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This mini-review is intended to explore the innovative applications of nanoparticles (NPs) in biogas upgrading, emphasizing their capacity to enhance biogas quality. Numerous studies underscore how NPs, when applied during anaerobic digestion, can boost not only the quantity but also the quality of the produced biogas, leading to reduce significantly the concentration of hydrogen sulphide or even to remove it completely. Moreover, NPs are proving to be excellent alternatives as adsorbent materials, achieving up to 400mgH2S g−1 NPs. In addition, new studies are exploring the application of NPs to increase the efficiency of biological treatments thanks to their unique features. This review also emphasizes the potential benefits and addresses the challenges that need to be overcome for these technologies to reach their full potential, ultimately contributing to the development of a sustainable and environmentally friendly energy landscape.

In this study, four different plastic materials usually used in the agricultural sector (polystyrene film (PS), polyethylene terephthalate film (PET), low-density polyethylene film (LDPE) and linear low-density polyethylene film (LLDPE)) were subjected to different abiotic treatments, including photo-oxidation (ultraviolet and e-beam radiation) and thermochemical treatments, to enhance polymer degradation. The extensive use of these polymers leads to large amounts of plastic waste generation, including small plastic pieces, known as microplastics, which affect the quality of the agricultural environment, including soil fertility and quality. Therefore, polymer degradation strategies are needed to effectively reduce plastic waste to protect the agricultural sector. The degree of polymer degradation was assessed by the use of thermal and spectroscopic analyses, such as TGA and FTIR. In addition, efficiency, cost–benefits, and potential side-effects were also evaluated to propose the optimal degradation strategy to reduce plastic waste from the point of view of efficiency. The results obtained showed that the pre-treatments based on photo-oxidation (ultraviolet B and C and e-beam radiation) were more efficient and had a better cost–benefit for the degradation of the polymers studied in relation to the thermochemical treatments. Specifically, ultraviolet photo-oxidation worked well for PS and PET, requiring low energy and medium times. However, e-beam radiation was recommended for PE (LDPE and LLDPE) degradation, since high energy and long times were needed when ultraviolet energy was applied to this polymer. Furthermore, the overall efficiency of the plastic degradation of pre-treatments should be studied using a multicriteria approach, since FTIR assessments, in some cases, only consider oxidation processes on the plastic surface and do not show the potential integrity changes on the plastic probes.

Experimental vapor–liquid equilibrium (VLE) data, and the activity coefficient model parameters obtained by their correlation, are frequently used in separation processes design. The inspection of this information for ternary systems has revealed some problems that are not widely known and could lead to serious mistakes. A small sampling of ten ternary systems, with VLE data sets at constant pressure, arbitrarily selected has been considered to illustrate these problems. The experimental VLE data and the NRTL model parameters for these systems have been taken from different sources, one database and two commercial simulation packages. A MATLAB code has been developed to prepare 3D graphs where the T/x and T/y surfaces calculated by the activity coefficient model (NRTL) are represented along with the experimental VLE data. The results of the analysis of this small sample are very worrying. In fact, half of the selected systems present severe inconsistences between the experimental VLE data and the T/x,y surfaces calculated using the correlation results published or implemented in the simulation software. These inconsistences are of different natures, but the most notable is the existence of parameter sets that do not correlate at all the VLE behavior of the system that they supposedly represent. These irregularities may occur only in the ternary region, only in the binary subsystems, or, in some cases, in both. These problems go frequently unnoticed for different reasons. As discussed in this work, the typical 2D graphs and deviations in T or P and vapor composition are not enough in some cases so as to have an adequate idea of both the quality of the data and the suitability of the model to represent them. This is particularly true when considering, as is strongly advisible, the complete set of data, i.e. the ternary and binary VLE data simultaneously. Some recommendations are presented in this work to overcome the problems detected both when planning the experiment

La presente investigación se enfoca en la subcuenca del Río Chiquito, una región donde aproximadamente el 27 % de su territorio se encuentra completamente urbanizado. El sistema hidrogeológico exhibe características distintivas, comprendiendo acuíferos fracturados, porosos y multicapa que operan como una única unidad. La zona de recarga, en parte protegida por su ubicación en la zona de amortiguamiento y núcleo del Parque Nacional La Tigra, se encuentra en los acuíferos fracturados del Grupo Padre Miguel, seguidos por los acuíferos multicapa de la Formación Río Chiquito. En la parte baja de la subcuenca se localiza la zona de descarga, con alto aprovechamiento de pozos por la mayor densidad de población, y donde el territorio se encuentra completamente urbanizado. El análisis hidroquímico de las aguas subterráneas (manantiales y pozos) muestra que en la parte alta de la cuenca las aguas presentan una facies bicarbonatada cálcica, mientras que en la parte baja son aguas selenitosas, es decir, con elevadas concentraciones de sulfato. Los recursos hídricos de esta unidad se encuentran en un estado crítico debido a la extracción exhaustiva de agua en los pozos, agravando la situación los materiales propios de la geología local y los procesos edáficos, que contribuyen al empeoramiento de la calidad del agua, con incremento en la presencia de metales pesados, como arsénico, cadmio, manganeso, zinc y estroncio, así como por las altas concentraciones de sulfatos, comprometiendo la salud humana de los usuarios de estos puntos de aprovechamiento. Se determinó la zonificación de los riesgos asociados a la salud humana, identificando la parte baja de la subcuenca como un área con alto riesgo debido a aguas selenitosas y a contaminantes metálicos, junto con elevadas tasas de contaminación microbiológica encontradas en más del 50 % de los pozos evaluados, dando como consecuencia un índice de calidad del agua que oscila entre pobre y marginal. Para abordar estos problemas, se prop

Sugarcane bagasse (Saccharum officinarum) is a widely spread residual biomass from the sugar industry that can be valorized through pyrolysis. The spectrum of the fractions obtained will vary depending on the pyrolysis conditions selected. In this work, the influence of alkaline treatments on the raw material has been studied. The sugarcane residues were treated with sodium or potassium hydroxides (1:1 sample/hydroxide ratio) and subsequently washed to remove hydroxides. Slow pyrolysis in a thermobalance connected to FTIR and flash pyrolysis in an EGA/Py-GC/MS system were performed with three types of samples, i.e.: raw material, hydroxides impregnated bagasse and the material obtained after washing the previous impregnated samples to remove the hydroxides. The experiments carried out allow us to distinguish between the effect of the basic pretreatment and the catalytic effect of the alkaline ions present during the pyrolysis on the compounds generated, thus allowing us to analyze the advantages that these processes can present in the bagasse valorization. According to the results obtained, the presence of alkaline ions in the sample during the pyrolysis process increases char percentage very significantly as well as cyclopentanone and cyclopentenone derivatives and the amount of CO2 evolved, reducing levoglucosane drastically and the vinyl and methoxy groups in the volatiles obtained. The washing treatment until neutral pH, after the alkaline impregnation, modifies the spectrum of pyrolytic products obtained, reducing phenol derivatives and increasing very significantly the percentage of levoglucosane and hydroxiacetaldehyde. Thus, the changes in the bagasse structure as well as in the decomposition mechanism could be tuned to produce activated carbon in a single step (maximizing carbon yield), diminishing the oxygen content in the bio-oil obtained (increasing its heating value) and reducing the pyrolytic compound spectrum (increasing the selectivity of the process

