Laura Palacio - Academia.edu (original) (raw)

Papers by Laura Palacio

Membranes

Mixed-matrix membranes (MMMs) consisting of an ortho-hydroxy polyamide (HPA) matrix, and variable... more Mixed-matrix membranes (MMMs) consisting of an ortho-hydroxy polyamide (HPA) matrix, and variable loads of a porous polymer network (PPN) were thermally treated to induce the transformation of HPA to polybenzoxazole (β-TR-PBO). Two different HPAs were synthesized to be used as a matrix, 6FCl-APAF and tBTpCl-APAF, while the PPN used as a filler was prepared by reacting triptycene and trifluoroacetophenone. The permeability of He, H2, N2, O2, CH4 and CO2 gases through these MMMs are analyzed as a function of the fraction of free volume (FFV) of the membrane and the kinetic diameter of the gas, allowing for the evaluation of the free volume. Thermal rearrangement entails an increase in the FFV. Both before and after thermal rearrangement, the free volume increases with the PPN content very similarly for both polymeric matrices. It is shown that there is a portion of free volume that is inaccessible to permeation (occluded volume), probably due to it being trapped within the filler. In ...

superficial: imágenes topográficas (AFM) A4. Porosidades A5. Distribución de tamaños de poro A6. ... more superficial: imágenes topográficas (AFM) A4. Porosidades A5. Distribución de tamaños de poro A6. Caracterización eléctrica A7. Estudio de la hidrofobicidad e hidrofilicidad B. Membranas de polisulfona B1. Descripción de las membranas B2. Análisis de la composición de la membrana B3. Caracterización de la estructura superficial: AFM y SEM B4. Porosidades B5. Distribución de tamaños de poro B6. Caracterización eléctrica B7. Estudio de la hidrofobicidad e hidrofilicidad C. Membranas cerámicas tubulares C1. Descripción de las membranas C2. Caracterización de la estructura superficial: imágenes topográficas (AFM) C3. Porosidades C4. Distribución de tamaños de poro Referencias Capítulo 6: CONCLUSIONES

Membranes, 2022

Forward osmosis (FO) is a promising technology for the treatment of urban wastewater. FO can prod... more Forward osmosis (FO) is a promising technology for the treatment of urban wastewater. FO can produce high-quality effluents and preconcentrate urban wastewater for subsequent anaerobic treatment. This membrane technology makes it possible to eliminate the pollutants present in urban wastewater, which can cause adverse effects in the ecosystem even at low concentrations. In this study, a 0.6 m2 hollow fiber aquaporin forward osmosis membrane was used for the treatment of urban wastewater from the Valladolid wastewater treatment plant (WWTP). A total of 51 Contaminants of Emerging Concern (CECs) were investigated, of which 18 were found in the target urban wastewater. They were quantified, and their ecotoxicological risk impact was evaluated. Different salts with different concentrations were tested as draw solutions to evaluate the membrane performances when working with pretreated urban wastewater. NaCl was found to be the most appropriate salt since it leads to higher permeate flux...

European Polymer Journal, 2018

Herein, a new approach to achieve gas separation materials with improved resistance to plasticiza... more Herein, a new approach to achieve gas separation materials with improved resistance to plasticization (obtained by partial pyrolysis of new polyimide blends) is presented. Blends of an aromatic polyimide (formally, 6FDA-6FpDA) and aliphatic-aromatic copolyetherimides based on the same polyimide in combination with other aliphatic polyimides, having polyethylene oxide moieties, were obtained. After their synthesis and characterization, a selective elimination of the polyether by thermal treatment was carried and the obtained partiallypyrolyzed materials were tested as gas separation membranes. For neat blends, permeability was shown to decrease when PEO content increases. This effect is due to polyethylene oxide (PEO) chains encroaching on free volume because phase segregation was minimized. When these blends were subjected to thermal treatment at relatively low temperatures in air or in N 2 , it was clearly observed that all the polyether moieties were selectively eliminated from the structure, which gave rise to an increase of permeability. Higher permeabilities were obtained after a thermal treatment at 390°C in N 2. Degradation of PEO chains after a 290°C treatment in air produced materials with permeability values lower than those observed under N 2. In both cases, even though PEO was selectively and wholly eliminated, permeability was not totally recovered to give the values observed for neat 6FDA-6FpDA due probably to a combination of shrinkage and crosslinking of the membrane produced during the thermal process. Crosslinking provides the materials with an increased resistance to plasticization. In particular, the best improvement against plasticization proceeded from the thermal treatments of blends at 290°C in air.

