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Surface functionalization of cellulosic substrates by using chemical and biotechnological methodsCusola i Aumedes, Oriol 20 December 2013 (has links)
This thesis deals with the surface modification of cellulosic substrates by use of chemo-enzymatic methods. Functionalizing cellulose is intended to adjust its properties for various purposes, but particularly for obtaining a chemical feedstock for the production of cellulose derivatives with a variety of uses. At present, cellulosic substrates are chemically or enzymatically modified by treating fibres in aqueous suspensions prior to formation substrates. In this doctoral work, treatments were applied to previously formed cellulosic substrates (FCS), providing advantages in terms of sheet formation, chemical consumption and manufacturing speed. A non-enzymatic and an enzymatic approach to substrate functionalization were examined, with emphasis on the latter.
This work is part of the research conducted by the CELBIOTECH Group (UPC-BarcelonaTech) within the framework of Spain's MICINN Projects FUNCICEL (CTQ2009-12904), BIOSURFACEL (CTQ2012-34109) and BIOFIBRECELL (CTQ2010-20238-CO3-01), and the BIORENEW integrated project of the Sixth Framework Program (NMP2-CT-2006-026456).
β--cyclodextrins (β--CD) were used to facilitate the chemical modification of three different commercial FCS. Grafting of the substrates was assessed by scanning electron microscopy and FTIR analysis. Drug delivery kinetics were analyzed by UV spectroscopy after loading of the β--CD-grafted substrates with chlorhexidine digluconate (digCHX). Several grafted substrates were found to absorb substantial amounts of active molecules and to release them over a long period (about 20 days).
The use of enzyme systems for surface treatments of FCS is still in its infancy. This doctoral work was intended to fill the gap as far as possible. In preliminary tests, the surface hydrophobization was accomplished onto commercial FCS by using laccase in combination with hydrophobic compounds. The efficiency of the method was increased by using lignosulfonates, which improved the surface distribution of hydrophobic compounds, increased hydrophobicity and helped preserve enzyme activity. The influence of processing conditions including LG dose and treatment time was examined, with a view to their optimization for further increased hydrophobicity.
Surface enzyme treatments evolved into the preparation of a functionalization solution (FS), consisting of an enzymatic product that was subsequently applied to the surface of FCS. This method was also effective and provided major advantages for industrial implementation; in fact, it is the subject of an international patent application. Surface application of the functionalization solution to FCS was found to confer them hydrophobic and antioxidant properties by effect of physico-chemical interactions between FS and the substrate. Cellulose model surfaces were used to assess FS adsorption, and the WDT, WCA, SEM, AFM and SFE techniques to characterize the treated FCS. Efficient fibre bonding and chemical functionalization were confirmed by thorough washing and Soxhlet extraction of the substrates. As shown here for the first time, surface enzyme treatments have the potential to confer advanced properties to FCS. The performance of the proposed cellulose functionalization technique was assessed by using laccases from various microorganisms.
A better understanding of the reaction mechanisms and physico-chemical interactions behind the laccase treatments, and also of FS-substrate interactions, was acquired by using various analytical techniques including DLS, QCM, FTIR, UV-VIS spectroscopy, Z-potential, Turbiscan® and cyclic voltammetry. The chemical structure of the resulting enzyme-oxidized molecules, the sequence for the oxidation reaction, and the potential grafting mechanisms of enzyme-modified compounds to cellulose, were proposed. The effects of the alkyl chain length of the gallates studied and curing treatments used were analysed in terms of the development of hydrophobic and antioxidant properties. / La present tesi tracta sobre la modificació superficial de substrats cel·lulòsics utilitzant mètodes químics i enzimàtics. La funcionalització de la cel·lulosa consisteix en ajustar-ne les seves propietats, per a poder-la utilitzar en gran varietat d'aplicacions. Habitualment aquesta modificació s'aconsegueix tractant les fibres en suspensió aquosa i abans de la formació del substrat. No obstant, en la present tesi els tractaments s'apliquen utilitzant substrats cel·lulòsics ja formats (FCS), obtenint una sèrie d'avantatges en termes de formació, consum de químics, i velocitat de fabricació. S’han estudiat dos enfocaments diferents per a la funcionalització: tècniques no-enzimàtiques i enzimàtiques. Els esforços s’han centrat en l'enfoc enzimàtic.
