Sonia Giraldo - Academia.edu (original) (raw)
Papers Vol. 9 núm. 17 enero-junio 2013 by Sonia Giraldo
"En este artículo se presenta el efecto de las sales inorgánicas MgSO4, NaCl y CaCO3 en la desinf... more "En este artículo se presenta el efecto de las sales inorgánicas MgSO4, NaCl y CaCO3 en la desinfección fotocatalítica del agua. Se usó TiO2-P25 como fotocatalizador y E. Coli como microorganismo contaminante. Las pruebas de desinfección se realizaron mediante la iluminación controlada de reactores batch cargados con agua contaminada, sales y TiO2. Los resultados de estas pruebas fueron usados para determinar los parámetros cinéticos de un modelo tipo Langmuir-Hinshelwood. Se encontró que las sales tienen una fuerte influencia sobre la inactivación fotocatalítica de E. Coli, y que cada sal y su concentración afectan la desinfección de forma diferente y en el siguiente orden: NaCl>CaCO3>>MgSO4. Adicionalmente, el valor de los parámetros calculados fue diferente para cada sal, evidenciando que las sales afectan el proceso por varios mecanismos relacionados con las interacciones ion-bacteria, ion-especie oxidante e ion-TiO2."
Papers by Sonia Giraldo
CT&F - Ciencia, Tecnología y Futuro
The aim of this work is to contribute to the current understanding on the role of the support’s a... more The aim of this work is to contribute to the current understanding on the role of the support’s acidic properties in the hydrogenating function of NiMo/-Al2O3 type catalysts during hydrodearomatization (HDA) and dibenzothiophene (DBT) type molecules desulfurization. NiMo/-Al2O3-B2O3 catalysts of different B2O3 (0, 2, 3, 6 and 8 wt.%) contents were prepared and tested in independent and simultaneous naphthalene (NP) HDA and DBT hydrodesulfurization (HDS) reactions. For HDA the catalytic activity as a function of the B2O3 content followed a volcano-shape trend, with a maximum around 3 wt.% of B2O3. In DBT desulfurization boron was found to have a positive effect in the development of the HYD route of desulfurization possibly due to an increase in total acidity. Conversely, the direct desulfurization route (DDS) was negatively affected by boron addition. The presence of NP during the HDS of DBT was found to have a significant effect in neither total HDS activity nor the HYD/DDS selec...
RESUMEN La catálisis heterogénea ha sido reconocida como una de las alternativas más promisorias ... more RESUMEN La catálisis heterogénea ha sido reconocida como una de las alternativas más promisorias para la solución integral a muchos de los problemas operacionales y ambientales que presenta la producción de biodiesel convencional. El propósito de esta investigación fue estudiar la actividad catalítica de diferentes catalizadores sólidos de naturaleza básica a partir de MgO, modificándolo mediante tratamientos hidrotérmicos e impregnación húmeda o seca de metales alcalinos, en la transesterificación de triacetina (molécula modelo) con etanol. Se analizó la influencia del: tratamiento hidrotérmico, tipo y cantidad de metal alcalino impregnado (Li, Cs, Rb) y la activación, sobre la basicidad y el comportamiento catalítico de los catalizadores. Las reacciones se realizaron en un sistema batch, con una relación molar etanol:triacetina de 10:1 y 3% en peso de catalizador. La reacción fue seguida por cromatografía de gases. La activación del MgO modificado con Li, Rb o Cs provocó un aument...
In this research, the behavior of calcium methoxide as catalyst for the production of biodiesel f... more In this research, the behavior of calcium methoxide as catalyst for the production of biodiesel from palm oil in a continuous system was studied. Initially, operating conditions such as CaO activation temperature (25°C), reaction temperature (60°C) and molar ratio methanol-oil (10)were established for a batch reactor. Then, the schematic diagram of the experimental setup and its implementation were described for a packed-bed laboratory scale reactor with continuous flow; for this system, yields of methyl esters of 20% with a residence time of 60 min were obtained. The use of co-solvent such as tert-Bbutanol and ethyl acetate in the continuous reaction system was also investigated, aiming to eliminate mass transfer artifacts between the phases and eventually increasing yields to methyl esters. The use of ethyl acetate as co-solvent increased methyl esters yields up to 31 %.