Membranes, 2021

Ammonia recovery from synthetic and real anaerobic digestates was accomplished using hydrophobic ... more Ammonia recovery from synthetic and real anaerobic digestates was accomplished using hydrophobic flat sheet membranes operated with H2SO4 solutions to convert ammonia into ammonium sulphate. The influence of the membrane material, flow rate (0.007, 0.015, 0.030 and 0.045 m3 h−1) and pH (7.6, 8.9, 10 and 11) of the digestate on ammonia recovery was investigated. The process was carried out with a flat sheet configuration at a temperature of 35 °C and with a 1 M, or 0.005 M, H2SO4 solution on the other side of the membrane. Polytetrafluoroethylene membranes with a nominal pore radius of 0.22 µm provided ammonia recoveries from synthetic and real digestates of 84.6% ± 1.0% and 71.6% ± 0.3%, respectively, for a membrane area of 8.6 × 10−4 m2 and a reservoir volume of 0.5 L, in 3.5 h with a 1 M H2SO4 solution and a recirculation flow on the feed side of the membrane of 0.030 m3 h−1. NH3 recovery followed first order kinetics and was faster at higher pHs of the H2SO4 solution and recircul...

Surface Chemistry and Electrochemistry of Membranes

La Ciencia y Tecnologia de Membranas es una ciencia en auge y con cada vez mayor presencia en mas... more La Ciencia y Tecnologia de Membranas es una ciencia en auge y con cada vez mayor presencia en mas ambitos, no solo industriales sino de la vida cotidiana. Algunos ejemplos muy cercanos son: la filtracion de aire en el interior de edificios o vehiculos, la industria de la alimentacion (leche, zumos, vino, cerveza, alimentos enriquecidos o funcionales), purificacion de agua potable, tratamiento de aguas residuales o de desecho industrial. Mas en el ambito cientifico encontramos membranas en muchas separaciones analiticas en laboratorios de quimica o farmacia. Tambien son muy relevantes las aplicaciones medicas como en la hemodialisis con rinones y otros organos artificiales.

Polymers

A hydroxypolyamide (HPA) manufactured from 2,2-bis(3-amino-4-hydroxy phenyl)-hexafluoropropane (A... more A hydroxypolyamide (HPA) manufactured from 2,2-bis(3-amino-4-hydroxy phenyl)-hexafluoropropane (APAF) diamine and 5′-terbutyl-m-terphenyl-4,4′′-dicarboxylic acid chloride (tBTpCl), and a copolyimide produced by stochiometric copolymerization of APAF and 4,4′-(hexafluoroisopropylidene) diamine (6FpDA), using the same diacid chloride, were obtained and used as polymeric matrixes in mixed matrix membranes (MMMs) loaded with 20% (w/w) of two porous polymer networks (triptycene-isatin, PPN-1, and triptycene-trifluoroacetophenone, PPN-2). These MMMs, and also the thermally rearranged membranes (TR-MMMs) that underwent a thermal treatment process to convert the o-hydroxypolyamide moieties to polybenzoxazole ones, were characterized, and their gas separation properties evaluated for H2, N2, O2, CH4, and CO2. Both TR process and the addition of PPN increased permeability with minor decreases in selectivity for all gases tested. Excellent results were obtained, in terms of the permeability ve...