Aquest treball es va dur a terme en el grup de recerca CELBIOTECH (UPCBarcelonTech), en el marc dels projectes FUNCICEL (CTQ2009-12904), BIOSURFACEL (CTQ2012-34109) , BIOFIBRECELL (CTQ2010-20238-CO3-01), del MICINN Espanyol i el Projecte integrat BIORENEW (NMP2-CT-2006-026456) del sisè Programa Marc.
Pel que fa a la funcionalització no-enzimàtica, s’han utilitzat β-ciclodextrines (β-CD) per a la modificació superficial de tres FCS comercials. L'empelt s’ha avaluat mitjançant microscòpia electrònica de rastreig i anàlisi FTIR. Els substrats empeltats amb β-CDs s’han carregat amb digluconat de clorhexidina (digCHX), i s’ha analitzat l’alliberament d’aquest principi actiu utilitzant espectroscòpia UV. Diversos substrats han estat capaços de retenir quantitats significatives de digCHX, i de mantenir-ne l’alliberament durant períodes de temps de fins a 20 dies.
La funcionalització enzimàtica per al desenvolupament de derivats de la cel·lulosa ha guanyat interès en la comunitat científica i industrial darrerament. No obstant, l'ús de sistemes enzimàtics superficials encara es troba en una fase molt prematura; la present tesi fa èmfasi en aquest aspecte. En un primer estudi s’analitza la hidrofobització superficial de FCS comercials, mitjançant una lacasa en combinació amb compostos
hidròfobs. L'eficiència s’ha vist augmentada amb l'ús de lignosulfonats (SL), els quals milloren la distribució superficial, augmenten els nivells d’hidrofobicitat, i ajuden a preservar l'activitat enzimàtica. La dosi de LG i el temps de tractament s’han optimitzat resultant en una major hidrofobicitat.
Seguidament, els tractaments han evolucionat cap a un nou mètode basat en l’obtenció d'una solució funcionalitzadora (FS), consistent en un producte derivat d’una reacció enzimàtica, el qual és aplicat posteriorment a la superfície dels FCS. Aquest mètode també s’ha mostrat efectiu, i proporciona avantatges importants respecte a la possible aplicació industrial; de fet, el nou mètode ha permès realitzar una sol·licitud internacional
de patent. L’aplicació de la FS a la superfície de FCS els confereix propietats hidrofòbica i antioxidant gràcies a les interaccions fisicoquímiques que es produeixen. S’han utilitzat superfícies model de cel·lulosa per tal d’avaluar l'adsorció de la FS, i s’han emprat les tècniques de WDT, WCA, SEM, AFM i SFE per caracteritzar-les. La força de l’enllaç s’avalua mitjançant rentats agressius i extraccions Soxhlet. Es demostra per primer cop el potencial dels tractaments enzimàtics superficials per a conferir propietats avançades als substrats cel·lulòsics. La tècnica també s’ha assajat emprant diverses lacases.
S’han utilitzat diverses tècniques d’anàlisi per estudiar els mecanismes de reacció, i les interaccions FS-substrat. Les tècniques han estat: DLS, QCM, FTIR, espectroscopia UVVIS, potencial-Z, Turbiscan® i Voltametria Cíclica. S’ha proposat l’estructura química de les molècules resultants de l’oxidació del LG, els possibles mecanismes d'oxidació, i possibles mecanismes d'empelt entre els compostos modificats i la cel·lulosa. També s’ha analitzat l'efecte de la longitud de la cadena alquílica i dels tractaments tèrmics en les propietats antioxidant i hidrofòbica.
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Removal of boron from aqueous solutions using biopolymers and compositesDemey Cedeño, Hary 25 November 2014 (has links)
Tesi per compendi de publicacions. La consulta íntegra de la tesi, inclosos els articles no comunicats públicament per drets d'autor, es pot realitzar prèvia petició a l'Arxiu de la UPC / The growing concern over environmental pollution in recent decades has placed increasing focus on research into the development of sustainable processes associated with the removal of contaminants in waters. Water is scarcer than three decades ago, and there is still no satisfactory solution for the removal of pollutants.
One element that has gained worldwide prominence is boron. Although it is a nutrient needed in small amounts for human and plant metabolism, higher levels are toxic to most plants and are associated with reproductive problems in humans. The World Health Organization (WHO) suggests a maximum concentration in drinking water of 2.4 mg/L, but many countries have not yet adopted this recommendation in their water treatment controls.
