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Maisterra Udi, Maitane

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https://academica-e.unavarra.es/handle/2454/49487

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Maisterra Udi

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Maitane

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InaMat2. Instituto de Investigación en Materiales Avanzados y Matemáticas

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0000-0002-0181-1601

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751802

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811481

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  • Thumbnail Image
    PublicationOpen Access
    Extraction of phenolic compounds from populus salicaceae bark
    (MDPI, 2022) Autor, Elsa; Cornejo Ibergallartu, Alfonso; Bimbela Serrano, Fernando; Maisterra Udi, Maitane; Gandía Pascual, Luis; Martínez Merino, Víctor; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Gobierno de Navarra / Nafarroako Gobernua; Universidad Pública de Navarra / Nafarroako Unibertsitate
    Lignocellulosic residues have the potential for obtaining high value-added products that could be better valorized if biorefinery strategies are adopted. The debarking of short-rotation crops yields important amounts of residues that are currently underexploited as low-grade fuel and could be a renewable source of phenolic compounds and other important phytochemicals. The isolation of these compounds can be carried out by different methods, but for attaining an integral valorization of barks, a preliminary extraction step for phytochemicals should be included. Using optimized extraction methods based on Soxhlet extraction can be effective for the isolation of phenolic compounds with antioxidant properties. In this study, poplar bark (Populus Salicaceae) was used to obtain a series of extracts using five different solvents in a sequential extraction of 24 h each in a Soxhlet extractor. Selected solvents were put in contact with the bark sample raffinate following an increasing order of polarity: n-hexane, dichloromethane, ethyl acetate, methanol, and water. The oily residues of the extracts obtained after each extraction were further subjected to flash chromatography, and the fractions obtained were characterized by gas chromatography coupled with mass spectrometry (GC–MS). The total phenolic content (TPC) was determined using the Folin–Ciocalteu method, and the antioxidant activity (AOA) of the samples was evaluated in their reaction with the free radical 2,2-Diphenyl-picrylhydrazyl (DPPH method). Polar solvents allowed for higher individual extraction yields, with overall extraction yields at around 23% (dry, ash-free basis). Different compounds were identified, including hydrolyzable tannins, phenolic monomers such as catechol and vanillin, pentoses and hexoses, and other organic compounds such as long-chain alkanes, alcohols, and carboxylic acids, among others. An excellent correlation was found between TPC and antioxidant activity for the samples analyzed. The fractions obtained using methanol showed the highest phenolic content (608 g of gallic acid equivalent (GAE)/mg) and the greatest antioxidant activity.
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    PublicationOpen Access
    Obtención de compuestos químicos de interés a partir de residuos agroforestales
    (2024) Maisterra Udi, Maitane; Cornejo Ibergallartu, Alfonso; Ciencias; Zientziak; Universidad Pública de Navarra/Nafarroako Unibertsitate Publikoa
    La biomasa lignocelulósica es la mayor fuente renovable de compuestos orgánicos. En la presente Tesis Doctoral se abordan la valorización de dos tipos de residuos industriales de biomasa lignocelulósica. En primer lugar, se lleva a cabo la valorización de la fracción de lignina del serrín de Populus salicaceae (Populus sp.), comúnmente conocido como 'chopo'. Para ello, se utilizan dos estrategias diferentes. La primera consiste en el aislamiento de la lignina, para obtener ligninas técnicas, y su posterior despolimerización en medio básico, mediante hidrogenólisis o combinando ambas metodologías. La segunda estrategia consiste en el fraccionamiento catalítico, FC, directo de la biomasa, utilizando catalizadores de tipo sílice, o fraccionamiento catalítico reductivo, FCR, empleando catalizadores comerciales como Ru/C o sintetizados y caracterizados ad-hoc como el carburo de molibdeno soportado en carbón activo, de acuerdo con la estrategia ‘Lignin First’. Los resultados obtenidos en el FC y FCR del serrín en procesos en lote fueron muy superiores a los obtenidos mediante despolimerización de ligninas técnicas, con rendimientos muy próximos al máximo teórico. Se ensayó el FC y FCR en procesos en flujo continuo, y se estudió el efecto de las condiciones de operación en el rendimiento del fraccionamiento, en la integridad de la pulpa deslignificada y en el catalizador, obteniendo los mejores resultados con el catalizador β-Mo2C en lote, a 200 ºC durante 480 min con H2 con un rendimiento de 34% p/p a monómeros. En una segunda aproximación, se ha estudiado la valorización de la corteza de Populus salicaceae (Populus sp.). Para ello se han llevado a cabo diferentes extracciones mediante Soxhlet, utilizando disolventes con distintas polaridades. Los extractos fueron fraccionados mediante cromatografía en columna para disminuir su complejidad y facilitar la identificación de compuestos activos. Una vez obtenidos tanto los extractos como sus fracciones estos fueron estudiados mediante diferentes protocolos para la evaluación de su actividad antioxidante (método del radical libre DPPH), determinación del contenido fenólico total (CFT) con el método de Folin-Ciocalteu y el estudio de la actividad virucida y antiviral de dos diferentes virus, el virus de Chikungunya y el Herpes Simple Tipo 1. Se encontró una actividad virucida prometedora para una familia de extractos. Aunque no pudo identificarse el compuesto responsable de dicha actividad los resultados que se recogen en esta Memoria son altamente prometedores.