Polymers

A commercial ultrafiltration (UF) membrane (HFM-183 de Koch Membrane Systems) made of poly(vinyli... more A commercial ultrafiltration (UF) membrane (HFM-183 de Koch Membrane Systems) made of poly(vinylidene fluoride) (PVDF), was recovered with a negatively-charged polyelectrolyte (poly(sodium 4-styrenesulfonate)) (PSS), and the effects on its electric, chemical, and morphological properties were analyzed. Atomic force microscopy (AFM), liquid–liquid displacement porometry, Electrical Impedance Spectroscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy were used to investigate the modifications induced by the deposition of PSS on the PVDF positively-charged membrane and after its treatment by a radio frequency Ar-plasma. These techniques confirmed a real deposition and posterior compaction of PSS with increasing roughness and decreasing pore sizes. The evolution of the electric resistances of the membranes confirmed crosslinking and compaction with shielding of the sulfonated groups from PSS. In this way, a membrane with a negatively-charged active layer and a pore size whic...

Boletín de la Sociedad Española de Cerámica y Vidrio

En este trabajo se ha estudiado la influencia del tamaño de partículas y de la temperatura de sin... more En este trabajo se ha estudiado la influencia del tamaño de partículas y de la temperatura de sinterizado en la preparación de membranas planas de microfiltración. Estas membranas se prepararon a partir de materias primas cerámicas controlando, entre otras variables: el tamaño de partículas, la formulación química de la pasta y su tratamiento térmico. La morfología estructural de las membranas en función del tamaño de partícula y la temperatura de sinterizado ha sido estudiada mediante técnicas de porosimetría de mercurio y porometría de aire-líquido. Las dos técnicas de análisis han sido utilizadas por su complementariedad, puesto que la porosimetría de mercurio informa sobre los poros totales, mientras que la porometría de aire-líquido lo hace sobre los poros activos. Los resultados muestran que tanto el tamaño de los poros activos como de los totales, se incrementa con el tamaño de partícula de la pasta empleada. De forma similar, el incremento de la temperatura de sinterizado (dentro del rango de trabajo) produce un aumento del tamaño medio de poro y un ensanchamiento de la distribución. Palabras clave: Materiales porosos, Membranas cerámicas, Síntesis de membranas planas, Microfiltración, Temperatura de sinterizado. Study of the pore size distribution of active and total pores in microfiltration ceramic flat membranes In this work, it has been studied the influence of the particles size and sinterization temperature in the preparation of flat microfiltration ceramic membranes. These membranes were made from ceramic materials by controlling, among other factors, the particle size, the chemical formulation of the paste and its thermal treatment. The structural morphology of the membranes has been studied as a function of particle size and sinterization temperature, by using mercury porosimetry and air-liquid porometry. Both techniques have been used due to their complementarity, as far as mercury porosimetry gives information on total pores, while air-liquid porometry does it on active pores. Results showed that both active and total pores size, are incremented with the size of the used particles. Similarly, the increase of the sinterization temperature (within the range of work) results in an increase of the mean pore size and a broadening of the distribution.