Revista U.D.C.A Actualidad & Divulgación Científica, 2011
INGENIERÍA Y COMPETITIVIDAD, 1970
En el presente trabajo se analizó el comportamiento del metóxido de calcio como catalizador para ... more En el presente trabajo se analizó el comportamiento del metóxido de calcio como catalizador para la producción de biodiesel a partir de aceite de palma. Inicialmente se establecieron condiciones de operación en un reactor por lotes, como temperatura de activación CaO (25°C), temperatura de reacción (60°C) y relación molar metanol/aceite (10). Se describió el montaje y puesta en marcha de un reactor de lecho fijo y flujo continuo a escala laboratorio; a las condiciones establecidas se obtuvieron rendimientos a métilesteres del 20% con un tiempo de residencia de 60 min. También se analizó el uso de cosolventes como el terbutanol y el acetato de etilo para eliminar las limitaciones de transferencia de masa entre las fases e incrementar los rendimientos a metil ésteres. Se encontró que el uso de etil acetato como cosolvente incrementó el rendimiento a metil esteres hasta el 31 %.
Gabriel (2017): Kinetic assessment of the simultaneous hydrodesulfurization of dibenzothiophene a... more Gabriel (2017): Kinetic assessment of the simultaneous hydrodesulfurization of dibenzothiophene and the hydrogenation of diverse polyaromatic structures. ChemRxiv. Preprint. The work presents a kinetic study of the simultaneous hydrodesulfurization of dibenzothiophene and hydrogenation of aromatics with different chemical structures. This kind of studies are seldom reported, since many authors deal almost exclusively with hydrodesulfurization. Furthermore, most of these authors employ power rate laws for kinetic modelling neglecting a rigorous analysis of the thermodynamic parameters of the reactions; namely, adsorption enthalpies and entropies. Considering this fact, we decided to base our kinetic modelling on a Langmuir-Hinshelwood-Hougen-Watson (LHHW) formalism testing the hypothesis of the existence of one or two different catalytic sites for hydrogenation and desulfurization. The consistency of the aforementioned thermodynamic parameters was assessed considering the criteria postulated by Boudart.Our results allowed concluding that a LHHW model considering two actives sites provides a statically satisfactory fitting of experimental data. In addition, it was possible to determine that inhibition effects of aromatics on hydrodesulfurization exist but depend to some extent on the molecular structure of the aromatic.On the other hand, this work also contributes by providing experimental values of adsorption constants of compounds reacting under hydrotreatment conditions which despite the significant advances in theoretical calculations are not yet available in open literature. File list (2) download file view on ChemRxiv Kinetic assessment of the simultaneous hydrodesulfurizati... (2.12 MiB) download file view on ChemRxiv Supporting information.pdf (740.53 KiB) Kinetic assessment of the simultaneous hydrodesulfurization of dibenzothiophene and the hydrogenation of diverse polyaromatic structures
Revista Ion, Investigación, Optimización y Nuevos procesos en Ingeniería, 2017
TiO 2-SiO 2 coatings on fabric samples were obtained by immersion of 9cm 2 of commercial polyeste... more TiO 2-SiO 2 coatings on fabric samples were obtained by immersion of 9cm 2 of commercial polyester in a TiO 2-SiO 2 suspension. This suspension was prepared by adding TiO 2 P25 to a silica matrix obtained from the hydrolysis of tetraethyl orthosilicate (TEOS). The aim of this work was to study the relationship between the immersion time of the fabric on the photocatalytic activity and stability of the coating against several cycles of use and washing. Obtained samples were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and infrared spectroscopy (FTIR-ATR). Evaluation of modified fabrics was performed by self-disinfection tests under 250W/m 2 of simulated sunlight using E. coli as model bacteria. In general, all modified fabrics (except that obtained at 2h immersion time) inactivated bacteria in less than 120min and its regrowth was prevented for at least 24h after the disinfection tests. It was determined that low immersion time (3-4h) lead to active and stable fabrics to 3 cycles of use and washing, whereas higher immersion times (12h) lead to more active but unstable fabrics.