At present, there is no general method for boron removal; several techniques can be used, such as electrodialysis, precipitation, chemical coagulation and electrocoagulation, complexation/nanofiltration, phytoremediation, ion exchange, reverse osmosis and adsorption with different materials. The selection of a particular treatment technology should be made not only on the basis of its efficiency but also with consideration of the associated environmental and financial costs.
Biopolymers are a potential solution that has received little attention in the literature. Biopolymers and their derivatives are diverse and abundant in nature; they exhibit fascinating properties and are increasingly important in many applications thanks to their environmentally-friendly characteristics. A small number of publications report the possibility of using tannin gel (Morisada et al., 2011), cellulose cotton (Liu et al., 2007) or chitosan modified with N-methy-D-glucamine (Sabarudin et al., 2005), sugars (Morisada et al., 2011) and diols (Oishi and Maehata, 2013; Fortuny et al., 2014). Biosorption is an effective, simple and cost-beneficial method for the removal of contaminants from waters.
This thesis focuses on the development of a sorption-based separation process, using biopolymers and composites for boron removal. The work has been carried out at the Department of Chemical Engineering of the Universitat Politècnica de Catalunya (UPC) in the framework of two research projects (Ref.: CTQ2008PPQ-00417/PPQ and CTQ2011PPQ-22412/PPQ) and the FPI fellowship (BES 2009-026847) financed by the Spanish Ministry of Science and Innovation (MICINN). This work is a continuation of research that has been underway at the Department of Chemical Engineering (UPC) for many years, on the development of advanced separation processes for the removal of valuable compounds or contaminants from aqueous solutions. It contributes to the state of the art on boron separation technologies (examples of which include the development of new composites based on the encapsulation of metal hydroxides in biopolymers).
Alginate and chitosan were effectively used as sorbents for boron recovery in the current research. Immobilization techniques were implemented using the technology described by Guibal et al., 2010; active materials are trapped in situ and distributed throughout the polymer support, creating a more stable adsorbent than those obtained by the traditional impregnation method, in which the active material is released partially from the pores of the polymer support while successive adsorption-desorption cycles are performed.
Three composite materials have been synthesized in order to improve the sorption capacity, the selectivity towards boron species, and the mechanical properties of the raw sorbents: calcium alginate/alumina (CAAl), which improves the sorption capacity of alginate in neutral medium; chitosan/nickel(II) hydroxide [chiNi(III)] and chitosan/Iron(III) hydroxide [chiFer(III)], which increase the sorption uptake of chitosan and improve the handling of hydroxides in the adsorption process, and are stable enough to be used in aggressive environments such as seawater without affecting sorption uptake. / La creciente preocupación por la contaminación del medio ambiente en las últimas décadas ha ocasionado un auge en la investigación de procesos sostenibles relacionados con la remoción de contaminantes de las aguas. El agua de consumo es más escasa que hace tres décadas, y aún no existe solución satisfactoria para la separación de ciertos contaminantes. Un elemento que ha ganado especial importancia en todo el mundo es el boro. Aunque es un nutriente necesario en pequeñas cantidades para el metabolismo de las plantas, los niveles altos son tóxicos para la mayoría de ellas y se asocian con problemas reproductivos en los seres humanos. La Organización Mundial de la Salud (OMS) sugiere una concentración máxima en el agua potable de 2.4 mg/L, pero muchos países aún no han adoptado esta recomendación en sus controles de tratamiento de agua. En la actualidad, no existe un método general para la separación del boro; varias técnicas pueden ser utilizadas, tales como electrodiálisis, precipitación, coagulación química, electrocoagulación, complejación/nanofiltración, fitorremediación, intercambio iónico, ósmosis inversa y adsorción con diferentes materiales. La selección de una tecnología de tratamiento específica, debe hacerse no sólo sobre la base de su eficacia, sino también con la consideración de los costos ambientales y financieros asociados. Los biopolímeros son una posible solución que ha recibido poca atención en la literatura de los últimos años. Los biopolímeros y sus derivados son diversos