Boletín de la Sociedad Española de Cerámica y Vidrio

En este trabajo se describe el método de preparación y la caracterización de diversas membranas c... more En este trabajo se describe el método de preparación y la caracterización de diversas membranas cerámicas tubulares con utilidad en el campo de la microfiltración. Se trata de membranas compuestas formadas por un soporte macroporoso que le confiere resistencia mecánica y una capa delgada microporosa o superficie activa depositada sobre el soporte que es la que determina las características retentivas de la membrana. Se prepararon diversas versiones de estas membranas a partir de materias primas cerámicas controlando, entre otras, variables como: el tamaño de partículas, la formulación química de la pasta y su tratamiento térmico. El material del soporte y de la capa activa se obtiene a partir de barbotinas a base de caolín, arcilla, feldespato, alúmina, etc. La morfología estructural del soporte, capa activa y membrana compuesta se ha estudiado mediante técnicas de AFM (Microscopía de Fuerza Atómica) y permeabilidades hidráulicas. Las propiedades estructurales y permeoselectivas de estas membranas cerámicas, hacen que sean apropiadas para procesos de microfiltración. Palabras Clave: Materiales porosos, membranas, síntesis de membranas tubulares, microfiltración, microcopía de fuerza atómica. fabrication and characterization of microfiltration tubular ceramic membranes A method to prepare and characterize different microfiltration ceramic membranes is described here. The membranes are composite and consist in a macroporous support, giving high mechanical resistance, onto which a thin microporous layer is deposited. This active film determines the retention properties of the membrane. Several versions of these membranes were prepared by controlling: particle size, chemical formulation of the paste and its thermal treatment. Both the support and the active layer were obtained from slips consisting in caolin, clay, feldespatum etc. The morphology of the active layer, support and composite membrane have been investigated by AFM (Atomic Force Microscopy) and hydraulic permeabilities. Structural properties and permselectivity make these membranes appropriate to be efficiently used in microfiltration processes..

Desalination and Water Treatment, 2015

The phase inversion method was used to prepare polyacrylonitrile membranes modified with single-w... more The phase inversion method was used to prepare polyacrylonitrile membranes modified with single-walled carbon nanotubes. The influence of the amount and the kind of carbon nanotubes (CNTs) (pristine and functionalized with carboxyl groups) were determined analysing the structure of membranes, hydrophobic-hydrophilic characteristics, zeta potential, and transport-separation properties. Based on the microscopic analysis, it was established that their structure changed depending on the amount of nanotubes added. The membranes with the highest content of CNTs were characterized by the highest membrane capacity. Those membranes were used in low pressure filtration in order to remove micropollutants from synthetic wastewater. The effectiveness of micropollutants removal was dependant on the kind of membrane-in the range 15-65% for bisphenol A, and 25-87% for nonylphenol. The key mechanism in separation of low molecular organic compounds was the sorption phenomenon intensified by the presence of CNTs.

Boletín de la Sociedad Española de Cerámica y Vidrio, 2004

En este trabajo se ha comparado los resultados de caracterización de membranas de microfiltración... more En este trabajo se ha comparado los resultados de caracterización de membranas de microfiltración por diversas técnicas microscópicas:

ACS National Meeting Book of Abstracts

Monitoring and Visualizing Membrane-Based Processes, 2009

European Polymer Journal, 2015

In our previous works, it was observed a clear relationship between the structure and the propert... more In our previous works, it was observed a clear relationship between the structure and the properties for different copoly(ether-imide)s, besides a good relation was found between SAXS characterization and permeability results. Here, a series of aliphatic aromatic copoly(ether-imide)s, based on an aromatic diamine (ODA), a diamine terminated poly(ethylene oxide) (PEO2000) of a molecular weight of 2000 g/mol and different aromatic dianhydrides (BPDA, BKDA (or BTDA) and PMDA)has been synthesized and characterized. The permeability for O2, N2, CO2 and CH4, increased with the rigidity of the monomers (BKDA < BPDA < PMDA), with the amount of PEO2000 in the copolymers, as well as with the increase in the temperature of treatment of the films. In this case, it was observed that when the proportion of PEO in the copolymer exceeded 50%, the permeability was similar for all samples, and the aromatic portion had no significant influence. Attending to glass transition temperature, Tg, of the aliphatic part, to its melting temperature, Tm, and to its crystallinity, segregation was better for more rigid dianhydrides at lower temperatures of treatment. Higher dianhydride rigidity produced better mechanical properties that were good but decreased a little bit when the percentage of PEO in the samples increased. Good permeselectivity compromises were attained for the CO2/N2 separation .This work gives light to design advanced materials for this separation with the increasing possibilities of controled structure and properties.

