Browsing by Author "Juárez, Juliana M."

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2,5-dimethylfuran production by biomass via 5-hydroxymethylfurfural over bimetallic catalyst
(2020) Ledesma, Brenda C.; Juárez, Juliana M.; Mazzario, Jaime; Beltramone, Andrea R.; Domine, Marcelo
En el presente trabajo se estudió la transformación catalítica de 5-hidroximetilfurfural (HMF) para producir 2,5-dimetilfurano (DMF) sobre catalizadores bimetálicos (PtIr) y monometálicos (Pt) soportados en materiales mesoporosos CMK-3 y SBA-15. Se estudiaron también la temperatura y presión óptimas para lograr la máxima producción de 2,5 DMF. Los catalizadores se caracterizaron ampliamente por XRD, isotermas de N2, XPS, TPR, TEM y NH3-TPD. En el estudio se observó que las partículas metálicas estaban bien reducidas y muy dispersas en la superficie del soporte debido a la gran área superficial y la distribución de poros del mismo. Los sitios de PtIr fueron muy activos y selectivos hacia la formación del 2,5 DMF. El catalizador PtIr-CMK- 3 mostró una excelente actividad, selectividad y estabilidad para ser aplicado en este proceso.
Bimetallic platinum/iridium modified mesoporous catalysts applied in the hydrogenation of hmf
(2020) Juárez, Juliana M.; Beltramone, Andrea R.; Ledesma, Brenda C.
The catalytic transformation of 5-hydroxymethylfurfural (HMF) to produce 2,5-dimethylfuran (DMF) was studied over bimetallic (PtIr) and monometallic (Pt) catalysts supported on CMK-3 and SBA-15 mesoporous materials. The optimum temperature and pressure for the maximum production of DMF were 120° and 15 atm. Increases in temperature and pressure decreased the selectivity to DMF. The catalysts were broadly characterized by XRD, N2-isotherms, XPS, TPR, TEM and NH3-TPD. It was found that the metal particles were well reduced and highly dispersed on the surface of the support of large surface area and narrow pore distribution. The PtIr alloy species active sites were very active and selective towards the formation of the desired DMF. PtIr-CMK-3 showed an excellent activity, selectivity and stability to be applied in this process.
Controlled drug release system: MCF-Chlorambucil mesoporous foam
(2022) Juárez, Juliana M.; Cussa, Jorgelina; Anunziata, Oscar Alfredo; Goméz Costa, Marcos Bruno
Mesostructured cellular foam (MCF) is a promising material for drug delivery systems due to its high biocompatibi0lity, biodegradability, and low toxicity. Its properties include a large surface area, uniform large pore. In this work, the MCF mesoporous foam was successfully synthesized for its application in drug nanocarriers, specifically Chlorambucil, obtaining the MCF-CLB composite. The synthesis of the mesoporous material and the process of incorporation of Chlorambucil in the pores of the MCF were successful as shown in the XRD, UV Vis Ref. Difusa, TEM analysis and analysis of textural properties. The release of the drug was conducted by simulating the physiological conditions to reproduce the conditions of the organism. The mechanism of drug release from the MCF-CLB host was evaluated. Different mathematical models were used to adjust the experimental data, the best model describing the phenomenon under study over the entire period is the Weibull model. The auspicious results we attained for the release of the drug using the new material, the main advantage of this release is that the rate of release is fast at the beginning and then gradually decreases until 24 h practically all the drug contained in the carrier is released (>95%).
Direct synthesis and characterization of mesoporous carbon CMK-3 modified with zirconia applied in energy storage
(2020) Venosta, Lisandro F.; Gómez Costa, Marcos B.; Juárez, Juliana M.; Anunziata, Oscar A.