Ingeniería y Ciencia, 2013
En este artículo se presenta el efecto de las sales inorgánicas MgSO4, NaCl y CaCO3 en la desinfe... more En este artículo se presenta el efecto de las sales inorgánicas MgSO4, NaCl y CaCO3 en la desinfección fotocatalítica del agua. Se usó TiO2-P25 como fotocatalizador y E. Coli como microorganismo contaminante. Las pruebas de desinfección se realizaron mediante la iluminación controlada de reactores batch cargados con agua contaminada, sales y TiO2. Los resultados de estas pruebas fueron usados para determinar los parámetros cinéticos de un modelo tipo Langmuir-Hinshelwood. Se encontró que las sales tienen una fuerte influencia sobre la inactivación fotocatalítica de E. Coli, y que cada sal y su concentración afectan la desinfección de forma diferente y en el siguiente orden: NaCl>CaCO3>>MgSO4. Adicionalmente, el valor de los parámetros calculados fue diferente para cada sal, evidenciando que las sales afectan el proceso por varios mecanismos relacionados con las interacciones ion-bacteria, ion-especie oxidante e ion-TiO2.
Revista Colombiana De Quimica, Apr 15, 2009
En este y en el próximo número de la Revista Colombiana de Química se publican, después de haber ... more En este y en el próximo número de la Revista Colombiana de Química se publican, después de haber sido sometidos a evaluación por pares, algunos de los trabajos presentados en dicho Simposio.
Ingenieria Y Universidad, Oct 27, 2010
Modificación de la relación zeolita-matriz en los catalizadores de FCC y su impacto en los rendim... more Modificación de la relación zeolita-matriz en los catalizadores de FCC y su impacto en los rendimientos y la calidad de los destilados medios * Modification of the Zeolite-Matrix Ratio in FCC Catalysts and its Impact on Yields and Quality of Middle Distillates ** Modificação da relação zeólita-matriz nos catalizadores de FCC e seu impacto nos rendimentos e qualidade dos destilados médios ***
Revista Colombiana De Quimica, 2008
Proyecto académico sin fines de lucro, desarrollado bajo la iniciativa de acceso abierto
Revista Ion, 2011
Aplicación de la descomposición del 2-propanol como técnica de caracterización ácido-base de cata... more Aplicación de la descomposición del 2-propanol como técnica de caracterización ácido-base de catalizadores CoMo para hidrotratamiento
We performed quantum mechanics calculations to elucidate the electronic behavior of Pd-Pt bimetal... more We performed quantum mechanics calculations to elucidate the electronic behavior of Pd-Pt bimetallic nanoparticles, using density functional theory, in response to particle size and stoichiometric composition. Using neutrally charged nanoparticles and the Bader charge analysis, we found that external Pd atoms were positively charged, which agrees with previous XPS observations of supported Pd-Pt nanoparticles. From the calculations, unsupported nanoparticles exhibit an electron transfer from Pd to Pt. This result supports the idea that Pd electron-deficient species are possibly responsible of the hydrogenating function of these catalysts, in the hydrodesulfurization of dibenzothiophene. Additionally, it was found that the particle size does not affect the electronic charge distribution and the stoichiometric composition is the factor that greatly influences this property in nanoparticles.
This article presents the effect of inorganic salts MgSO4, NaCl and CaCO3on the photocatalytic wa... more This article presents the effect of inorganic salts MgSO4, NaCl and CaCO3on the photocatalytic water disinfection. TiO2-P25 was used as a photocatalyst, and E. Coli was used as a contaminant. Disinfection tests were performed by controlling lighting of batch reactors loaded with contaminated water, salts and TiO2. The results of these tests were used to determine the kinetic parameters of a type Langmuir-Hinshelwood model. It was found that the salts have a strong influence on the photocatalytic inactivation of E. Coli and that each salt and its concentration affect disinfection differently in the following order: NaCl>CaCO3 >>MgSO4. Additionally, the value of the calculated parameters was different for each salt, showing that the salts affect the process by several mechanisms related to the ion-bacteria interactions, ion-oxidizing species and ion-TiO2.