The fluctuation in the consumption of treated water is a situation that distribution networks gradually face. In times of greater demand, this consumption tends to suffer unnecessary impacts due to the lack of water. The uncertainty that occurs in water consumption can be mathematically modeled by a finite set of scenarios generated by a normal distribution and attributed to the network design. This study presents an optimization model to minimize network installation and operation costs under uncertainties in water demands. A Mixed Integer Nonlinear Programming model is proposed, considering the water flow directions in the pipes as unknown. A deterministic approach is used to solve the problem in three steps: First, the problem is solved with a nominal value for each uncertain parameter. In the second stage, the problem is solved for all scenarios, with the independent variables of the scenario being fixed and obtained from the solution reached in the first stage, known as the deterministic solution. Finally, all scenarios are solved without fixing any variable values, in a stochastic approach. Two case studies were used to test the applicability of the model and global optimization techniques were used to solve the problem. The results show that the stochastic solution can lead to optimal solutions for robust and flexible water distribution networks, capable of working under different conditions, considering the uncertainties of node demand and variable pipe directions.

In this study, the influence of the incorporation of eucalyptus (EO), tea tree (TT) and rosemary (RO) essential oils and Chiriyuyo extract (CE) on the structure and properties of thermoplastic starch (TPS) obtained from potato starch, glycerin and water was evaluated. All oils and the extract were used at a concentration of 0.5 g/100 g of TPS, while for TT, the effect of the concentration was also studied. The mixtures obtained were processed by extrusion and thermocompression molding. The sheets were characterized by XRD, FTIR, TGA, SEM and analyses of their mechanical properties, antimicrobial characteristics and biodegradability. The results show that the use of small concentrations of the oils in 70TPS does not induce changes in the TPS structure according to the results of XRD, FTIR and TGA, with each essential oil and CE affecting the mechanical properties unevenly, although in all cases, antimicrobial activity was obtained, and the biodegradability of TPS in soil was not modified. An increase in the concentration of TT in 60TPS causes marked changes in the crystallinity of TPS, providing a greater modulus with a higher concentration of TT. Regardless of the amount of TT, all sheets maintain antimicrobial characteristics, and their biodegradation in soil is delayed with a higher oil content.

Los plásticos han llegado a ser una parte integral de nuestra vida cotidiana, desplegando una amplia gama de beneficios en diversos aspectos. A pesar de su contribución positiva al aumento de nuestro nivel de vida, la persistencia y la gestión inadecuada de los plásticos plantean desafíos significativos para el medio ambiente. En aras de avanzar hacia una economía circular más sostenible, es imperativo aumentar la proporción de plástico reciclado. En este sentido, se enfoca en la necesidad de obtener plásticos reciclados de alta calidad, libres de contaminantes. Para conseguirlo, en esta investigación se desarrolló un método analítico que permite cuantificar diversos contaminantes, como los hidrocarburos aromáticos policíclicos (PAHs), los dioxinas y furanos policlorados (PCDD/Fs), los bifenilos policlorados similares a dioxinas (PCBs) y distintos tipos de bisfenoles (BPA, BPS, BPF y BPM). Con el método analítico establecido y tras verificar la presencia de diferentes niveles de contaminantes, se procedió a investigar un proceso óptimo de descontaminación. Se exploraron varias técnicas y se identificó un método que, mediante condiciones de temperatura moderadas y el uso de solventes o reactivos no perjudiciales para el medio ambiente, logró reducir de manera significativa el contenido de contaminantes en el plástico reciclado. Este avance representa un hito importante, ya que podría permitir que el plástico reciclado posea propiedades iguales a las del plástico virgen, abriendo así nuevas posibilidades de aplicación en mercados previamente inaccesibles. Este proceso de descontaminación tiene el potencial de ampliar significativamente el uso de plásticos reciclados en diversas aplicaciones, contribuyendo así a la transición hacia una economía más circular y sostenible. Este estudio, por tanto, no solo aborda la necesidad crítica de mejorar la gestión de los plásticos y reducir su impacto ambiental, sino que también ofrece una solución innovadora y práctica para hacer

Este Trabajo de Fin de Grado (TFG) aborda dos desafíos contemporáneos: la gestión de los residuos orgánicos generados en el sector agrícola y ganadero (agropecuario) y la búsqueda de una vía sostenible para la transición energética, orientada a dejar atrás el uso de combustibles fósiles. En el contexto actual, donde la necesidad de energía renovable y la reducción de emisiones de gases de efecto invernadero (GEI) son importantes, ambos objetivos se encuentran interconectados mediante el proceso de digestión anaerobia (DA), donde contribuyendo a la economía circular y transición energética, los desechos agropecuarios son transformados en recursos energéticos, entre otros. Como se mostrará en el presente estudio, el aprovechamiento de estos residuos no solo facilita una transición energética más limpia y sostenible, sino que también aborda la problemática de la gestión adecuada de residuos, lo cual reduce las emisiones de GEI. Es por ello por lo que actualmente dicha vía se presenta como una solución innovadora que promueve beneficios económicos, sociales y ambientales significativos. De esta manera, se ofrecerá una visión integral de los beneficios que esta práctica implica en cuanto a la consecución de los Objetivos de Desarrollo Sostenible (ODS), haciendo hincapié en el ODS 11, que promueve ciudades sostenibles. Desde el punto de vista experimental, este trabajo explorará el potencial metanogénico de la producción de biogás a partir de distintos desechos, principalmente ganaderos, mediante digestión anaeróbica (DA). Se analizará cómo esta técnica puede ser una alternativa viable y eficaz, destacando su potencial y los factores influyentes para mejorar el proceso e impulsar la sostenibilidad y eficiencia energética en el sector rural, mostrando los impactos económicos y ambientales positivos tras la implantación de una planta de biogás.