y abundantes en la naturaleza; exhiben propiedades fascinantes y son cada vez más importantes en muchas aplicaciones gracias a sus características ecológicas. Un pequeño número de publicaciones reportan la posibilidad de utilizar gel de tanino (Morisada et al., 2011), celulosa (Liu et al., 2007), quitosano modificado con N-metil-D-glucamina (Sabarudin et al., 2005), azúcares (Morisada et al., 2011) y dioles (Fortuny et al., 2014). La técnica de biosorción es eficaz, sencilla y económicamente beneficiosa para la remoción de contaminantes de las aguas. Esta tesis se centra en el desarrollo de un proceso de separación basado en la adsorción, mediante el uso de biopolímeros y composites para la remoción del boro. El trabajo se ha llevado a cabo en el Departamento de Ingeniería Química de la Universitat Politècnica de Catalunya en el marco de dos proyectos de investigación (Ref. CTQ2008PPQ-00417/PPQ y CTQ2011PPQ-22412/PPQ) y la beca FPI (BES 2009-026847) financiados por el MICINN-España. Este trabajo contribuye al estado del arte en tecnologías de separación de boro (ejemplos de los cuales incluyen el desarrollo de nuevos composites basados en la encapsulación de hidróxidos de metales en biopolímeros). En la presente investigación se utilizó el alginato y el quitosano como sorbentes y soportes poliméricos para la recuperación del boro. La técnica de inmovilización se ha desarrollado utilizando la tecnología descrita por Guibal et al., 2010; los materiales inorgánicos fueron encapsulados in-situ y distribuidos por toda la matriz polimérica, creando un adsorbente más estable que los obtenidos por el método tradicional de impregnación, en la que el material activo se libera parcialmente de los poros del soporte mientras se realizan los ciclos sucesivos de adsorción-desorción. Se han sintetizado tres materiales compuestos con el fin de mejorar la capacidad de sorción, la selectividad frente a las especies de boro, y las propiedades mecánicas de los sorbentes primarios: alginato de calcio/alúmina (CAAl), el cual mejora la capacidad de sorción del alginato en medio neutro; quitosano/hidróxido de níquel(II) [chiNi(III)] y quitosano/hidróxido de hierro(III) [chiFer(III)], los cuales mejoran la tasa de sorción del quitosano y contribuyen a mejorar el manejo de hidróxidos en el proceso de adsorción. Estos materiales son lo suficientemente estables para ser utilizados en ambientes agresivos como el agua de mar sin verse afectada su capacidad de adsorción.
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Safety life cycle analysis applied to the engineering of pressure relief valves in process plantsBasco Montia, Josep 01 February 2016 (has links)
Chemical plants and other industrial installations process and store hazardous materials, which represent a certain risk to people, equipment and the environment. Overpressure is one of the most common upsets in process plants and relief devices (pressure relief valves, rupture discs, overpressure-vacuum valves) are required on process equipment to prevent internal pressures from rising to levels, which could cause catastrophic equipment failure. They are the ultimate line of protection against equipment rupture and are therefore extremely critical safety elements. However, this criticality is not always accounted for in existing plants and in the engineering of new ones, as a lot of pressure relief systems audits performed recently, especially in US, have demonstrated. As an example, a 2014 report from Siemens Energy, Inc. of Houston, pointed out that, after performing 1,197 pressure relief systems audits between 2005 and 2014, consisting of 174,943 pieces of equipment and 80,372 pressure relief devices, 47% of the relief devices had a deficiency, e.g. 13,4% were undersized. In another statistical study focused on the maintenance process of pressure relief valves conducted in 1995 and based on 13,000 items inspected in the workshop, it was found that 18% of the valves only opened at a pressure higher than 110% of the set pressure and 3% did not open at a pressure of twice the set pressure.
Therefore, it is clear that a methodology for increasing the reliability of pressure relief devices would be very useful. A new methodology has been developed in this thesis based on an extension of the safety life cycle concept developed for the safety instrumented systems, according to the IEC 61511. This new methodology covers all the steps of the life cycle of a pressure relief valve: a) risk analysis; b) safety requirements specification; c) design; d) reception, installation and checking; e) operation, maintenance and revision; f) management of change; g) decommissioning h) verification and i) documentation and technical audits.