In this work, we report the synthesis and characterization of the nanostructured carbon material (CMK- 3) modified with zirconium oxide synthesized by a new direct synthesis technique. The aim of this new synthesis method is to avoid the use of inorganic siliceous template (SBA-15), which leads to a shorter and cheaper way to obtain mesoporous carbon, and at the same time incorporate into the framework Zirconium atoms. Zirconium oxide dispersed in carbon materials (Zr-CMK-3) were successfully synthesized and characterized by X-ray diffraction, textural properties, UV-Vis-DRS, XPS, and transmission electron microscopy analysis. This material is promising in the application of hydrogen adsorption for energy storage. Zr-CMK-3 material significantly improved H2 storage behavior (4.6% by weight at 77 K and 10 bar) compared to CMK-3 support. The synthesized material is promising in the absorption of hydrogen by weak bonding forces (physisorption). A hydrogen adsorption mechanism was proposed and the role of the Zr+4 cation in hydrogen absorption was discussed. The activity of the samples to the adsorption of hydrogen molecules is attributed to the improved dispersion of the zirconium oxide, as well as the appropriate use of support, which can probably disperse the zirconium on its large surface area, allowing a great dispersion of the zirconium. The Zr+4 cation is an active species to absorb and store hydrogen through a physisorption process and the carbon plays an important role in the dispersion and size of metal particles. A hydrogen storage mechanism on the active surface of the ZrO2 clusters was proposed. First layer of hydrogen molecules can react with the metal cation through a dihydrogen complex (Kubas interaction) [1]. The second layer of hydrogen molecules adsorbed around the metal oxide clusters is due to dipole-like interactions, this is because the metal particle induces dipole forces on the hydrogen molecule. The other layers could also interact by dipole forces; however, the interaction force decreases as the distance to the surface increases. The interaction of the induced dipole in a second layer adsorbs more hydrogen molecules because the strong interaction of the metal particles takes up dipole-induced forces on the hydrogen molecules. The upper layers could interact with the metal cation by dipole-induced bonding; however, the interaction force decreases as the distance to the surface increases. The procedure for this adsorption is still under investigation and optimization. The hydrogen storage behavior in Zr-CMK-3 can be optimized by controlling the size of the metal particles, the dispersion and the nature of the support.
Green hydrogen from catalytic ammonia decomposition
(2021) Gómez Costa, Marcos B.; Juárez, Juliana M.; Anunziata, Oscar A.
Ir/γ-alumina catalysts for decomposition of ammonia were prepared by Iridium ion exchange procedure, onto γ-alumina synthesized by sol-gel method. In order to determine the physical and chemical properties we used X ray diffraction (XRD) analysis, Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nuclear magnetic resonance (NMR-MAS). The samples displayed the characteristic band at 1620 cm-1 corresponds to a N-H bending of ammonia adsorbed on electron-acceptor sites, and the characterization by pyridine adsorption and desorption to determine the presence of Lewis acid sites, with absence of Brønsted sites, showing higher acid strength than commercial sample used as reference. The analysis of particle size and morphology reveal uniformity, with tendency to a spheroid aspect and smaller to 3 μm of diameter. The 27Al NMR-MAS test, allowed determining the tetrahedral and octahedral aluminum presence in both samples, where the higher proportion of octahedral Al in γ-alumina synthesized by us, is correlated toward the greater electron acceptor acid sites. The designed method was effective for Ir/γ-alumina catalysts synthesis. The surface area was 150 and 260 m2/g for the commercial sample and the alumina prepared by and us, and after the Ir incorporation (10-18% w/w in both samples), they surfaces were reduced approximately 5.4-8.8% and 4.3-7.2% respectively. XRD analyses show the absence of maximums at 28º and 34.7º 2 corresponding to iridium oxide, indicating a high efficiency of the reduction treatment, increasing the active sites for the specific reaction of ammonia decomposition. The distribution of the Ir crystallites determined by XRD and TEM indicated that, the samples prepared by ion exchange method produced smaller Iridium clusters than by impregnation procedure of alumina sample, with higher surface area and greater anchorage sites. According to preliminary catalytic tests, the Ir/γ-alumina catalysts prepared by a novel method showed higher activity to ammonia decomposition to N2 and green H2.
Hydrogen storage on a novel nanostructured carbón material modified with zirconia
(2021) Juárez, Juliana M.; Gómez Costa, Marcos B.; Anunziata, Oscar A.; Venosta, Lisandro F.