The development of the hydrodesulfurization (HDS) of dibenzothiophene (DBT) type molecules by the... more The development of the hydrodesulfurization (HDS) of dibenzothiophene (DBT) type molecules by the hydrogenation (HYD) route over Pd-Pt/γ-Al2O3 catalysts was studied through the analysis of the reactivity of naphthalene over these materials. A series of Pd-Pt/γ-Al2O3 catalysts with different Pd/(Pd+Pt) molar ratios were prepared by the coimpregnation method, characterized by atomic absorption and nitrogen adsorption-desorption techniques and tested at temperatures between 503 and 543K and 5MPa. Results show a synergy in the selectivity to trans-decaline. It was concluded that the reaction mechanism of naphthalene over Pd-Pt/γ-Al2O3 bimetallic catalysts entails the roll-over of the Δ1,9-octalina over the catalytic surface. In this way, there exists a similarity with the reaction mechanism of DBT by the HYD route of HDS.
Fuel Processing Technology, 2015
DOI to the publisher's website. • The final author version and the galley proof are versions of t... more DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:
International Journal of Photoenergy, 2012
This paper reports the characterization and photoactivity of Ag-TiO2materials using different amo... more This paper reports the characterization and photoactivity of Ag-TiO2materials using different amounts of silver during the hydrothermal synthesis. Photocatalysts were characterized by means of TEM, XPS, XRD, DRS, and N2sorption isotherms to determine the textural properties. The photocatalyst's configuration was observed to be as anatase-brookite mixed phase particles with Ag partially oxidized aggregates on the TiO2surface, which increased visible light absorption of the material. Moreover, photoproduction of singlet oxygen was followed by EPR analysis under visible light irradiations following the formation of TEMPOL. Such photoproduction was totally decreased by using the singlet oxygen scavenger DABCO. Photocatalysts were tested towards the photocatalytic disinfection of water suing a solar light simulator and an interior-light irradiation setup. Results evidenced an increase in the photooxidative effect of TiO2, while dark processes evidenced that part of the inactivation p...
ABSTRACT Borated aluminas with different boria contents (2, 3, 5 and 8 wt.% B2O3) were prepared t... more ABSTRACT Borated aluminas with different boria contents (2, 3, 5 and 8 wt.% B2O3) were prepared to be used as supports for hydrotreating CoMo catalysts. The borated aluminas were characterized by proton affinity distributions (PAD) to obtain information about changes caused by boron introduction in the surface hydroxyl groups. The later being the sites by means of Mo and Co are anchored to the support. Two new peaks, which cannot be attributed to alumina hydroxyl groups, were found in the PAD profiles of borated aluminas. These two new peaks increased with increasing boria loading, even, in the PAD profile of the alumina with 8 wt.% B2O3 almost no other peaks were present. By comparing PAD profiles with FT-IR spectra of both the OH stretching (3900-3400 cm-1) and the skeletal (under 2000 cm-1) regions, it was possible to assign these new peaks to hydroxyls linked to trigonal and tetrahedral borated species, respectively. Thus, it could be inferred that boria OH groups progressively replaced alumina ones with increasing boria content forming a cover layer. Trigonal borated species were always predominant, however the relative population of tetrahedral species increased with increasing boria content.
Revista UDCA …, 2011
The present work aims to identify the influence of the chemical composition of water on bacterial... more The present work aims to identify the influence of the chemical composition of water on bacterial inactivation using a photocatalyst. Several simulated water matrixes were prepared using different concentrations of (HCO3)-, Cl-,(SO4) 2-,(HPO4) 2-on individual ...
"En este artículo se presenta el efecto de las sales inorgánicas MgSO4, NaCl y CaCO3 en la desinf... more "En este artículo se presenta el efecto de las sales inorgánicas MgSO4, NaCl y CaCO3 en la desinfección fotocatalítica del agua. Se usó TiO2-P25 como fotocatalizador y E. Coli como microorganismo contaminante. Las pruebas de desinfección se realizaron mediante la iluminación controlada de reactores batch cargados con agua contaminada, sales y TiO2. Los resultados de estas pruebas fueron usados para determinar los parámetros cinéticos de un modelo tipo Langmuir-Hinshelwood. Se encontró que las sales tienen una fuerte influencia sobre la inactivación fotocatalítica de E. Coli, y que cada sal y su concentración afectan la desinfección de forma diferente y en el siguiente orden: NaCl>CaCO3>>MgSO4. Adicionalmente, el valor de los parámetros calculados fue diferente para cada sal, evidenciando que las sales afectan el proceso por varios mecanismos relacionados con las interacciones ion-bacteria, ion-especie oxidante e ion-TiO2."
