enormous potential for recovery. One of the most common processes in a textile plant is heat setting, which uses a significant amount of thermal energy to adjust the properties of fabrics, such as shrinking, stiffness, pull strength, width, and stretching. In this study, we calculate the mass and energy balances of a stenter and propose a system to recover the energy available in its exhaust gases. The energy recovery potential in this heat setting process is 800.97 kW, which represents 87.2% of the total input energy. Additionally, we evaluate different heat exchangers to recover the available heat and present criteria to select them. Finally, thermosyphons, whose thermal efficiency was theoretically determined here, offer a promising alternative for heat recovery from actual stenters.

This article aims to simulate an algorithm constructed in MATLAB to represent the catalytic conversion of SYNGAS into methanol in a packed-bed reactor, based on chemical kinetics for a heterogeneous system with a Cu/ZnO/Al2O3 as a catalyst, and complementary math and phenomenological models, as a pressure drop and catalyst deactivation. Model validation is developed, comparing reference results and the results by running the algorithm in MATLAB using a reference SYNGAS composition. Also, the constructed model considers a catalyst deactivation by sintering and pressure drop along the reactor. Several parameters were evaluated to identify the pro conditions for methyl alcohol production; these parameters include the gasifying agent selection, the biomass and steam ratio effect, and the biomass origin. El objetivo de este artículo es simular un algoritmo construido en MATLAB para representar la conversión catalítica de SYNGAS en metanol en un reactor de lecho empaquetado, basados en la cinética química para un sistema heterogéneo con un Cu/ZnO/Al2O3 como catalizador, y en modelos matemáticos y fenomenológicos, como caída de presión y desactivación del catalizador. Se realiza una validación del modelo, comparando los resultados de referencia y los resultados obtenidos al ejecutar en el algoritmo MATLAB la composición de referencia SYNGAS. Además, el modelo construido considera una desactivación del catalizador por sinterización y caída de presión a lo largo del reactor. Se evaluaron varios parámetros para identificar las condiciones para la producción de alcohol metílico; Estos parámetros incluyen la selección del agente gasificante, el efecto de la relación de biomasa y vapor y el origen de la biomasa.

Heat treatments, such as steel tempering, are temperature-controlled processes. It allows ferrous steel to stabilize its structure after the heat treatment and quenching stages. The tempering temperature also determines the hardness of the steel, preferably to its optimum working strength. In a tempering furnace, a heat-resistant fan is commonly employed to generate moderate gas circulation to obtain adequate temperature homogeneity and heat transfer. Nevertheless, there is a tradeoff because the overall thermal efficiency is expected to reduce because of the high rotating speed of the fan. Therefore, this study numerically investigates the thermal efficiency changes of an electric tempering furnace due to changes in the rotating speed of the fan and the effects on temperature homogeneity and the heat transfer rate to the load. Heat losses through the walls were calculated from the external temperature measurement of the furnace. Four different speeds were simulated: 720, 990, 1350, and 1800 rpm. Thermal homogeneity was improved at higher rotating speeds; this is because the recirculation zone caused by the fan improved the flow mixing and the heat transfer. However, it was found that the thermal efficiency of the tempering furnace decreased as the rotating speed values increased. Therefore, these characteristics should be modulated to obtain a profit when controlling the rotating speed. For example, although thermal efficiency decreases by 20% when the rotating speed is doubled, the heat transfer rate to load is increased by up to 50%, which can be beneficial in decreasing the process of tempering times.

Chlorogenic acid (CGA), a high value-added phytochemical used by the pharmaceutical and food industries, is found in residues and byproducts of the coffee industry. This paper presents a methodology to identify the adequate solvents to extract CGA from coffee pulp based on Hansen solubility parameters (HSPs), risk assessment, sustainability evaluation, and an economic analysis. In total, 16 solvents with different physicochemical properties, which are commonly used in the industry for extraction processes, were evaluated. According to the results, the most appropriate solvents are water, methanol, ethanol, n-propanol, acetone, t-Butyl alcohol, ethyl acetate, acetic acid, benzyl alcohol, and phenol. However, water, ethanol, and a mix of them are the most advisable solvents because they have the lowest Ra, their HSPs are near those of CGA, they are easy to handle according to CHEM21’s Risk Assessment guide, they have a lower carbon footprint, and they are less expensive solvents.