En un contexto donde las enfermedades raras a menudo carecen de la atención necesaria, el presente trabajo se enfoca en la Enfermedad de Wilson, una patología hereditaria que forma parte de este conjunto de condiciones médicas con escasa visibilidad, caracterizada por la acumulación excesiva de cobre en el organismo humano. Con el propósito de mejorar la calidad de vida de los pacientes, se propone una vía de administración alternativa del tratamiento a través de parches transdérmicos, utilizando sales de zinc como principio activo y aprovechando las características del almidón termoplástico (TPS) como material base. Este polímero, conocido por su biocompatibilidad y biodegradabilidad, puede utilizar el alcohol polivinílico (PVA) como coadyuvante con el fin de mejorar sus propiedades. El proceso de desarrollo consiste en la elaboración de varios films cargados con diferentes cantidades de acetato de zinc mediante la técnica casting, mezclando los diferentes componentes en exceso de agua sobre una superficie plana y dejando que se evapore para obtener una película delgada y uniforme. De forma previa a la incorporación del fármaco a los parches, se realiza la optimización, tanto de la formulación, como del proceso de obtención del almidón termoplástico, para garantizar la mejor calidad posible. Tras la optimización, se lleva a cabo la preparación de los parches con fármaco. Estos parches son sometidos a diversos ensayos para evaluar sus características, destacando el análisis cinético de liberación del fármaco en un medio salino que simula los fluidos corporales. Los resultados obtenidos proporcionan una evaluación de la viabilidad y eficacia de los parches desarrollados, confirmando su capacidad para ofrecer una liberación controlada del fármaco.

Water parks often use chlorine for water disinfection despite its ineffectiveness and health risks. This research explored the efficacy of combining electromagnetic treatment (EMT) with chlorination in disinfecting swimming pool water. Water samples, with different organic loads, were subjected to EMT-chlorination tests. EMT significantly affected the physicochemical parameters of the water, notably reducing turbidity by 50 % and decreasing COD levels compared to systems without EMT. The system with EMT reported lower chlorine consumption, suggesting a lower formation of chlorogenic by-products. Therefore, it is evident that the combined method can decrease the levels of organic contamination in the water, reduce the presence of algae, and minimize the consumption of conventional chemical disinfectants, thus reflecting an interesting synergy between EMT and chlorination, which could be advantageous from a health, environmental and economic perspective.

El tratamiento electromagnético (EMT) se está utilizando para evitar incrustaciones, pero tiene además otros efectos, ya que puede afectar a la población de algas o microrganismos, según se ha observado en recientes ensayos de laboratorio llevados a cabo en el Instituto de Ingeniería de Procesos Químicos (IIPQ) de la Universidad de Alicante, con agua tomada de “Terra Natura” (Benidorm, Alicante), en concreto de la piscina donde habitan leones marinos. En este trabajo se tratará de determinar los efectos producidos en algas cultivadas procedentes de esta piscina, sometidas a EMT en ensayos de laboratorio controlados. Se ha comprobado que proliferan microalgas destacando las del género “Chlorellas” y para cuantificar los efectos de EMT a mayor escala es crucial llevar a cabo su cultivo, siendo uno de los objetivos prioritarios de este trabajo conocer el medio de cultivo que permita maximizar la producción de estas microalgas y a su vez comparar con el crecimiento de "Espirulina”. Se utilizaron cuatro medios distintos y se compararon parámetros físico-químicos medidos como la conductividad, el pH, la temperatura, la densidad óptica y el peso seco durante 3 semanas y se seleccionó el medio que mejores resultados presentó para el agua de Terra Natura. Una vez el cultivo estuvo listo, se llevó a cabo el EMT durante 14 días mediante el equipo TK3K, comparando los mismos parámetros utilizados para los cultivos y además determinando clorofilas totales. Para ver la diferencia, se realizó en paralelo otro ensayo sin tratamiento, con la hipótesis de que en la muestra tratada electromagnéticamente la concentración microalgal disminuiría. Los resultados visuales sugieren que la hipótesis se confirma, ya que se observó un cambio en la coloración de los tanques, con un tono verde más intenso en el tanque no tratado. Además, las mediciones de clorofila y peso seco respaldan esta conclusión, mostrando una concentración menor en el tanque tratado. Las variaciones del pH fueron mínimas

El objetivo de este estudio es determinar la capacidad de almacenamiento energético del material obtenido de cascarilla de cacao en configuración de capacitor. El material lignocelulósico proviene de la cosecha de cacao ecuatoriano utilizado en procesos agroindustriales. Se realizó el análisis de los volátiles generados durante la pirólisis instantáneo mediante la técnica GC/MS; además, de la comparación del capacitor con dos electrólitos diferentes: ácido sulfúrico (H2SO4) y cloruro de sodio (NaCl). El procesamiento del material se realizó mediante un proceso de carbonización y otro de activación por vía química, los cuales se llevaron a cabo en un reactor de pirólisis en atmósfera inerte de nitrógeno (N2) a una velocidad de calefacción de 20 oC min-1 y se activaron a 850 oC en la misma atmósfera por 4 horas. A partir de este material se prepararon los electrodos y se probó mediante voltametría cíclica el almacenamiento de energía a diferentes velocidades de barrido para cinco ciclos. Los resultados del análisis GC/MS y de voltametría cíclica demostraron que la materia prima secundaria preparada puede utilizarse para obtener productos de alto valor agregado. Los principales compuestos volátiles identificados corresponden a fenoles, ácido acético y alcoholes. El máximo potencial fue de 1,1 kW kg-1 con electrolito de NaCl y, la máxima durabilidad se logró con electrolito de H2SO4 con una potencia de 0,29 kW kg-1 estos valores fueron obtenidos a una velocidad de 100 mV s-1., The purpose of this study is to determine the energy storage capacity of the material obtained from cocoa husks in a capacitor configuration. The lignocellulosic material comes from Ecuadorian cocoa harvests used in agro-industrial processes. Analysis of the volatiles generated during instant pyrolysis was conducted using GC/MS technique. Additionally, a comparison of the capacitor with two different electrolytes was made: sulfuric acid (H2SO4) and sodium chloride (NaCl). The material processing involved carbonization and chemical activation processes, carried out in a pyrolysis reactor under an inert nitrogen (N2) atmosphere at a heating rate of 20 °C min-1, and activated at 850 °C in the same atmosphere for 4 hours. Electrodes were prepared from this material and tested using cyclic voltammetry to assess energy storage at different scan rates for five cycles. The results of the GC/MS analysis and cyclic voltammetry demonstrated that the prepared secondary raw material can be used to obtain high-value added products. The main identified volatile compounds include phenols, acetic acid, and alcohols. The maximum potential was 1,1 kW kg-1 with NaCl electrolyte, and the maximum durability was achieved with H2SO4 electrolyte with a power of 0,29 kW kg-1; these values were obtained at a scan rate of 100 mV s-1.

This study examines the presence of bisphenol A (BPA), S (BPS), F (BPF), and M (BPM) in various recycled plastics readily available on the market (LDPE, HDPE, PET, and PP), in light of European Food Safety Authority (EFSA) limits. Twenty samples of different origin are analyzed, cleaning treatments are applied, and the migration potential of these bisphenols into food is studied. BPM is absent in all samples, but a post-consumer recycled LDPE sample reveals high bisphenol concentrations, raising concerns, reaching 8540 ng/g, 370 ng/g, and 29 ng/g of BPA, BPS, and BPF, respectively. Migration tests show substantial migration of these contaminants into food simulants. Using a cleaning treatment with polyethylene glycol (PEG 400) reduces BPA in LDPE, HDPE, PP, and PET samples by 95%, 99%, 97% and 28%, respectively, highlighting the importance of cleaning treatments across various polymers in plastic recycling. These findings not only protect food safety but addressing environmental challenges associated with plastic recycling.