In this work, we report the synthesis and characterization of zirconium oxide supported in nanostructured carbon material synthesized by a new direct synthesis technique. The goal of this new method is to avoid the use of inorganic siliceous template (SBA-15), which leads to a shorter and cheaper way to obtain mesoporous carbon, and at the same time incorporate into the framework Zirconium atoms. The material with zirconium oxide (Zr-CMK-3) was successfully synthesized and characterized by Xray diffraction, SEM, RAMAN and textural properties, UV-Vis-DRS, X-ray photoelectron spectroscopy and transmission electron microscopy analyses. Zr-CMK-3 improved significantly the H2 storage behavior (4.6 wt% at 77 K and 10 bar) compared with CMK-3. The synthesized material is promising for hydrogen uptake by means of weak bonding (physisorption). The activity of the samples to the adsorption of hydrogen molecules is attributed to the improved dispersion of the zirconium oxide, as well as the appropriate use of support, which can probably disperse the zirconium on its large surface area, allowing a great dispersion of the zirconium. The Zr+4 cation is an active species to absorb and store hydrogen through a physisorption process and the carbon plays an important role in the dispersion and size of metal particles. A hydrogen storage mechanism on the active surface of the ZrO2 clusters was proposed. First layer of hydrogen molecules can react with the metal cation through a dihydrogen complex (Kubas interaction). The second layer of hydrogen molecules adsorbed around the metal oxide clusters is due to dipole-like interactions, this is because the metal particle induces dipole forces on the hydrogen molecule. The other layers could also interact by dipole forces; however, the interaction force decreases as the distance to the surface increases. The upper layers could interact with the metal cation by dipole-induced bonding; however, the interaction force decreases as the distance to the surface increases.
Influence of ti incorporation to mesoporous carbon structure for 2,5 dmf production by biomass
(2021) Beltramone, Andrea R.; Ledesma, Brenda C.; Juárez, Juliana M.
Several metal an bimettallics catalysts were prepared in order to evaluate performance to produce 2,5- dimethylfuran (2,5-DMF) trough hydrogenolysis of 5-(hydroxymethyl) furfural (5-HMF). Detailed physico-chemical characterisation was done in order to understand structure-activity correlation. Through a series of experiments and comparison, the synergistic effect among Pt, Ir, and Ti was investigated. The results revealed that the titanium contained in the ordered mesoporous carbon promotes a synergistic effect between Pt-Ir and Ti; that plays an important role in improving selectivity to DMF for PtIr / TiC bimetallic catalysts
Mesoporous carbon cmk-3 modified with zirconia developed by direct synthesis technique applied in energy storage
(2021) Gómez Costa, Marcos B.; Juárez, Juliana M.; Venosta, Lisandro F.; Anunziata, Oscar A.
Nanostructured carbon material (CMK-3) modified with zirconium oxide was synthesized by a new direct synthesis technique. Zirconium oxide dispersed in carbon materials (Zr-CMK-3) were characterized by X-ray diffraction, textural properties, UV-Vis-DRS, XPS, and transmission electron microscopy analysis. The goal of this new synthesis method is to avoid the use of inorganic siliceous template (SBA-15), which leads to a shorter and cheaper way to obtain mesoporous carbon, and at the same time incorporate into the framework Zirconium atoms. Zr-CMK-3 material significantly improved H2 storage behavior (4.6% by weight at 77 K and 10 bar) compared to CMK-3 support. The synthesized material is promising in the absorption of hydrogen by weak bonding forces (physisorption). The activity of the samples to the adsorption of hydrogen molecules is attributed to the improved dispersion of the zirconium oxide, as well as the appropriate use of support, which can probably disperse the zirconium on its large surface area, allowing a great dispersion of the zirconium. The Zr+4 cation is an active species to absorb and store hydrogen through a physisorption process and the carbon plays an important role in the dispersion and size of metal particles. A hydrogen storage mechanism on the active surface of the ZrO2 clusters was proposed. First layer of hydrogen molecules can react with the metal cation through a dihydrogen complex (Kubas interaction). The second layer of hydrogen molecules adsorbed around the metal oxide clusters is due to dipole-like interactions, this is because the metal particle induces dipole forces on the hydrogen molecule. The other layers could also interact by dipole forces; however, the interaction force decreases as the distance to the surface increases. The upper layers could interact with the metal cation by dipole-induced bonding; however, the interaction force decreases as the distance to the surface increases.
New method for Ccmk-3 synthesis modified with zr applied in h2 storage
(2021) Juárez, Juliana M.; Gómez Costa, Marcos B.; Venosta, Lisandro F.; Anunziata, Oscar A.
In this work we develop a novel direct synthesis method of modified CMK-3 with zirconium oxide. This modification occurs during the synthesis process. Our assessment includes a one-step synthesis of nanostructured mesoporous carbon modified with zirconium oxide, the characterization of the resulting material by XRD, N2 adsorption, XPS, UV-Vis, TEM, SEM and Raman. We show the enhancement of the storage capacity of the composite material, compared to bare CMK-3.
Novedoso método de síntesis del carbón mesoporoso cmk-3 modificado con circonio y su aplicación en almacenamiento de hidrógeno
(2021) Gómez Costa, Marcos B.; Juárez, Juliana M.; Anunziata, Oscar A.; Venosta, Lisandro F.