CT&F - Ciencia, Tecnología y Futuro
The aim of this work is to contribute to the current understanding on the role of the support’s a... more The aim of this work is to contribute to the current understanding on the role of the support’s acidic properties in the hydrogenating function of NiMo/-Al2O3 type catalysts during hydrodearomatization (HDA) and dibenzothiophene (DBT) type molecules desulfurization. NiMo/-Al2O3-B2O3 catalysts of different B2O3 (0, 2, 3, 6 and 8 wt.%) contents were prepared and tested in independent and simultaneous naphthalene (NP) HDA and DBT hydrodesulfurization (HDS) reactions. For HDA the catalytic activity as a function of the B2O3 content followed a volcano-shape trend, with a maximum around 3 wt.% of B2O3. In DBT desulfurization boron was found to have a positive effect in the development of the HYD route of desulfurization possibly due to an increase in total acidity. Conversely, the direct desulfurization route (DDS) was negatively affected by boron addition. The presence of NP during the HDS of DBT was found to have a significant effect in neither total HDS activity nor the HYD/DDS selec...
RESUMEN La catálisis heterogénea ha sido reconocida como una de las alternativas más promisorias ... more RESUMEN La catálisis heterogénea ha sido reconocida como una de las alternativas más promisorias para la solución integral a muchos de los problemas operacionales y ambientales que presenta la producción de biodiesel convencional. El propósito de esta investigación fue estudiar la actividad catalítica de diferentes catalizadores sólidos de naturaleza básica a partir de MgO, modificándolo mediante tratamientos hidrotérmicos e impregnación húmeda o seca de metales alcalinos, en la transesterificación de triacetina (molécula modelo) con etanol. Se analizó la influencia del: tratamiento hidrotérmico, tipo y cantidad de metal alcalino impregnado (Li, Cs, Rb) y la activación, sobre la basicidad y el comportamiento catalítico de los catalizadores. Las reacciones se realizaron en un sistema batch, con una relación molar etanol:triacetina de 10:1 y 3% en peso de catalizador. La reacción fue seguida por cromatografía de gases. La activación del MgO modificado con Li, Rb o Cs provocó un aument...
In this research, the behavior of calcium methoxide as catalyst for the production of biodiesel f... more In this research, the behavior of calcium methoxide as catalyst for the production of biodiesel from palm oil in a continuous system was studied. Initially, operating conditions such as CaO activation temperature (25°C), reaction temperature (60°C) and molar ratio methanol-oil (10)were established for a batch reactor. Then, the schematic diagram of the experimental setup and its implementation were described for a packed-bed laboratory scale reactor with continuous flow; for this system, yields of methyl esters of 20% with a residence time of 60 min were obtained. The use of co-solvent such as tert-Bbutanol and ethyl acetate in the continuous reaction system was also investigated, aiming to eliminate mass transfer artifacts between the phases and eventually increasing yields to methyl esters. The use of ethyl acetate as co-solvent increased methyl esters yields up to 31 %.
Revista U.D.C.A Actualidad & Divulgación Científica, 2011
INGENIERÍA Y COMPETITIVIDAD, 1970
En el presente trabajo se analizó el comportamiento del metóxido de calcio como catalizador para ... more En el presente trabajo se analizó el comportamiento del metóxido de calcio como catalizador para la producción de biodiesel a partir de aceite de palma. Inicialmente se establecieron condiciones de operación en un reactor por lotes, como temperatura de activación CaO (25°C), temperatura de reacción (60°C) y relación molar metanol/aceite (10). Se describió el montaje y puesta en marcha de un reactor de lecho fijo y flujo continuo a escala laboratorio; a las condiciones establecidas se obtuvieron rendimientos a métilesteres del 20% con un tiempo de residencia de 60 min. También se analizó el uso de cosolventes como el terbutanol y el acetato de etilo para eliminar las limitaciones de transferencia de masa entre las fases e incrementar los rendimientos a metil ésteres. Se encontró que el uso de etil acetato como cosolvente incrementó el rendimiento a metil esteres hasta el 31 %.