Procedia Engineering, 2012

Membranes

Mixed-matrix membranes (MMMs) consisting of an ortho-hydroxy polyamide (HPA) matrix, and variable... more Mixed-matrix membranes (MMMs) consisting of an ortho-hydroxy polyamide (HPA) matrix, and variable loads of a porous polymer network (PPN) were thermally treated to induce the transformation of HPA to polybenzoxazole (β-TR-PBO). Two different HPAs were synthesized to be used as a matrix, 6FCl-APAF and tBTpCl-APAF, while the PPN used as a filler was prepared by reacting triptycene and trifluoroacetophenone. The permeability of He, H2, N2, O2, CH4 and CO2 gases through these MMMs are analyzed as a function of the fraction of free volume (FFV) of the membrane and the kinetic diameter of the gas, allowing for the evaluation of the free volume. Thermal rearrangement entails an increase in the FFV. Both before and after thermal rearrangement, the free volume increases with the PPN content very similarly for both polymeric matrices. It is shown that there is a portion of free volume that is inaccessible to permeation (occluded volume), probably due to it being trapped within the filler. In ...

superficial: imágenes topográficas (AFM) A4. Porosidades A5. Distribución de tamaños de poro A6. ... more superficial: imágenes topográficas (AFM) A4. Porosidades A5. Distribución de tamaños de poro A6. Caracterización eléctrica A7. Estudio de la hidrofobicidad e hidrofilicidad B. Membranas de polisulfona B1. Descripción de las membranas B2. Análisis de la composición de la membrana B3. Caracterización de la estructura superficial: AFM y SEM B4. Porosidades B5. Distribución de tamaños de poro B6. Caracterización eléctrica B7. Estudio de la hidrofobicidad e hidrofilicidad C. Membranas cerámicas tubulares C1. Descripción de las membranas C2. Caracterización de la estructura superficial: imágenes topográficas (AFM) C3. Porosidades C4. Distribución de tamaños de poro Referencias Capítulo 6: CONCLUSIONES

Membranes, 2022

Forward osmosis (FO) is a promising technology for the treatment of urban wastewater. FO can prod... more Forward osmosis (FO) is a promising technology for the treatment of urban wastewater. FO can produce high-quality effluents and preconcentrate urban wastewater for subsequent anaerobic treatment. This membrane technology makes it possible to eliminate the pollutants present in urban wastewater, which can cause adverse effects in the ecosystem even at low concentrations. In this study, a 0.6 m2 hollow fiber aquaporin forward osmosis membrane was used for the treatment of urban wastewater from the Valladolid wastewater treatment plant (WWTP). A total of 51 Contaminants of Emerging Concern (CECs) were investigated, of which 18 were found in the target urban wastewater. They were quantified, and their ecotoxicological risk impact was evaluated. Different salts with different concentrations were tested as draw solutions to evaluate the membrane performances when working with pretreated urban wastewater. NaCl was found to be the most appropriate salt since it leads to higher permeate flux...

European Polymer Journal, 2018

Herein, a new approach to achieve gas separation materials with improved resistance to plasticiza... more Herein, a new approach to achieve gas separation materials with improved resistance to plasticization (obtained by partial pyrolysis of new polyimide blends) is presented. Blends of an aromatic polyimide (formally, 6FDA-6FpDA) and aliphatic-aromatic copolyetherimides based on the same polyimide in combination with other aliphatic polyimides, having polyethylene oxide moieties, were obtained. After their synthesis and characterization, a selective elimination of the polyether by thermal treatment was carried and the obtained partiallypyrolyzed materials were tested as gas separation membranes. For neat blends, permeability was shown to decrease when PEO content increases. This effect is due to polyethylene oxide (PEO) chains encroaching on free volume because phase segregation was minimized. When these blends were subjected to thermal treatment at relatively low temperatures in air or in N 2 , it was clearly observed that all the polyether moieties were selectively eliminated from the structure, which gave rise to an increase of permeability. Higher permeabilities were obtained after a thermal treatment at 390°C in N 2. Degradation of PEO chains after a 290°C treatment in air produced materials with permeability values lower than those observed under N 2. In both cases, even though PEO was selectively and wholly eliminated, permeability was not totally recovered to give the values observed for neat 6FDA-6FpDA due probably to a combination of shrinkage and crosslinking of the membrane produced during the thermal process. Crosslinking provides the materials with an increased resistance to plasticization. In particular, the best improvement against plasticization proceeded from the thermal treatments of blends at 290°C in air.