El presente trabajo fin de grado tiene por objeto la simulación de una planta de producción de etilenglicol a partir de la hidrólisis no catalítica de óxido de etileno, así como el diseño del sistema de control del reactor continuo de tanque agitado donde tiene el proceso de reacción. Para ello, en primer lugar, se realizan unos estudios previos con el fin de comprobar la bondad de los parámetros cinéticos y de determinar la relación agua/óxido de etileno en el reactor, que es uno de los parámetros más importantes para controlar la formación de glicoles por el proceso convencional de hidrólisis no catalítica. Una vez finalizados, se realiza la simulación en estado estacionario del proceso en estudio utilizando el simulador de procesos químicos Aspen HYSYS V12. Dicho proceso está conformado por tres zonas: la zona de reacción, la zona de evaporación de agua y la zona de purificación. Con ello, gracias a la combinación de Aspen HYSYS V12 y MATLAB, se propone la optimización de las condiciones de operación de la zona de evaporación para la obtención de un perfil de presiones factible buscando el mayor ahorro energético al minimizar el uso de los servicios. De esta forma, se establecen las mejores condiciones de operación posibles. Tras definir el proceso, se propone el diseño del sistema de control para el reactor, recurriendo a las técnicas clásicas de control (lazos de control por retroalimentación). Todo ello, se realiza a través de la herramienta Aspen HYSYS Dynamics con la cual se simula el reactor en estado transitorio y se evalúa el sistema de control bajo diferentes escenarios. Por último, se desarrolla un estudio económico del proceso con tal de estimar los costes que supone la implementación del proceso industrial seleccionado para la producción de etilenglicol.

This research delves into a detailed exploration of the thermal decomposition behavior of bio-based polymers, specifically thermoplastic starch (TPS) and polylactic acid (PLA), under varying heating rates in a nitrogen atmosphere. This study employs thermogravimetry (TG) to investigate, providing comprehensive insights into the thermal stability of these eco-friendly polymers. In particular, the TPS kinetic model is examined, encompassing the decomposition of three distinct fractions. In contrast, PLA exhibits a simplified kinetic behavior requiring only a fraction described by a zero-order model. The kinetic study involves a systematic investigation into the individual contributions of key components within TPS, including starch, glycerin, and polyvinyl alcohol (PVA). This detailed analysis contributes to a comprehensive understanding of the thermal degradation process of TPS and PLA, enabling the optimization of processing conditions and the prediction of material behavior across varying thermal environments. Furthermore, the incorporation of different starch sources and calcium carbonate additives in TPS enhances our understanding of the polymer’s thermal stability, offering insights into potential applications in diverse industries.

Parcial Energía 2024

La hidroxiapatita es uno el principal componente inorgánico de los huesos. Continuamente se está investigando nuevos materiales que sirvan de andamiaje para estimular la regeneración ósea. Recientes estudios indican que materiales compuestos hidroxiapatita-grafeno han dado buenos resultados en experimentos de regeneración ósea dada la gran fortaleza de las láminas de grafeno a nivel atómico y la forma de crecer los cristales de hidroxiapatita sobre el grafeno. En el presente trabajo se sintetizará hidroxiapatita sintética por el método de valoración en una suspensión de grafeno oxidado para cantidades finales de grafeno del 1 y 2% en peso. El efecto que tiene el grado de exfoliación y de tamaño de plano que presenta el grafeno no se ha estudiado previamente en los compuestos con hidroxiapatita. Se emplearán dos tipos de grafeno oxidado con diferente grado de exfoliación y tamaño de hojuela, que serán preparados por aplicación de ultrasonidos. Una vez sintetizados los compuestos, se caracterizarán convenientemente mediante miocroscopía electrónica, difracción de rayos X y técnicas espectroscópicas, y se medirá el efecto bioactivo de regeneración ósea en una disolución de fosfatos.

The formation of calcium carbonate scale in pipes and devices in water supply networks poses serious problems. Electromagnetic treatment (EMT) is a technology that can prevent the formation of these scales without the need to add chemical reagents, reducing maintenance costs in the installations. In this work, the types of crystals commonly found in water distribution systems are studied, with emphasis on the different techniques that allow their characterization (TGA, XRD, SEM), and the effects that EMT produces on their morphology. Laboratory trials have been carried out with synthetic water prepared from a calcium carbonate solution to study the crystals obtained at different temperatures, with and without EMT. High temperatures cause the production of aragonite instead of the stable form (calcite), as was observed in the samples from the heater resistors. In contrast, in the samples taken in lower temperature zones, a majority presence of calcite was observed. These results have been corroborated with a laboratory-scale evaporation trial, obtaining an increase in the aragonite/calcite ratio with increasing temperature and with the treatment applied, generating crystalline phases that exceed 70% aragonite (needle shape). It is highlighted that the EMT limits the reversion of aragonite to calcite and decreases the formation of scale.

Phase equilibria for systems that present different types of azeotropy have been analyzed by using the dimensionless Gibbs energy of mixing (gM) for the liquid and vapor phases along with both the common tangent criterion and the phase stability test. First, the gM,L function for the liquid phase and its derivatives have been analyzed to obtain the boundary function between the homogeneous (L) and heterogeneous (LLE) regions as a function of the parameters for different activity coefficient models. Next, the excess Gibbs free energies and their first derivatives for the liquid and vapor phases have been analyzed to determine the mathematical conditions and the limits of different types of azeotropy (VLE and VLLE) and the possible combinations of two azeotropes in the same binary system. Finally, as a result of the combination of all this information, azeotropy and miscibility maps have been obtained as a function of the parameter values for Margules, van Laar, Wilson, and NRTL activity coefficient models.

Composting is a common treatment for the high amounts of sewage sludge produced in wastewater treatment plants, and the product is used in agriculture. Composting reduces the levels of biodegradable organic pollutants, although other compounds present in wastewater and not eliminated previously by conventional physical–chemical and chemical treatments, such as polychorodibenzo-p-dioxins/furans (PCDD/Fs) and polychlorinated biphenyls (PCBs), have been found in the final compost at higher levels than those observed in the initial sludge. Their formation was studied during composting under unfavorable aeration conditions and paying attention to different stages of the process. Experiments were carried out in small vessels inside a controlled oven for three types of sewage sludge. Pentachlorophenol was previously added as a dioxin precursor. A clear formation of PCDD/Fs was found, especially during the maturation stage for two experiments. Mainly octachlorodibenzo-p-dioxin (OCDD) and 1234678-heptachlorodibenzo-p-dioxin (1234678-HpCDD) to a lesser extent were formed. OCDD levels in the final samples were around 10 times higher than those of the initial mixture after removing the concentration effect. No clear formation nor degradation of PCBs was observed. The toxicity values due to PCDD/Fs and PCBs found in the initial mixtures were 1.20–2.46 ng WHO-TEQ/kg, and those from the final samples were 2.30–7.86 ng WHO-TEQ/kg. Although the toxicity values are below the most restrictive limits found in Europe in this case, toxicity could increase considerably with the presence and concentration of other precursors. Compost from sewage sludge is an ecological product, but the operating conditions must be controlled to avoid PCDD/F formation and facilitate degradation of persistent organic pollutants.