Gabriel (2017): Kinetic assessment of the simultaneous hydrodesulfurization of dibenzothiophene a... more Gabriel (2017): Kinetic assessment of the simultaneous hydrodesulfurization of dibenzothiophene and the hydrogenation of diverse polyaromatic structures. ChemRxiv. Preprint. The work presents a kinetic study of the simultaneous hydrodesulfurization of dibenzothiophene and hydrogenation of aromatics with different chemical structures. This kind of studies are seldom reported, since many authors deal almost exclusively with hydrodesulfurization. Furthermore, most of these authors employ power rate laws for kinetic modelling neglecting a rigorous analysis of the thermodynamic parameters of the reactions; namely, adsorption enthalpies and entropies. Considering this fact, we decided to base our kinetic modelling on a Langmuir-Hinshelwood-Hougen-Watson (LHHW) formalism testing the hypothesis of the existence of one or two different catalytic sites for hydrogenation and desulfurization. The consistency of the aforementioned thermodynamic parameters was assessed considering the criteria postulated by Boudart.Our results allowed concluding that a LHHW model considering two actives sites provides a statically satisfactory fitting of experimental data. In addition, it was possible to determine that inhibition effects of aromatics on hydrodesulfurization exist but depend to some extent on the molecular structure of the aromatic.On the other hand, this work also contributes by providing experimental values of adsorption constants of compounds reacting under hydrotreatment conditions which despite the significant advances in theoretical calculations are not yet available in open literature. File list (2) download file view on ChemRxiv Kinetic assessment of the simultaneous hydrodesulfurizati... (2.12 MiB) download file view on ChemRxiv Supporting information.pdf (740.53 KiB) Kinetic assessment of the simultaneous hydrodesulfurization of dibenzothiophene and the hydrogenation of diverse polyaromatic structures
Revista Ion, Investigación, Optimización y Nuevos procesos en Ingeniería, 2017
TiO 2-SiO 2 coatings on fabric samples were obtained by immersion of 9cm 2 of commercial polyeste... more TiO 2-SiO 2 coatings on fabric samples were obtained by immersion of 9cm 2 of commercial polyester in a TiO 2-SiO 2 suspension. This suspension was prepared by adding TiO 2 P25 to a silica matrix obtained from the hydrolysis of tetraethyl orthosilicate (TEOS). The aim of this work was to study the relationship between the immersion time of the fabric on the photocatalytic activity and stability of the coating against several cycles of use and washing. Obtained samples were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and infrared spectroscopy (FTIR-ATR). Evaluation of modified fabrics was performed by self-disinfection tests under 250W/m 2 of simulated sunlight using E. coli as model bacteria. In general, all modified fabrics (except that obtained at 2h immersion time) inactivated bacteria in less than 120min and its regrowth was prevented for at least 24h after the disinfection tests. It was determined that low immersion time (3-4h) lead to active and stable fabrics to 3 cycles of use and washing, whereas higher immersion times (12h) lead to more active but unstable fabrics.
Ingeniería y Ciencia, 2013
En este artículo se presenta el efecto de las sales inorgánicas MgSO4, NaCl y CaCO3 en la desinfe... more En este artículo se presenta el efecto de las sales inorgánicas MgSO4, NaCl y CaCO3 en la desinfección fotocatalítica del agua. Se usó TiO2-P25 como fotocatalizador y E. Coli como microorganismo contaminante. Las pruebas de desinfección se realizaron mediante la iluminación controlada de reactores batch cargados con agua contaminada, sales y TiO2. Los resultados de estas pruebas fueron usados para determinar los parámetros cinéticos de un modelo tipo Langmuir-Hinshelwood. Se encontró que las sales tienen una fuerte influencia sobre la inactivación fotocatalítica de E. Coli, y que cada sal y su concentración afectan la desinfección de forma diferente y en el siguiente orden: NaCl>CaCO3>>MgSO4. Adicionalmente, el valor de los parámetros calculados fue diferente para cada sal, evidenciando que las sales afectan el proceso por varios mecanismos relacionados con las interacciones ion-bacteria, ion-especie oxidante e ion-TiO2.