This methodology has been applied to three existing petrochemical plants, obtaining results that validate it as a useful tool in the target of increasing the reliability of pressure relief valves. / Les plantes químiques i altres instal·lacions industrials processen i emmagatzemen materials perillosos, els quals representen risc per les persones, per els equips i per el medi ambient. La sobrepressió es una de les pertorbacions mes freqüents en les plantes de procés i els dispositius d’alleugeriment de pressió (vàlvules de seguretat, discs de trencament, vàlvules de sobrepressió-buit) són necessaris per prevenir que les pressions internes dels equips a pressió arribin a nivells, que puguin ocasionar la ruptura catastròfica del mateix. Aquests dispositius són l’ultima capa de protecció abans de la ruptura del equip i són, per tant, elements de seguretat molt crítics. Malauradament, aquesta criticitat no se la te sempre en compte en les plantes existents, ni tampoc en la enginyeria i construcció de plantes noves, com moltes auditories de sistemes d’alleugeriment de pressió realitzades recentment, especialment als Estats Units, han demostrat. Per exemple, un informe de Siemens Energy, Inc. de Houston del any 2014, indicava que després de haver realitzat 1197 auditories dels sistemes d'alleugeriment de pressió entre l'any 2005 i 2014, consistint en 174943 equips i 80373 dispositius d’alleugeriment de pressió, un 47% dels dispositius tenien una deficiència, per exemple, 13,4% estaven subdimensionats. En un altre estudi estadístic focalitzat en el manteniment de vàlvules de seguretat realitzat a l’any 1995 i basat en 13000 vàlvules inspeccionades al taller, es va trobar que el 18 % nomes obrien a una pressió mes alta que el 110% de la pressió de tarat i un 3% no obrien ni a una pressió del doble de la tarat. En conseqüència, esta clar que una metodologia per incrementar la fiabilitat dels dispositius d'alleugeriment de pressió seria molt útil. Una nova metodologia s’ha desenvolupat en aquesta tesi basada en una extensió del concepte del cicle de vida de seguretat funcional desenvolupat originalment per els sistemes instrumentats de seguretat, d’acord amb la IEC 61511. Aquesta nova metodologia avarca totes les etapes del cicle de vida d’una vàlvula de seguretat: a) anàlisi del risc, b) especificació dels requisits de seguretat, c) disseny, d) recepció, instal·lació i comprovació, e) operació, manteniment i revisió, f) gestió del canvi, g) donar de baixa h) verificació i i) documentació i auditoria tècnica. Aquesta nova metodologia ha estat aplicada a tres plantes petroquímiques existents, obtenint resultats que la validen com una eina útil per l’objectiu de augmentar la fiabilitat de les vàlvules de seguretat
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Scaling-up methodology : a systematical procedure for qualifying NPP nodalizations. Application to the OECD/NEA ROSA-2 and PKL-2 Counterpart testMartínez Quiroga, Victor 17 November 2014 (has links)
System codes along with necessary nodalizations are valuable tools for thermal hydraulic safety analysis. Qualifying both codes and nodalizations is an essential step prior to their use in any significant study involving code calculations. Since most existing experimental data come from tests performed on the small scale, any qualification process must therefore address scale considerations.
Along these lines, the present thesis introduces a new scaling-up methodology that contributes to the qualification of Nuclear Power Plant (NPP) nodalizations by means of scale disquisitions. The "UPC Scaling-up methodology" is a systematic procedure based on the extrapolation of Integral Test Facility (ITF) post-test simulations. There are three main pillars that support this procedure: judicious selection of experimental transients, full confidence in the quality of the ITF simulations, and simplicity in justifying discrepancies that appear between ITF and NPP counterpart transients.
The techniques that are presented include the so-called Kv scaled calculations as well as the use of two new approaches, ¿Hybrid nodalizations¿ and "Scaled-up nodalizations". These latter two methods have revealed themselves to be very helpful in producing the required qualification and in promoting further improvements in nodalization. "Scaled-up nodalizations" allow effects of the ITF scaling-down criterion to be checked. On the other hand, "Hybrid nodalizations" help the user to establish how design differences modify the results. In order to carry out these calculations, a Powerto-Volume-Scaling Tool (PVST) was developed. This software generates scaled-up input decks for RELAP5mod3 following the Power to Volume Scaling (PtoV) methodology. Within the presentation of this software, it is included a detailed description of the PtoV criterion together with the scaling distortions that are expected from its application to the RELAP5mod3 equations. PVST capabilities are also assessed on two post-test simulations that were carried out at the LSTF experimental facility within the framework of the OECD/NEA ROSA and ROSA-2 projects.