Membranes, 2021

Ammonia recovery from synthetic and real anaerobic digestates was accomplished using hydrophobic ... more Ammonia recovery from synthetic and real anaerobic digestates was accomplished using hydrophobic flat sheet membranes operated with H2SO4 solutions to convert ammonia into ammonium sulphate. The influence of the membrane material, flow rate (0.007, 0.015, 0.030 and 0.045 m3 h−1) and pH (7.6, 8.9, 10 and 11) of the digestate on ammonia recovery was investigated. The process was carried out with a flat sheet configuration at a temperature of 35 °C and with a 1 M, or 0.005 M, H2SO4 solution on the other side of the membrane. Polytetrafluoroethylene membranes with a nominal pore radius of 0.22 µm provided ammonia recoveries from synthetic and real digestates of 84.6% ± 1.0% and 71.6% ± 0.3%, respectively, for a membrane area of 8.6 × 10−4 m2 and a reservoir volume of 0.5 L, in 3.5 h with a 1 M H2SO4 solution and a recirculation flow on the feed side of the membrane of 0.030 m3 h−1. NH3 recovery followed first order kinetics and was faster at higher pHs of the H2SO4 solution and recircul...

Surface Chemistry and Electrochemistry of Membranes

La Ciencia y Tecnologia de Membranas es una ciencia en auge y con cada vez mayor presencia en mas... more La Ciencia y Tecnologia de Membranas es una ciencia en auge y con cada vez mayor presencia en mas ambitos, no solo industriales sino de la vida cotidiana. Algunos ejemplos muy cercanos son: la filtracion de aire en el interior de edificios o vehiculos, la industria de la alimentacion (leche, zumos, vino, cerveza, alimentos enriquecidos o funcionales), purificacion de agua potable, tratamiento de aguas residuales o de desecho industrial. Mas en el ambito cientifico encontramos membranas en muchas separaciones analiticas en laboratorios de quimica o farmacia. Tambien son muy relevantes las aplicaciones medicas como en la hemodialisis con rinones y otros organos artificiales.

Polymers

A hydroxypolyamide (HPA) manufactured from 2,2-bis(3-amino-4-hydroxy phenyl)-hexafluoropropane (A... more A hydroxypolyamide (HPA) manufactured from 2,2-bis(3-amino-4-hydroxy phenyl)-hexafluoropropane (APAF) diamine and 5′-terbutyl-m-terphenyl-4,4′′-dicarboxylic acid chloride (tBTpCl), and a copolyimide produced by stochiometric copolymerization of APAF and 4,4′-(hexafluoroisopropylidene) diamine (6FpDA), using the same diacid chloride, were obtained and used as polymeric matrixes in mixed matrix membranes (MMMs) loaded with 20% (w/w) of two porous polymer networks (triptycene-isatin, PPN-1, and triptycene-trifluoroacetophenone, PPN-2). These MMMs, and also the thermally rearranged membranes (TR-MMMs) that underwent a thermal treatment process to convert the o-hydroxypolyamide moieties to polybenzoxazole ones, were characterized, and their gas separation properties evaluated for H2, N2, O2, CH4, and CO2. Both TR process and the addition of PPN increased permeability with minor decreases in selectivity for all gases tested. Excellent results were obtained, in terms of the permeability ve...