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    PublicationOpen Access
    Innovative flow-through reaction system for the sustainable production of phenolic monomers from lignocellulose catalyzed by supported Mo2C
    (Wiley, 2024) Maisterra Udi, Maitane; Atienza Martínez, María; Hablich Alvarracin, Karina Lissett; Moreira, Rui; Martínez Merino, Víctor; Gandía Pascual, Luis; Cornejo Ibergallartu, Alfonso; Bimbela Serrano, Fernando; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra - Nafarroako Unibertsitate Publikoa
    Molybdenum carbide supported on activated carbon (β-Mo2C/AC) has been tested as catalyst in the reductive catalytic fractionation (RCF) of lignocellulosic biomass both in batch and in Flow-Through (FT) reaction systems. High phenolic monomer yields (34 wt.%) and selectivity to monomers with reduced side alkyl chains (up to 80 wt.%) could be achieved in batch in the presence of hydrogen. FT-RCF were made with no hydrogen feed, thus via transfer hydrogenation from ethanol. Similar selectivity could be attained in FT-RCF using high catalyst/biomass ratios (0.6) and high molybdenum loading (35 wt.%) in the catalyst, although selectivity decreased with lower catalyst/biomass ratios or molybdenum contents. Regardless of these parameters, high delignification of the lignocellulosic biomass and similar monomer yields were observed in the FT mode (13-15 wt.%) while preserving the holocellulose fractions in the delignified pulp. FT-RCF system outperforms the batch reaction mode in the absence of hydrogen, both in terms of activity and selectivity to reduced monomers that is attributed to the two-step non-equilibrium processes and the removal of diffusional limitations that occur in the FT mode. Even though some molybdenum leaching was detected, the catalytic performance could be maintained with negligible loss of activity or selectivity for 15 consecutive runs.
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    PublicationOpen Access
    Production of aromatic compounds by catalytic depolymerization of technical and downstream biorefinery lignins
    (MDPI, 2020) Cornejo Ibergallartu, Alfonso; Bimbela Serrano, Fernando; Moreira, Rui; Hablich Alvarracin, Karina Lissett; García Yoldi, Íñigo; Maisterra Udi, Maitane; Portugal , António; Gandía Pascual, Luis; Martínez Merino, Víctor; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Gobierno de Navarra / Nafarroako Gobernua, PC036-037 Biovalorización; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
    Lignocellulosic materials are promising alternatives to non-renewable fossil sources when producing aromatic compounds. Lignins from Populus salicaceae., Pinus radiata and Pinus pinaster from industrial wastes and biorefinery effluents were isolated and characterized. Lignin was depolymerized using homogenous (NaOH) and heterogeneous (Ni-, Cu-or Ni-Cu-hydrotalcites) base catalysis and catalytic hydrogenolysis using Ru/C. When homogeneous base catalyzed depolymerization (BCD) and Ru/C hydrogenolysis were combined on poplar lignin, the aromatics amount was ca. 11 wt.%. Monomer distributions changed depending on the feedstock and the reaction conditions. Aqueous NaOH produced cleavage of the alkyl side chain that was preserved when using modified hydrotalcite catalysts or Ru/C-catalyzed hydrogenolysis in ethanol. Depolymerization using hydrotalcite catalysts in ethanol produced monomers bearing carbonyl groups on the alkyl side chain. The analysis of the reaction mixtures was done by size exclusion chromatography (SEC) and diffusion ordered nuclear magnetic resonance spectroscopy (DOSY NMR).31P NMR and heteronuclear single quantum coherence spectroscopy (HSQC) were also used in this study. The content in poly-(hydroxy)-aromatic ethers in the reaction mixtures decreased upon thermal treatments in ethanol. It was concluded that thermo-solvolysis is key in lignin depolymerization, and that the synergistic effect of Ni and Cu provided monomers with oxidized alkyl side chains.
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    PublicationOpen Access
    The 3D-printing fabrication of multichannel silicone microreactors for catalytic applications
    (MDPI, 2023) Ibáñez de Garayo Quilchano, Alejandro; Imizcoz Aramburu, Mikel; Maisterra Udi, Maitane; Almazán, Fernando; Sanz Carrillo, Diego; Bimbela Serrano, Fernando; Cornejo Ibergallartu, Alfonso; Pellejero, Ismael; Gandía Pascual, Luis; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
    Microstructured reactors (MSRs) are especially indicated for highly demanding heterogeneous catalysis due to the small channel dimensions that minimize diffusional limitations and enhance mass and heat transport between the fluid and the catalyst. Herein, we present the fabrication protocol of the fused filament 3D printing of silicone monolithic microreactors based on a multichannel design. Microchannels of 200 to 800 µm in width and up to 20 mm in length were developed following the scaffold-removal procedure using acrylonitrile butadiene styrene (ABS) as the material for the 3D-printed scaffold fabrication, polydimethylsiloxane (PDMS) as the building material, and acetone as the ABS removing agent. The main printing parameters such as temperature and printing velocity were optimized in order to minimize the bridging effect and filament collapsing and intercrossing. Heterogeneous catalysts were incorporated into the microchannel walls during fabrication, thus avoiding further post-processing steps. The nanoparticulated catalyst was deposited on ABS scaffolds through dip coating and transferred to the microchannel walls during the PDMS pouring step and subsequent scaffold removal. Two different designs of the silicone monolithic microreactors were tested for four catalytic applications, namely liquid-phase 2-nitrophenol photohydrogenation and methylene blue photodegradation in aqueous media, lignin depolymerization in ethanol, and gas-phase CO2 hydrogenation, in order to investigate the microreactor performance under different reaction conditions (temperature and solvent) and establish the possible range of applications.