Revista Colombiana De Quimica, Apr 15, 2009
En este y en el próximo número de la Revista Colombiana de Química se publican, después de haber ... more En este y en el próximo número de la Revista Colombiana de Química se publican, después de haber sido sometidos a evaluación por pares, algunos de los trabajos presentados en dicho Simposio.
Ingenieria Y Universidad, Oct 27, 2010
Modificación de la relación zeolita-matriz en los catalizadores de FCC y su impacto en los rendim... more Modificación de la relación zeolita-matriz en los catalizadores de FCC y su impacto en los rendimientos y la calidad de los destilados medios * Modification of the Zeolite-Matrix Ratio in FCC Catalysts and its Impact on Yields and Quality of Middle Distillates ** Modificação da relação zeólita-matriz nos catalizadores de FCC e seu impacto nos rendimentos e qualidade dos destilados médios ***
Revista Colombiana De Quimica, 2008
Proyecto académico sin fines de lucro, desarrollado bajo la iniciativa de acceso abierto
Revista Ion, 2011
Aplicación de la descomposición del 2-propanol como técnica de caracterización ácido-base de cata... more Aplicación de la descomposición del 2-propanol como técnica de caracterización ácido-base de catalizadores CoMo para hidrotratamiento
We performed quantum mechanics calculations to elucidate the electronic behavior of Pd-Pt bimetal... more We performed quantum mechanics calculations to elucidate the electronic behavior of Pd-Pt bimetallic nanoparticles, using density functional theory, in response to particle size and stoichiometric composition. Using neutrally charged nanoparticles and the Bader charge analysis, we found that external Pd atoms were positively charged, which agrees with previous XPS observations of supported Pd-Pt nanoparticles. From the calculations, unsupported nanoparticles exhibit an electron transfer from Pd to Pt. This result supports the idea that Pd electron-deficient species are possibly responsible of the hydrogenating function of these catalysts, in the hydrodesulfurization of dibenzothiophene. Additionally, it was found that the particle size does not affect the electronic charge distribution and the stoichiometric composition is the factor that greatly influences this property in nanoparticles.
This article presents the effect of inorganic salts MgSO4, NaCl and CaCO3on the photocatalytic wa... more This article presents the effect of inorganic salts MgSO4, NaCl and CaCO3on the photocatalytic water disinfection. TiO2-P25 was used as a photocatalyst, and E. Coli was used as a contaminant. Disinfection tests were performed by controlling lighting of batch reactors loaded with contaminated water, salts and TiO2. The results of these tests were used to determine the kinetic parameters of a type Langmuir-Hinshelwood model. It was found that the salts have a strong influence on the photocatalytic inactivation of E. Coli and that each salt and its concentration affect disinfection differently in the following order: NaCl>CaCO3 >>MgSO4. Additionally, the value of the calculated parameters was different for each salt, showing that the salts affect the process by several mechanisms related to the ion-bacteria interactions, ion-oxidizing species and ion-TiO2.
The development of the hydrodesulfurization (HDS) of dibenzothiophene (DBT) type molecules by the... more The development of the hydrodesulfurization (HDS) of dibenzothiophene (DBT) type molecules by the hydrogenation (HYD) route over Pd-Pt/γ-Al2O3 catalysts was studied through the analysis of the reactivity of naphthalene over these materials. A series of Pd-Pt/γ-Al2O3 catalysts with different Pd/(Pd+Pt) molar ratios were prepared by the coimpregnation method, characterized by atomic absorption and nitrogen adsorption-desorption techniques and tested at temperatures between 503 and 543K and 5MPa. Results show a synergy in the selectivity to trans-decaline. It was concluded that the reaction mechanism of naphthalene over Pd-Pt/γ-Al2O3 bimetallic catalysts entails the roll-over of the Δ1,9-octalina over the catalytic surface. In this way, there exists a similarity with the reaction mechanism of DBT by the HYD route of HDS.