The incorporation of different amounts of Gum Arabic (GA) in thermoplastic starch (TPS) obtained by extrusion and subsequent thermocompression has been studied. The sheets have been characterized by means of XRD, FTIR, TGA, moisture content, SEM, mechanical properties, antimicrobial activity and biodegradability via composting. The FTIR analysis of the sheets shows the presence of ester groups, while the TGA shows the presence of new processes and a residue much higher than expected is obtained. No changes in crystallinity are observed by XRD. The inclusion of GA confers antimicrobial properties to thermoplastic starch against the Gram + and Gram – bacteria studied even at the smaller concentrations. For a low GA content (0.5 and 1g GA/100 g TPS) a homogeneous material is observed by SEM, as well as an important increase in tensile strength, modulus and deformation at break, which are very interesting properties facing the applicability of this material in single use plastics which are in contact with food or other consumable goods. At higher contents of GA, hollows and cracks appear in the material, compromising the mechanical properties. In all cases, the inclusion of GA delays the biodegradation process in soil, which can be related to its antibacterial capacity and especially in case of GA concentrations of 2 and 5g /100 g of TPS with lower humidity of these TPS sheets.

The search for cleaner and more sustainable energy sources is increasingly growing. Aligning this demand with another environmental problem, such as sewage treatment/disposal, is a strategic priority. In light of this, the aim of this study was to estimate the energy potential of sewage generated in the Brazilian state of São Paulo (SP) by using it to produce biomethane. The study also evaluated the viability of using this byproduct of sewage treatment (biomethane) as a substitute for natural gas (NG), as both of them have similar lower heat values. To do this, information was gathered regarding the population, gross domestic product per capita, sewage collected, and natural gas consumption for each of the state’s 645 cities, and, based on this, the sewage energy potential, the amount of NG to be substituted by biomethane, and the reduction in CO2 emissions were calculated. Moreover, in order to address a possible allocation of biomethane that could potentially be produced in each SP city and sent to currently NG-consuming cities, an optimization algorithm was proposed. The results indicated a sewage energy potential of 4.68 × 109 kWh/yr for the entire SP state, which would be enough to supply around 10% of the energy value of all the NG currently consumed. It was also observed that from 130 cities with NG consumption, 10 could produce enough biomethane to fully satisfy the natural gas demand. In the elected scenario of optimization, 291 cities were found to be capable of supplying the demand of 26 cities that currently use NG. The potential to reduce CO2 emissions is between 1.81 × 106 and 2.42 × 106 ton/yr, and this range could increase if sewage treatment coverage grows. Despite the challenges inherent in extrapolating a potential study to scenarios that require significative investment, the results obtained are useful for formulating public policies for decarbonization in the near future.

Parcial Cantidad de Movimiento - marzo 2024

We live in a rapidly changing world where the economy is set to be dominated by the STEM (Science, Technology, Engineering and Mathematics) industries at the heart of technology advancements, such as engineering and computer science. In Europe, women accounted for almost one-third of the total number of people employed in the high-technology sectors in 2022. Globally, it is estimated that only 20% of engineering graduates are women. Eliminating stereotypical prejudices in engineering and supporting young girls who wish to study and work in STEM fields are key factors for the future. There are some “unconscious bias" that deters girls from pursuing STEM studies. For example, many young women, as well as their families and teachers, consider engineering to be more typical of men than women since they consider it hard and dirty. In fact, it is associated with heavy machinery that implies a need for physical strength and resistance. And, what's worse, many girls consider that it is not really useful to society. Girls at home and at school are less likely than their brothers to be encouraged to become an engineer, unless there is a significant connection in their immediate family or social group. Therefore, it is important to tackle bias among girls’ families and communities and removing stigma surrounding women in STEM. The Higher Polytechnic School at the University of Alicante (Spain) has developed a program focused on overcoming barriers to STEM degrees for girls. The “Quiero Ser Ingeniera” program has already held three editions and has the support of the university and external companies. It has two main activities: a presentation in the university auditorium attended about a thousand students (15-16 years old) and four different thematic campus attended by around a hundred girls interested in STEM degrees. In the first conference, five female engineers from different disciplines and recognized prestige participate to break down stereotypes: they describe their car

The scarcity of natural resources makes it essential to develop products that meet environmental requirements. This is also true for the water and wastewater treatment business, where even consolidated processes, such as coagulation and flocculation, must be improved, opening opportunities for searching for alternative options to conventional processes. Among the existing options, tannin-based agents (TBAs) have been highlighted in recent years due to their biodegradability and proven efficiency. However, little is known about the impacts of the production process of these agents on an operational/industrial scale. In this study, an examination of the environmental impacts of the full-scale production (more than 500 tons yearly) of a TBA from Acacia spp. (known as black acacia or mimosa) was carried out. To accomplish this, a life cycle assessment (LCA) was developed using openLCA version 2.0.0 to assess a cradle-to-gate system of 1 kg of packed TBA produced. Additionally, a comparison was made between the impacts of the production of TBA and a conventional water treatment agent, aluminum sulfate, to verify the benefits of producing the former. The most relevant impacts resulting from the production of 1 kg of TBA are observed in the following categories: global warming (1.52 kgCO2-eq); terrestrial (7.67 kg1.4-DCB-eq), freshwater (0.06 kg1.4-DCB-eq), and marine (0.08 kg1.4-DCB-eq) ecotoxicities; carcinogenic (0.10 kg1.4-DCB-eq) and non-carcinogenic (1.36 kg1.4-DCB-eq) human toxicities; and water use (0.02 m3). The main contributors to the impacts were the chemicals ammonium chloride and formaldehyde used, the transport of inputs, and the energy used. The aluminum sulfate showed better performance than the TBA for a greater number of categories; however, the normalization of the impacts showed the TBA as a very interesting option. The results obtained here can be used by TBA producers to act on the most impactful categories so that the production process becomes incr