Finally, an assessment of the present methodology was carried out by making use of the OECD/NEA ROSA-2 and PKL-2 Counterpart Tests (an exhaustive description of both facilities and experiments is also included). One of the limitations of scaling methodologies is the impossibility to qualify their predictions because of a lack of counterpart experimental data at NPP level. Thus, the ROSA-2 PKL-2 Counterpart Test was of great value because it allows an identical transient to be compared between two facilities with relevant differences in both design and scale. The study of both LSTF and PKL counterpart tests has enabled us to define which phenomena could be well reproduced by the nodalizations and which phenomena could not, and also to establish the basis for future extrapolation to a NPP scaled calculation. On the other hand, the application of the UPC scaling-up methodology has demonstrated the fact that selected phenomena can be scaled-up and explained between counterpart simulations by carefully considering differences in both scale and design.
As future lines of research, in the short term it is planned to fully apply the present methodology to qualify NPP nodalizations for the correlation of core exit temperatures (CET) versus peak cladding temperatures (PCT). In the long term, it is also intended to fully integrate the "UPC scaling-up methodology" within scaling issue, and to focus the efforts on providing a definite answer to the scaling controversy on the extrapolation of code accuracy to NPP level. / Los códigos de sistema, así como las nodalizaciones asociadas a sus cálculos, son herramientas de gran valor para los análisis de seguridad. La cualificación de ambos, códigos y nodalización, es un paso esencial antes de su uso en cualquier estudio significativo que involucre cálculos computacionales. Por otra parte, puesto que la mayoría de los datos experimentales existentes se obtienen de experimentos realizados en plantas a pequeña escala, cualquier proceso de cualificación necesita abordar el tema de la escalación. En este sentido, la presente tesis desarrolla una nueva metodología (UPC Scaling-up) que contribuye a cualificar las nodalizaciones de las centrales nucleares (NPP) por medio de análisis de escalación. Dicha metodología es un procedimiento sistemático basado en la extrapolación de los datos obtenidos en las simulaciones de experimentos realizados en plantas integrales (ITF). Tres son los pilares que lo sustentan: el juicio selectivo de los transitorios experimentales a analizar, la garantía absoluta de la calidad de sus simulaciones y la simplicidad a la hora de justificar las discrepancias que surjan entre la ITF y los transitorios equivalentes NPP. Las técnicas que se presentan a continuación incluyen los llamados cálculos Kv-scaled, así como el uso de dos nuevos conceptos, las nodalizaciones "híbridas" y "Scaled-up". Estos dos últimos métodos se han demostrado indispensables a la hora de cualificar y mejorar las nodalizaciones NPP. Los "Scaled-up" permiten al analista comprobar los efectos del criterio de escalación de la ITF en los resultados del experimento. Por otro lado, las cálculos "híbridos" ayudan a determinar cómo se modifican los resultados a consecuencia de las diferencias en el diseño. Para realizar estos cálculos, se ha creado un nuevo programa, el Power-to-Volume Scaling Tool (PVST). Este software genera inputs "Scaled-up" en RELAP5mod3 siguiendo el criterio de escalación Power to Volume (PtoV). Junto a la presentación de este software, se incluye una descripción detallada del PtoV así como las distorsiones de escala que se pueden esperar al aplicarlo en las ecuaciones del código. Las capacidades de PVST también se han evaluado mediante dos simulaciones pos-test que se llevaron a cabo en la planta experimental LSTF dentro de los proyectos OECD/NEA ROSA y ROSA-2. Por último, se incluye una evaluación de la metodología "UPC Scaling-up" a partir de los experimentos counterpart que se realizaron en el marco de los proyectos OECD/NEA ROSA-2 y PKL-2 (también se incluye una descripción exhaustiva de ambas instalaciones y experimentos). Una de las limitaciones de las metodologías de escala es la imposibilidad de cualificar sus predicciones debido a la falta datos experimentales análogos a nivel NPP. Es por ello que el experimento counterpart ROSA-2 PKL-2 resulta de gran valor, ya que permite comparar un transitorio de condiciones idénticas entre dos instalaciones con diferencias relevantes tanto en el diseño como en la escala. El estudio post-test de ambos experimentos, permitió determinar los fenómenos que el código podía simular así como las bases para una futura extrapolación a una nodalización de planta real. Por otro lado, la aplicación de la metodología "UPC scaling-up" demostró el hecho de que los fenómenos seleccionados son escalables y sus discrepancias se pueden explicar si se analizan de forma pormenorizada las diferencias tanto en la escala y como en el diseño. Como futuras líneas de investigación, a corto plazo se pretende aplicar de forma completa la presente metodología para cualificar nodalizaciones NPP en los fenómenos reportados en el experimento counterpart (temperaturas PCT/CET). A largo plazo, se tiene la intención de integrar plenamente la metodología "UPC Scaling-up" en la scaling issue, focalizando el trabajo en ofrecer una respuesta definitiva a la controversia de escala que existe sobre la extrapolación de la precisión de código a nivel NPP.