Fuel Processing Technology, 2015
DOI to the publisher's website. • The final author version and the galley proof are versions of t... more DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:
International Journal of Photoenergy, 2012
This paper reports the characterization and photoactivity of Ag-TiO2materials using different amo... more This paper reports the characterization and photoactivity of Ag-TiO2materials using different amounts of silver during the hydrothermal synthesis. Photocatalysts were characterized by means of TEM, XPS, XRD, DRS, and N2sorption isotherms to determine the textural properties. The photocatalyst's configuration was observed to be as anatase-brookite mixed phase particles with Ag partially oxidized aggregates on the TiO2surface, which increased visible light absorption of the material. Moreover, photoproduction of singlet oxygen was followed by EPR analysis under visible light irradiations following the formation of TEMPOL. Such photoproduction was totally decreased by using the singlet oxygen scavenger DABCO. Photocatalysts were tested towards the photocatalytic disinfection of water suing a solar light simulator and an interior-light irradiation setup. Results evidenced an increase in the photooxidative effect of TiO2, while dark processes evidenced that part of the inactivation p...
ABSTRACT Borated aluminas with different boria contents (2, 3, 5 and 8 wt.% B2O3) were prepared t... more ABSTRACT Borated aluminas with different boria contents (2, 3, 5 and 8 wt.% B2O3) were prepared to be used as supports for hydrotreating CoMo catalysts. The borated aluminas were characterized by proton affinity distributions (PAD) to obtain information about changes caused by boron introduction in the surface hydroxyl groups. The later being the sites by means of Mo and Co are anchored to the support. Two new peaks, which cannot be attributed to alumina hydroxyl groups, were found in the PAD profiles of borated aluminas. These two new peaks increased with increasing boria loading, even, in the PAD profile of the alumina with 8 wt.% B2O3 almost no other peaks were present. By comparing PAD profiles with FT-IR spectra of both the OH stretching (3900-3400 cm-1) and the skeletal (under 2000 cm-1) regions, it was possible to assign these new peaks to hydroxyls linked to trigonal and tetrahedral borated species, respectively. Thus, it could be inferred that boria OH groups progressively replaced alumina ones with increasing boria content forming a cover layer. Trigonal borated species were always predominant, however the relative population of tetrahedral species increased with increasing boria content.
Revista UDCA …, 2011
The present work aims to identify the influence of the chemical composition of water on bacterial... more The present work aims to identify the influence of the chemical composition of water on bacterial inactivation using a photocatalyst. Several simulated water matrixes were prepared using different concentrations of (HCO3)-, Cl-,(SO4) 2-,(HPO4) 2-on individual ...
Journal of Photochemistry and Photobiology A: Chemistry, 2010
This study addresses unreported features for Cu DC-magnetron sputtering on cotton mediating inact... more This study addresses unreported features for Cu DC-magnetron sputtering on cotton mediating inactivation of Escherichia coli K12 (from now on E. coli). In-depth profile for the different Cu-species inside the cotton fibers was determined by 5 keV Ar + etching. Sputtering for 40-s deposited 4 × 10 16 atoms Cu/cm 2 (taking ∼10 15 atoms/cm Cu per atomic layer) and this was the threshold amount of Cu necessary for complete bacterial inactivation. This is equivalent to a Cu-loading of 0.060% w/w or 3 nm/15 atomic layers. The inactivation of E. coli was attained within 30 min under visible light (1.2 mW/cm 2) and within 120 min in the dark. XPS identified the Cu-species on the cotton as a function of the sputtering time. For a longer sputtering time of 180 s, the Cu-content was 0.294% w/w, but the bacterial inactivation kinetics under light was observed within 30 min, as was the case for the 40 s sputtered sample. This suggests that Cu-ionic species play a key role E. coli inactivation. The 40 s sputtered samples present the highest amount of Cu-sites held in exposed positions interacting on the cotton surface (or inside the cotton) with E. coli. Confocal microscopy shows the higher rugosity of Cu-cotton fibers compared to bare cotton fibers. The Cu-clusters were observed to be ∼50 nm after 40 s DC-magnetron sputtering and presented a wide size distribution. Cu DC-magnetron sputtering leads to thin metallic semi-transparent grey-brown Cu-coating presenting a moderate hydrophobic behavior as determined by contact angle measurements.