Polymers

A commercial ultrafiltration (UF) membrane (HFM-183 de Koch Membrane Systems) made of poly(vinyli... more A commercial ultrafiltration (UF) membrane (HFM-183 de Koch Membrane Systems) made of poly(vinylidene fluoride) (PVDF), was recovered with a negatively-charged polyelectrolyte (poly(sodium 4-styrenesulfonate)) (PSS), and the effects on its electric, chemical, and morphological properties were analyzed. Atomic force microscopy (AFM), liquid–liquid displacement porometry, Electrical Impedance Spectroscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy were used to investigate the modifications induced by the deposition of PSS on the PVDF positively-charged membrane and after its treatment by a radio frequency Ar-plasma. These techniques confirmed a real deposition and posterior compaction of PSS with increasing roughness and decreasing pore sizes. The evolution of the electric resistances of the membranes confirmed crosslinking and compaction with shielding of the sulfonated groups from PSS. In this way, a membrane with a negatively-charged active layer and a pore size whic...

Boletín de la Sociedad Española de Cerámica y Vidrio

En este trabajo se ha estudiado la influencia del tamaño de partículas y de la temperatura de sin... more En este trabajo se ha estudiado la influencia del tamaño de partículas y de la temperatura de sinterizado en la preparación de membranas planas de microfiltración. Estas membranas se prepararon a partir de materias primas cerámicas controlando, entre otras variables: el tamaño de partículas, la formulación química de la pasta y su tratamiento térmico. La morfología estructural de las membranas en función del tamaño de partícula y la temperatura de sinterizado ha sido estudiada mediante técnicas de porosimetría de mercurio y porometría de aire-líquido. Las dos técnicas de análisis han sido utilizadas por su complementariedad, puesto que la porosimetría de mercurio informa sobre los poros totales, mientras que la porometría de aire-líquido lo hace sobre los poros activos. Los resultados muestran que tanto el tamaño de los poros activos como de los totales, se incrementa con el tamaño de partícula de la pasta empleada. De forma similar, el incremento de la temperatura de sinterizado (dentro del rango de trabajo) produce un aumento del tamaño medio de poro y un ensanchamiento de la distribución. Palabras clave: Materiales porosos, Membranas cerámicas, Síntesis de membranas planas, Microfiltración, Temperatura de sinterizado. Study of the pore size distribution of active and total pores in microfiltration ceramic flat membranes In this work, it has been studied the influence of the particles size and sinterization temperature in the preparation of flat microfiltration ceramic membranes. These membranes were made from ceramic materials by controlling, among other factors, the particle size, the chemical formulation of the paste and its thermal treatment. The structural morphology of the membranes has been studied as a function of particle size and sinterization temperature, by using mercury porosimetry and air-liquid porometry. Both techniques have been used due to their complementarity, as far as mercury porosimetry gives information on total pores, while air-liquid porometry does it on active pores. Results showed that both active and total pores size, are incremented with the size of the used particles. Similarly, the increase of the sinterization temperature (within the range of work) results in an increase of the mean pore size and a broadening of the distribution.