Despite efforts to achieve gender equity in all aspects of society as one of the Sustainable Development Goals, there is still a gender gap in the number of professionals graduating from Science, Technology, Engineering, and Mathematics (STEM) careers: graduated women do not exceed 30%. In particular, the percentage of women earning degrees in engineering has remained stable at 20% for over 20 years in the United States and other countries, thus being a global situation. The percentage of undergraduate women in different engineering programs varies from a high of about 50% in fields such as environmental engineering and biomedical engineering, to a low of about 13% for computer engineering. With this approach, many Spanish universities began to develop activities to encourage vocations towards these technical degrees around the 2018-19 academic year, among them the University of Alicante. These activities are intended for high school students and consist of meetings to see, touch and experiment engineering and conferences with leading female engineers. The purpose of this study was to find out whether there is a change in trend in recent years in the enrolment of women in engineering and architecture programs in the University of Alicante, especially since actions to promote vocations began. Data from 5035 students enrolled in different engineering and architecture programs from 2018-19 to 2023-24 academic years were collected from the information system of the institution and compared to data from a previous study carried out with 25061 students from 1972-73 to 2017-18 (being 22% of them women, as expected). Data were processed differentiating by degree program, gender and academic year. As a result, the percentage of women in engineering and architecture has increased to 30% taking into account the total number of students during the last 6 years. The percentage found in the last year, when the first participants in activities of vocation promotion haven been able

Las plantas desalinizadoras necesitan de una captación de agua de mar y de una forma de gestionar el rechazo, conocido como salmuera, de una manera suficientemente eficaz y respetando las directrices respecto a la protección del medio ambiente. Teniendo en cuenta estos dos condicionantes, las plantas desalinizadoras pueden afectar al entorno en el que se encuentran debido por un lado a las grandes cantidades de agua que requieren al inicio del proceso y, por otro lado, por la evacuación de la salmuera que también puede provocar afección nuevamente en el entorno. Sabiendo de estas problemáticas, se requiere que se tomen medidas adecuadas de forma que se mitiguen dichos posibles impactos que se podrían generar. Estas medidas van asociadas a que los consumos energéticos de las instalaciones aumenten y, por ende, los costes asociados para su cumplimiento. El objeto de esta Tesis es evaluar dichos sobreconsumos energéticos y los sobrecostes económicos de dichas medidas correctoras que vienen establecidas en la regulación ambiental de las plantas desalinizadoras y compararlas con los consumos totales y los costes globales de las desalinizadoras. La experiencia adquirida desde la puesta en marcha de las diversas plantas desalinizadoras ha permitido conocer la evolución temporal del comportamiento del medio receptor con el objetivo de ir buscando una optimización de las medidas correctoras. Los resultados obtenidos se enmarcan dentro del ámbito de las desaladoras de Mancomunidad de los Canales del Taibilla (MCT), Organismo Autónomo adscrito al Ministerio Para la Transición Ecológica y el Reto Demográfico (MITERD) y cuya función para la que fue creado es para el abastecimiento de agua potable en red primaria que incluye la captación, potabilización (incluyendo desalación), conducción y almacenamiento en los distintos depósitos de reserva que se distribuyen en el ámbito geográfico de MCT. A este respecto hay que destacar que dicho ámbito casi alcanza los 12.000 km2 distribuid

Multilayer flexible packaging waste (MFPW) represents a critical issue in the field of waste management. The heterogeneous composition of this type of plastic makes its recyclability challenging. In this context, the delamination process appears to be a promising way to recycle the polymers layers separately. However, this process is still limited for a few MFPW. This work propose an innovative way to improve the delamination process using three surface modification techniques (mechanical and laser microperforation (µP), and abrasion) on the MFPW surface in order to accelerate the diffusion of the dissolving agent. The delamination was tested in a 10 % sodium hydroxide solution at 25ºC. Under this study, the mechanical µP and the abrasion gave the best results of delamination compared to the laser µP (total delamination in 25 min vs 45 min, respectively). It was concluded that the distance between the microholes was an important factor in both µP techniques.

Modular chemical process simulators are widespread in chemical industries to design and optimize production processes with sufficient accuracy. However, convergence issues and entrapment in local optima during process optimization are still challenges to overcome. To circumvent them, surrogate models of first principles simulations have attracted attention as they are easier to handle, with hybrid surrogates combining data-driven surrogate models with mechanistic equations becoming particularly appealing. In this context, this work explores the use of Bayesian symbolic regression to construct and globally optimize hybrid analytical surrogate models of process flowsheets, where some units are approximated with tailored analytical expressions rather than with neural networks or Gaussian processes, which are harder to globally optimize. Comparing with other prevalent black-box surrogate modeling & optimization approaches, such as kriging and Bayesian optimization, we find that our approach can find better solutions than using pure black-box methodologies, yet model building is much more computationally demanding.

Distillation is an energy-intensive process, and it is vital that strategies are developed to improve these processes’ sustainability. Synthesis of heat-integrated distillation sequences (HIDiS) plays a vital role in such a task. By identifying and integrating heat sources and sinks within distillation sequences, these configurations enable effective heat recovery and utilization, leading to reduced energy consumption and environmental impacts. The present work presents a new superstructure-based model with a Pinch-based operator for implicit heat integration (i.e., prediction of heat integration costs) and a stochastic solution approach for developing efficient HIDiS. Explicit heat integration (definition of heat exchanger matches) is then performed in the second part of the method. Two examples in the literature were used to validate the method. In both cases, the strategy presented was able to attain solutions with better total annual costs than those from the literature (15.8 and 11.5% lower). Solutions found with the present approach presented a greater degree of heat integration than those from the literature: more heat recovery units are present with considerably greater total heat duty (about twice greater in example 1, for instance).

Although the conversion of bioethanol into light olefins is one of the most studied processes in biorefinery schemes, there is a need to develop materials more capable of operating at industrial conditions (WHSV > 20 h-1 crude bioethanol feed). Hence, in this study, we dehydrated crude bioethanol samples derived from sugarcane fermentation to produce ethylene over a series of H-ZSM-5 zeolites. Among them, H-ZSM-5 with different Si/Al ratios (26, 280, and 371) and doped with Ce and Cu were tested on the catalytic activity and stability. Accordingly, a 26 Si/Al ratio showed full conversion and ethylene selectivity at 300 °C with a WHSV of 30.2 h-1. When doping the zeolites, a decrease in relative crystallinity and a higher amount of acid sites were observed, which affected the interaction with reactants. This interaction was deeply analyzed by the in-situ DRIFTS, which showed that ethanol adsorption is lower for doped zeolites, but the desorption rate is higher, showing higher stability over longer reaction times. Therefore, the H-ZSM-5 with a Si/Al ratio of 26 and doped with Ce maintained its activity and improved its selectivity over 140 h under more drastic conditions of WHSV (42.3 h-1). These results elucidate that Ce-doped H-ZSM-5 zeolites can improve stability and represent a starting point for large-scale crude bioethanol conversion.

