Browsing by Author "Molina, Paulo"

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    Applicability of Paper and Pulp Industry Waste for Manufacturing Mycelium-Based Materials for Thermoacoustic Insulation
    (2024) Munoz, Hugo; Molina, Paulo; Urzua-Parra, Ignacio A.; Vasco, Diego A.; Walczak, Magdalena; Rodriguez-Grau, Gonzalo; Chateau, Francisco; Sancy, Mamie
    Cellulose and paper produce significant waste such as ash, activated sludge, and sludge from the pulp and paper industry. Depending on the raw material, legislation, and subprocesses, these sludges contain around 30-50% organic matter, mainly composed of less than 0.02 mm cellulose fibers and hemicellulose and lignin. This work used sludge from the pulp and paper industry as a substrate for manufacturing mycelium-based biomaterials using the white rot fungus Trametes versicolor. Chemical and surface analyses revealed the formation of new materials. Acoustic impedance analyses revealed that these materials have a noise reduction coefficient and sound absorption average comparable to extruded polystyrene and polyurethane. In addition, the material's thermal conductivity was near that of sheep wool. Therefore, the biomaterials fabricated using sludge and Trametes versicolor have the potential to be a game-changer in the industry as promising thermoacoustic insulators.
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    Electrochemical analysis of carbon steel embedded in mortars with pretreated copper tailings as supplementary cementitious material
    (2024) Sepulveda-Vasquez, Carlos; Carrasco-Astudillo, Nicolas; Munoz, Lisa; Molina, Paulo; Ringuede, Armelle; Guerra, Carolina; Sancy, Mamie
    The cement industry, responsible for 8% of global greenhouse gas emissions, necessitates developing sustainable materials to replace cement partially. This investigation examined the feasibility of using copper tailings, a byproduct of mining, as alternative materials for cement within mortars and reinforced mortars (0-15 wt%). The microstructural composition of the tailings was analyzed using scanning electron microscopy and X-ray diffraction. The corrosion resistance of mortars reinforced with copper tailings was elucidated through opencircuit potential measurements and electrochemical impedance spectroscopy. The results showed that incorporating 5 and 10 wt% of sieved copper tailings improved the mechanical strength and significantly enhanced the electrochemical stability, as indicated by more noble open-circuit potential values. Specifically, the sieved tailings played a crucial role in forming a more stable oxide film, which was confirmed by higher impedance values, suggesting a reduced corrosion rate. In contrast, mortars with 5 wt% of milled tailings exhibited properties like those of the control group. This electrochemical understanding highlights the potential of processed copper tailings in mitigating the environmental impact of cement production and enhancing the durability of cementitious composites.
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    Electrochemical dynamic sensing of hydrogen peroxide in the presence of microorganisms
    (2019) Gulppi, Miguel; Muñoz, Lisa; Vejar, Nelson; Blarney, Jenny M.; González, Evelyn; Azócar, Manuel; Sancy, Mamié; Molina, Paulo; Zagal, José H.; Paez, Maritza
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    On the validation and applicability of multiphysics models for hydrogen SOFC
    (2024) Diaz, Brayn; Celentano, Diego; Molina, Paulo; Sancy, Mamie; Troncoso, Loreto; Walczak, Magdalena
    Solid oxide fuel cells (SOFC) are a viable alternative for environmentally-friendly conversion of hydrogen into energy and multiphysics simulation can be used to diminish the experimental effort to improve their efficiency. However, an appropriate model of the involved processes and their parameters must be chosen. This paper studies the effects of choice between Maxwell-Stefan and Fick's law models, and uncertainty of electrode ionic conductivity sigma(ion) ion and anodic reference exchange current density i(0,ref,f), on cell performance as implemented in the COMSOL Multiphysics (R) software. In the case of Maxwell-Stefan, peak average power output increased by 21.9% as sigma(ion) varies from 10(-3) to 10(-1) S/cm, while the model based on Fick's law shows an increase of 55.2%. The Maxwell-Stefan model exhibits an increase in peak power of 6% as i(0,ref,f) ranges from 0.4 to 0.8 A/cm(2), and the Fick's law model an increase of 8.2%. The dependence of the Maxwell-Stefan model on sigma(ion) is characterized as logarithmic in the studied range. The Maxwell-Stefan model is deemed preferable because its lower sensitivity to the studied parameters helps mitigate uncertainty. It is concluded that despite its limitations, multiphysics modeling is a useful tool for directing research on SOFC materials owing to its descriptive potential.