En este trabajo, informamos la síntesis y caracterización del material de carbono nanoestructurado (CMK-3) modificado con óxido de circonio sintetizado por una nueva técnica de síntesis directa. Este material es prometedor en la aplicación de adsorción de hidrógeno para el almacenamiento de energía. Los materiales con óxido de circonio (Zr-CMK-3) se sintetizaron con éxito y se caracterizaron por difracción de rayos X, propiedades texturales, XPS y análisis de microscopía electrónica de transmisión. El material Zr-CMK-3 mejoró significativamente el comportamiento de almacenamiento de H2 (4,6% en peso a 77 K y 10 bar) en comparación con el soporte CMK-3. El material sintetizado es prometedor en la absorción de hidrógeno por fuerzas de enlace débiles (fisisorción). Se propuso un mecanismo de adsorción de hidrógeno y se discutió el rol de catión Zr+4 en la absorción de hidrógeno.
Novel omc by nanocasting strategy for hydrogen adsorption
(2021) Juárez, Juliana M.; Gómez Costa, Marcos B.; Anunziata, Oscar A.
A silica material of the SBA-15 type with ultra-large pores (20 nm) was synthesized by the sol-gel method. This silica mesoporous material was impregnated twice consecutively with an acid solution of sucrose and the organic material carbonised inside the mesopores. After dissolution of the silica framework, an ordered mesoporous carbon (OMC) with regular mesopores with mean diameter in the range of 6 nm. The specific surface area of the carbon was increased by increasing filling of the silica pores with the organic material, from 350 m2/g to 950 m2/g. The novel OMC material was successfully synthesized and characterized by X-ray diffraction, textural properties, SEM and transmission electron microscopy analyses. This novel OMC improved significantly the H2 storage behaviour (2.62 wt% at 77 K and 10 bar) compared with a similar CMK-3 (2.18 wt% at 77K and 10 bar). The synthesized material is promising for hydrogen uptake by means of weak bonding (physisorption).
Preparation, characterization and mathematical modeling of keterolac release conteined in lpsba-15 host
(2021) Cussa, Jorgelina; Juárez, Juliana M.; Gómez Costa, Marcos B.; Anunziata, Oscar A.
Drug-controlled release systems can keep the level of drugs in precise doses in the body above the optimal level and with low toxicity. We propose the LP-SBA-15 nanomaterial as a promising new host for drug delivery systems because of its high biocompatibility, in vivo biodegradability, and low toxicity. Ketorolac-LP-SBA-15 was prepared and characterized by XRD, FTIR, UV-Vis DRS, TEM, and texture analysis, determining the adsorption capacity and its release, achieving the required therapeutic efficacy. The host shows ordered mesoporous nanochannels with a diameter of 11-12 nm, maintaining the structure with the incorporation of Keto. The mechanism of drug release the LP-SBA-15 host was evaluated. Different mathematical models were used to adjust the experimental data, being the Ritger-Peppas model followed by the Weibull model the best ones. In this work, we show a promising drug storage material for effective encapsulation and controlled release of KETO, achieving the required therapeutic efficacy. Studies indicate that KETO was adsorbed on the channel surface of LP-SBA-15 without affecting the structure or chemical composition of KETO. Controlled drug delivery systems can achieve precise delivery at the time and place of destination, keeping the concentration of the drug at points in the body within the optimal range and below the toxicity threshold. The study also demonstrates the storage capacity and release properties of LPSBA- 15 containing KETO. The release of KETO contained in LP-SBA-15 can offer a significant improvement in the controlled release of the drug and the analgesic and anti-inflammatory effects, positively influenced, by the links formed between the host and drug molecules and by diffusion through the host porosity. The promising results we obtained for the release of the drug thoroughly using the new material, reaching a rapid initial release rate, and maintaining a constant rate afterward, allow us to maintain the concentration of the drug in the therapeutic efficacy range, applying it largely to the treatment of diseases that require a rapid response.
Síntesis directa del carbón mesoporoso ordenado cmk-3 modificado con circonio aplicado en almacenamiento de energía
(2020) Gómez Costa, Marcos B.; Juárez, Juliana M.; Anunziata, Oscar A.; Venosta, Lisandro F.