In Brazil, a substantial part of its urban population has its waste disposed of at inappropriate places, such as open dumps and controlled tipping. This causes environmental impacts, in addition to disregarding the positive externalities arising from the correct waste disposal. Given this scenario, this research aimed to estimate the potential for generating electricity, considering the implementation of sanitary landfills to serve municipalities with inadequate waste disposal. The study had its methodology tested in municipalities in the most populous region of Brazil, the Southeast. A Python algorithm to calculate the methane production from the waste was created based on the software Landfill Gas Emission Model (LandGEM). Moreover, another algorithm was developed to allocate the micro plants based on the electricity generated, to optimize the logistics of the distance. The CO2 emission reduction due to sanitary landfills opening was predicted as well. If the sanitary landfills were to be implemented, an amount of 11,795.7 GWh would be generated over the 20 years of study and an average value of 467.1 million tons of CO2 would no longer be emitted per year. Public policies are necessary for this scenario to become a reality in Brazil, such as research incentives and market development.

Basados en la grave problemática ambiental actual producida por el uso indiscriminado de los plásticos y otros derivados del petróleo, así como por los nuevos cambios en la legislación ambiental de algunos países sobre la regulación y la prohibición de uso de productos a base de plásticos no biodegradables, las investigaciones se han dirigido al desarrollo de biopolímeros para la producción de biomateriales o productos que preserven el medioambiente. En la presente investigación se han elaborado y caracterizado láminas de biopolímeros a base de almidón termoplásticos (TPS) que ha sido procesado por métodos convencionales empleados en la industria de plásticos sintéticos, como son el mezclado en continuo mediante extrusión y posterior moldeo por termocompresión. Para la elaboración de los TPS se ha empleado almidones de patata, maíz y yuca utilizando como plastificantes glicerina y agua. Con objeto de tratar de reducir la elevada afinidad por el agua de las formulaciones basadas en almidón y de mejorar sus propiedades mecánicas se han empleado una serie de aditivos, todos ellos de origen natural, en concreto aceites esenciales de romero, árbol de té y eucalipto, extracto de chiriyuyo, goma arábiga, montmorillonita y quitosano. Se han elaborado un total de 37 formulaciones. En una primera fase se ha estudiado el efecto del tipo y concentración de los almidones manteniendo una proporción fija de plastificantes. Tras seleccionar una de estas formulaciones como referencia se han incorporado sobre la misma los aditivos a distintas concentraciones. Todas las láminas obtenidas se caracterizaron mediante espectroscopía infrarroja por transformada de Fourier (FTIR), contenido de humedad, solubilidad en agua, microscopía electrónica de barrido (SEM), ensayos de tracción, dureza, análisis antimicrobiano, ensayo de desintegración y análisis termogravimétrico (TGA). Las propiedades de los TPS están largamente influenciadas por el contenido y tipo de almidón. En el intervalo de co

Una de las principales dificultades de usar plástico reciclado para fabricar envases de alimentos es garantizar que no llegan contaminantes al producto final y que éste sea seguro. En el caso de los plásticos reciclados post-consumo únicamente el tereftalato polietileno (PET) tiene procesos de reciclaje para poder ser empleado nuevamente en envases alimentarios. Para ello, el PET reciclado debe cumplir una serie de condiciones (BOE-A-2011-11827 Real Decreto 846/2011, de 17 de junio, 2011). Sin embargo, para el LDPE no existe ninguna legislación que trate sobre la regulación del uso de LDPE post-consumo reciclado para fabricar envases en contacto con alimentos, cosa que hoy en día sería muy beneficiosa, puesto que ayudaría a satisfacer los objetivos de la UE. La complejidad de reciclar el plástico reside en el uso de plásticos de diversas procedencias, es decir, si se recicla un envase que originalmente contenía detergentes o productos de higiene. El principal inconveniente de seguridad con el uso de plásticos reciclados post- consumo en la fabricación de envases alimentarios son el riesgo de que los contaminantes del material original lleguen al plástico reciclado. En este TFG se trabajará en procesos de limpieza de plásticos para su reutilización.

En el presente trabajo de fin de grado se ha llevado a cabo la simulación de una planta de hidrogenación de hidrocarburos mediante el software Aspen HYSYS V12. Para ello, se ha partido de un alimento constituido por una mezcla de hidrocarburos saturados e insaturados y se ha propuesto un modelo de la planta partiendo de una ya simulada (Ordouei, 2009), a la que se le han hecho ciertas modificaciones y añadidos. Con esto, partiendo de la zona de reacción propuesta por Ordouei (2009), se proponen dos sistemas de separación distintos y se comparan las purezas obtenidas de cada uno de los productos, así como los requerimientos energéticos de cada configuración. Para determinar los requerimientos energéticos de cada una de las alternativas, se ha realizado la integración energética de la planta empleando la tecnología pinch. Así, se propone una red de intercambiadores de calor que, aunque no sea la red óptima desde el punto de vista económico, es una buena red de modo que se minimiza el uso de servicios fríos y calientes, al igual que el número de intercambiadores de calor. Por otro lado, se propone la implementación de un ciclo Brayton, que consiste en comprimir el aire antes de que entre a la cámara de combustión, donde se queman los hidrocarburos ligeros de la planta, de modo que se usan los gases calientes de salida para mover una turbina y generar electricidad. Además, se usa el calor de la combustión contenido en los gases calientes para generar vapor de agua a media y baja presión. Con esto, se obtiene energía eléctrica que se emplea para proporcionar suministro eléctrico a las diferentes bombas, compresores y edificios de la planta, así como vapor de agua a media y baja presión que se usa como servicio caliente. Por último, se ha realizado un análisis económico de la planta con el sistema de separación seleccionado, con lo que se han obtenido los costes de la misma.

This study provides the complete liquid–liquid equilibrium (LLE) data including the solubility curves and tie-lines for heptane + thiophene + tetraethylene glycol and cyclohexane + thiophene + tetraethylene glycol ternary mixtures at 298.15–313.15 K under a pressure of 83.4 ± 1 kPa. The experimental data were obtained by the cloud point method. Type 1 phase behavior is observed for the systems. The observed behavior was interpreted based on the type and nature of the interactions between the components. The capability of tetraethylene glycol in extractive desulfurization of thiophene from liquid fuel is evaluated by determining the solute distribution coefficient and selectivity. The high values of the selectivity show that tetraethylene glycol is a good candidate for this purpose. The investigation of the effect of temperature on the area of the biphasic region and distribution ratios shows that the extraction process can be performed at room temperature. The experimental data were successfully correlated with the NRTL model. The reliability of the correlation results was checked by using a Graphical User Interface (GUI) for the representation of Gibbs energy of mixing (GM). The root mean square deviation (RMSD), a measure of the precision of the correlations, ranges from 0.0022 to 0.0040.