Boletín de la Sociedad Española de Cerámica y Vidrio

En este trabajo se describe el método de preparación y la caracterización de diversas membranas c... more En este trabajo se describe el método de preparación y la caracterización de diversas membranas cerámicas tubulares con utilidad en el campo de la microfiltración. Se trata de membranas compuestas formadas por un soporte macroporoso que le confiere resistencia mecánica y una capa delgada microporosa o superficie activa depositada sobre el soporte que es la que determina las características retentivas de la membrana. Se prepararon diversas versiones de estas membranas a partir de materias primas cerámicas controlando, entre otras, variables como: el tamaño de partículas, la formulación química de la pasta y su tratamiento térmico. El material del soporte y de la capa activa se obtiene a partir de barbotinas a base de caolín, arcilla, feldespato, alúmina, etc. La morfología estructural del soporte, capa activa y membrana compuesta se ha estudiado mediante técnicas de AFM (Microscopía de Fuerza Atómica) y permeabilidades hidráulicas. Las propiedades estructurales y permeoselectivas de estas membranas cerámicas, hacen que sean apropiadas para procesos de microfiltración. Palabras Clave: Materiales porosos, membranas, síntesis de membranas tubulares, microfiltración, microcopía de fuerza atómica. fabrication and characterization of microfiltration tubular ceramic membranes A method to prepare and characterize different microfiltration ceramic membranes is described here. The membranes are composite and consist in a macroporous support, giving high mechanical resistance, onto which a thin microporous layer is deposited. This active film determines the retention properties of the membrane. Several versions of these membranes were prepared by controlling: particle size, chemical formulation of the paste and its thermal treatment. Both the support and the active layer were obtained from slips consisting in caolin, clay, feldespatum etc. The morphology of the active layer, support and composite membrane have been investigated by AFM (Atomic Force Microscopy) and hydraulic permeabilities. Structural properties and permselectivity make these membranes appropriate to be efficiently used in microfiltration processes..

Desalination and Water Treatment, 2015

The phase inversion method was used to prepare polyacrylonitrile membranes modified with single-w... more The phase inversion method was used to prepare polyacrylonitrile membranes modified with single-walled carbon nanotubes. The influence of the amount and the kind of carbon nanotubes (CNTs) (pristine and functionalized with carboxyl groups) were determined analysing the structure of membranes, hydrophobic-hydrophilic characteristics, zeta potential, and transport-separation properties. Based on the microscopic analysis, it was established that their structure changed depending on the amount of nanotubes added. The membranes with the highest content of CNTs were characterized by the highest membrane capacity. Those membranes were used in low pressure filtration in order to remove micropollutants from synthetic wastewater. The effectiveness of micropollutants removal was dependant on the kind of membrane-in the range 15-65% for bisphenol A, and 25-87% for nonylphenol. The key mechanism in separation of low molecular organic compounds was the sorption phenomenon intensified by the presence of CNTs.

Boletín de la Sociedad Española de Cerámica y Vidrio, 2004

En este trabajo se ha comparado los resultados de caracterización de membranas de microfiltración... more En este trabajo se ha comparado los resultados de caracterización de membranas de microfiltración por diversas técnicas microscópicas:

ACS National Meeting Book of Abstracts

Monitoring and Visualizing Membrane-Based Processes, 2009

European Polymer Journal, 2015

In our previous works, it was observed a clear relationship between the structure and the propert... more In our previous works, it was observed a clear relationship between the structure and the properties for different copoly(ether-imide)s, besides a good relation was found between SAXS characterization and permeability results. Here, a series of aliphatic aromatic copoly(ether-imide)s, based on an aromatic diamine (ODA), a diamine terminated poly(ethylene oxide) (PEO2000) of a molecular weight of 2000 g/mol and different aromatic dianhydrides (BPDA, BKDA (or BTDA) and PMDA)has been synthesized and characterized. The permeability for O2, N2, CO2 and CH4, increased with the rigidity of the monomers (BKDA < BPDA < PMDA), with the amount of PEO2000 in the copolymers, as well as with the increase in the temperature of treatment of the films. In this case, it was observed that when the proportion of PEO in the copolymer exceeded 50%, the permeability was similar for all samples, and the aromatic portion had no significant influence. Attending to glass transition temperature, Tg, of the aliphatic part, to its melting temperature, Tm, and to its crystallinity, segregation was better for more rigid dianhydrides at lower temperatures of treatment. Higher dianhydride rigidity produced better mechanical properties that were good but decreased a little bit when the percentage of PEO in the samples increased. Good permeselectivity compromises were attained for the CO2/N2 separation .This work gives light to design advanced materials for this separation with the increasing possibilities of controled structure and properties.

Procedia Engineering, 2012