En este trabajo, informamos la síntesis y caracterización del material de carbono nanoestructurado (CMK-3) modificado con óxido de circonio sintetizado por una nueva técnica de síntesis directa. Este material es prometedor en la aplicación de adsorción de hidrógeno para el almacenamiento de energía. Los materiales con óxido de circonio (Zr-CMK-3) se sintetizaron con éxito y se caracterizaron por difracción de rayos X, propiedades texturales, UV-Vis-DRS, XPS y análisis de microscopía electrónica de transmisión. El material Zr-CMK-3 mejoró significativamente el comportamiento de almacenamiento de H2 (4,6% en peso a 77 K y 10 bar) en comparación con el soporte CMK-3. El material sintetizado es prometedor en la absorción de hidrógeno por fuerzas de enlace débiles (fisisorción). Se propuso un mecanismo de adsorción de hidrógeno y se discutió el rol de catión Zr+4 en la absorción de hidrógeno.
Síntesis, caracterización y aplicación del nanomaterial lp-sba-15 en la liberación controlada de ketorolac trometamina
(2020) Juárez, Juliana M.; Gómez Costa, Marcos B.; Cussa, Jorgelina
Los sistemas controlados de administración de fármacos pueden mantener la concentración de medicamentos en los sitios exactos del cuerpo dentro del rango óptimo y por debajo del umbral de toxicidad, mejorando la eficacia terapéutica y reduciendo la toxicidad. El material LP-SBA-15 es un nuevo huésped prometedor para los sistemas de administración de fármacos debido a su alta biocompatibilidad, biodegradabilidad in vivo y baja toxicidad. Se sintetizó el composite ketorolac-trometamina/LP-SBA-15. La síntesis del material y la carga de ketorolac-trometamina en los poros LP-SBA-15 fue exitosa, como lo demuestran los análisis XRD, FTIR, TGA, TEM y análisis morfologicos. Obtuvimos resultados prometedores para la liberación controlada de fármacos utilizando el nuevo material. La aplicación de estos materiales en la liberación de KETO es innovadora, logrando una alta tasa de liberación inicial y luego manteniendo una liberación más lenta. Esto permite mantener la concentración del fármaco dentro del rango de eficacia terapéutica, siendo altamente aplicable para el tratamiento de enfermedades que necesitan una respuesta rápida.
Sistema de liberación controlada de fármacos: espuma mesoporosa MCF-clorambucilo
(2022) Juárez, Juliana M.; Cussa, Jorgelina; Anunziata, Oscar A.; Gómez Costa, Marcos Bruno
La espuma celular mesoestructurada (MCF) es un material prometedor para los sistemas de administración de fármacos dado a la alta biocompatibilidad, biodegradabilidad y baja toxicidad. Sus propiedades incluyen una gran área superficial, poro grande uniforme. En este trabajo, la espuma mesoporosa MCF fue sintetizada con éxito para su aplicación en nanotransportadores de fármacos, específicamente de Clorambucilo, obteniendo el composite MCF-CBL. La síntesis del material mesoporoso y el proceso de incorporación de Clorambucilo en los poros de la MCF fueron exitosos tal como se muestra en los análisis de XRD, FTIR, TEM y análisis de propiedades texturales. La liberación del fármaco se realizó simulando las condiciones fisiológicas para reproducir las condiciones del organismo. Se evaluó el mecanismo de liberación del fármaco en el hospedaje MCF-CLB. Se utilizaron diferentes modelos matemáticos para ajustar los datos experimentales, el mejor modelo que describe el fenómeno en estudio durante todo el período es el modelo de Weibull. Los resultados auspiciosos que obtuvimos para la liberación del fármaco utilizando el nuevo material, la principal ventaja de esta liberación es que la velocidad de liberación es rápida al inicio y luego disminuye gradualmente hasta que se liberan 24 h prácticamente todo el fármaco contenido en el portador. (> 95%).
Synthesis and characteristics of magnetite containing-cmk-3 and its application in hydrogen storage
(2020) Juárez, Juliana M.; Venosta, Lisandro F.; Gómez Costa, Marcos B.; Anunziata, Oscar A.
In this work, we report the synthesis and characterization of iron oxide nanoparticles (Magnetite) supported on CMK-3. The materials were characterized by XRD, SEM, TEM, XPS and magnetization studies. A large amount of the iron incorporated as iron oxide nanoparticles was in the magnetite phase. The incorporation of magnetite on the CMK-3 carbon surface significantly improved the hydrogen storage capacity (4.45 wt. % at 77 K and 10 bar) compared to the CMK-3 structure (2.20 wt% at 77 K and 10 bar). Magnetite nanoparticles play a key role in H2 adsorption.

Browsing by Author "Juárez, Juliana M."

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