The drying of flexible plastic waste is a current industrial problem in the plastic recycling sector. The thermal drying of plastic flakes is considered the most expensive and the most energy-consuming step in the recycling chain, which represents an environmental issue. This process is already present on the industrial scale but not well described in the literature. A better understanding of this process for this material will lead to the design of environmentally efficient dryers with an improved performance. The objective of this research was to investigate the behavior of flexible plastic in a convective drying process at a laboratory scale. The focus was to study the factors affecting this process such as velocity, moisture, size and thickness of the plastic flakes in both fixed and fluidized bed systems and to develop a mathematical model for predicting the drying rate considering heat and mass transfer of convective drying. Three models were investigated: the first one was based on a kinetic correlation of the drying, and the second and third models were based on heat and mass transfer mechanisms, respectively. It was found that heat transfer was the predominant mechanism of this process, and the prediction of the drying was possible. The mass transfer model, on the other hand, did not give good results. Amongst five semi-empirical drying kinetic equations, three equations (Wang and Singh, logarithmic and 3rd-degree polynomial) provided the best prediction for both fixed and fluidized bed systems.

Problema parcial Cantidad de Movimiento

Transferencia de energía, convocatoria junio 2023

This paper studied the thermal behaviour of Heet tobacco analysing the functional groups generated in the process of decomposition in inert and oxidative atmosphere. The effect of three zeolites, ZSM5, USY, and Beta, and two silicates, SBA-15 and Silica Fumed (SF) in the compounds of decomposition has been studied. The stages of decomposition of the tobacco (TGA) and the evolution of the functional groups with temperature (FTIR) have been analyzed. All additives produce significant changes in the volatiles generated under both atmospheres, being Beta zeolite and especially SBA-15 the materials more markedly reducing the yields of methylene, alcohols, CO, CO2 and carbonyl compounds, during the pyrolysis of Heet tobacco under nitrogen and air atmospheres. This effect may contribute efficiently to further reduce the toxicity of the Heet HNB tobacco.

Problema Bal de Materia enero 2023

In the present work, the NRTL model has been analyzed to obtain a good representation of the different ternary liquid-liquid equilibria that this thermodynamic model can reproduce satisfactorily. To do that, the main characteristics of different possible binary subsystems, ternary binodal curves (location in the composition diagram, size, tie-lines orientation, and plait point location), and LLLE tie triangles have been evaluated. With more than two hundred systems studied, the different behaviors have been parametrized to create, as the main objective of the present work, a database and a graphical user interface associated (ParamIni_LL_NRTL, Labarta et al. 2022. RUA: http://hdl.handle.net/10045/130017). This resource (publicly available for teaching and research uses) allows, given a set of ternary experimental LLE data to obtain by comparison with the elements of the database, a consistent set of initial NRTL parameters (taui,j, alfai,j) to start the corresponding correlation data procedure with enough guarantees.

Walnut shells can be used as fuels in power plants directly or as biochars obtained by pyrolysis or torrefaction. They are an example of clean waste biomass which shows a low ash content and a high Net Calorific Value, making them excellent for energy recovery in industrial and non-industrial applications, such as in bakeries, restaurants, and homes. Their main inconvenience is their low bulk density. Densification is a possible solution that reduces the costs of transportation, handling, and storage. In this work, after the characterization of the walnut shells, briquettes were obtained using a hydraulic piston press briquette machine under different conditions to find the best quality without the need for previous grinding for pelletizing. This method features easy operation and maintenance, and the briquette shape could be adapted as desired. The quality of the briquettes was measured through their density and durability. After fixing a compaction pressure to obtain acceptable briquettes, the factors affecting their quality were studied: operating temperature, moisture content, and the presence of small amounts of walnuts. Good quality briquettes were obtained with a compaction pressure of 66 MPa, with densities around 1040 kg/m3, and durabilities higher than 94% when the process was carried at 140 °C. The greatest increase in durability was observed between briquettes obtained at room temperature and those obtained at 80 °C. The presence of small amounts of walnuts, common after the shelling process, improved the durability. Although water is necessary, briquettes obtained from biomass with only 1% of moisture showed better durabilities. Therefore, walnut shells are suitable for obtaining good quality briquettes according to the specifications of solid biofuels established in the standards, without the need for any pretreatment.

This paper aims to provide an improvement in the modeling of supply chain designs by incorporating correlated uncertainty among multiple parameters, resulting in a more resilient design. A new methodology to generate forecasts for historically correlated time series, regardless of their underlying probability distributions, is presented and applied to generate scenarios for energy and carbon prices, which historically proved to be correlated. These scenarios are then used in a stochastic computation to obtain a three-echelon supply chain design in Europe maximizing the economic performance. The emissions were monetarized through the incorporation of the European Union cap-and-trade emissions trading system into the model. The social impact of the supply chain network is measured in terms of the direct, indirect and induced jobs it creates, which are proportional to the economic performance. By combining the developed methodology with data mining algorithms, a reduction in the number of required scenarios by more than 90% was achieved. The numerical case study moreover shows that the stochastic design ensures an average reduction of emissions by more than 3 ktons compared to the use of a deterministic approach. In comparison, the computation of a stochastic supply chain design without parameter correlation takes 5 times longer.

The management and final disposal of agro-industrial wastes are one of the main environmental problems. Due to the presence of silica in some agricultural by-products, it is possible to convert waste into materials with advanced properties. This contribution was aimed to extract and characterize silica materials from various feedstocks including sugarcane bagasse (SCB), corn stalk (CS), and rice husk (RH). Silica yields of 17.91%, 9.39%, and 3.25% were obtained for RH, CS, and SCB. On the other hand, the textural properties show that the siliceous materials exhibited mesoporous structures, with high silica composition in the materials due to the formation of crystalline SiO2 for SCB and CS and amorphous for RH. XPS spectra demonstrate the presence of Si4+ species in RH, and Si3+/Si4+ tetrahedra in SCB and CS.

Post-consumer low density polyethylene samples were analysed for PAHs, PCDD/Fs and dioxin-like PCBs content. Subsequently, various treatments were applied to determine a process capable of decontaminating the plastic samples: extraction with polyethylene glycol at different temperatures with and without agitation; extraction using subcritical and hot water at different temperatures in a basic medium; compound degradation by ultraviolet radiation; and compound degradation by advanced oxidation processes using H2O2. The most effective treatment was extraction with polyethylene glycol (agitated) at 120 °C, reducing contamination by 89%, 85% and 95% of PAHs, PCDD/Fs, and dioxin-like PCBs, respectively. The least effective treatments (subcritical and hot water), maximum reductions of 47% and 19% of PAHs were obtained for the temperatures of 160 °C and 90 °C. UV oxidation increased the toxic equivalency of the samples (calculated using the toxicity equivalency factors) by up to 1400%, through the co-formation of the most toxic congeners, e.g., the non-ortho PCBs.

With the rapid development of the global electronics industry, waste printed circuit boards (WPCBs) has become one of the world's fastest growing waste streams. Exploring an environmentally sound treatment for this abundant and multi-component waste is critical to its sustainable development. This study has been aimed to cover thermochemical conversion of WPCBs (combustion, pyrolysis, gasification and hydrothermal process), focusing on thermal behavior, reaction kinetics, pollutant evolution and corresponding controlling strategies, with the aim of promoting circular economic development and building a sustainable future for the electronics industry.

Transferencia de materia, fenómenos de transporte

Balance materia julio 2023