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Síntesis y caracterización de un nuevo polímero conductor basado en biimidazol para pilas de combustible de electrolito poliméricoOrtega Marín, María del Carmen 25 January 2016 (has links)
En esta tesis se sintetiza y caracteriza un nuevo polímero basado en el biimidazol, el poli[4-4'(p-fenilen)-2,2'bi-1H-imidazol] (PBII), con el objetivo de evaluar su viabilidad como polímero conductor en membranas de pilas de combustible de alta temperatura. En la memoria del trabajo de tesis se indican los principales puntos desarrollados, así como las conclusiones del estudio: 1. Se detallan las fases de la síntesis y se verifican cada una de ellas mediante las técnicas de resonancia magnética nuclear o espectroscopía de infrarrojos. 2. Se caracteriza el polímero sintetizado mediante la aplicación de las técnicas de análisis elemental, termogravimetría, espectroscopia de infrarrojos, viscosidad intrínseca, cromatografía de exclusión molecular y se mide la conductividad mediante el método de las dos puntas. Los análisis realizados validan las características del PBII para su uso como polímero en membranas conductoras de protones y ponen de manifiesto que el PBII mejora la conductividad presentada por el ABPBI y el PBI, manteniendo una estabilidad térmica similar a dichos polímeros. 3. Se realizan membranas poliméricas basadas en PBII que se caracterizan mediante la técnica de microscopía electrónica de barrido y se utiliza el método de cuatro puntas para la medición de la conductividad. El estudio morfológico de la membrana muestra una superficie homogénea y sin porosidad. Adicionalmente, los resultados obtenidos en la conductividad permiten afirmar que las membranas basadas en PBII presentan un valor de conductividad más elevado que las de ABPBI y PBI. A modo de conclusión final puede decirse que la presente tesis aporta un nuevo polímero conductor, el poli[4-4'(pfenilen)-2,2'bi-1H-imidazol] (PBII), para la realización de membranas poliméricas en pilas de combustible. El PBII presenta mejores características de conductividad que el ABPBI y el PBI, manteniendo propiedades similares en cuanto a estabilidad térmica se refiere. Este trabajo ha permitido validar la potencialidad de los polímeros PBII en aplicaciones que serán cada vez más importantes como son las pilas de combustible de electrolito polímerico de alta temperatura. / This thesis synthesizes and characterizes a novel polymer based on biimidazole, the poly[4-4'(p-phenilen)-2,2'bi-1Himidazole](PBII), with the aim of evaluate its feasibility as conducting polymer in high temperature fuel cell membranes. The main carried out steps can be found in the PhD dissertation and the main conclusions are given in the following:
1. The synthetic pathway is detailed in the thesis and is validated by means of nuclear magnetic resonance or infrared spectroscopy.
2. The synthesized polymer is subsequently characterized by applying the techniques of elemental analysis, thermogravimetric analysis, infrared spectroscopy, intrinsic viscosity, gel permeation chromatography and the conductivity is measured by means of the two point probe method. The analysis validate the PBII characteristics for being used as polymer in proton conducting membranes and point out that the PBII improves the conductivity presented by the ABPBI and the PBI with a similar thermal stability.
3. Polymeric membranes based on PBII are developed and characterized by means of scanning electron microscope. The morphology study shows a homogeneous membrane surface without any porosity. The conductivity is measured by applying the four point probe method. The conductivity results of the PBII membranes are higher than the ones obtained with the ABPBI and PBI membranes.
In conclusion this PhD dissertation presents a novel conducting polymer, the poly[4-4'(p-phenilen)-2,2'bi-1H-imidazole](PBII), to be used in the development of proton conducting fuel cell membranes. The PBII shows better conducting characteristics than the ABPBI and the PBI keeping similar thermal stability properties. This work validates the potentiality of the PBII polymers in applications that are becoming more important such as the high temperature polymer electrolite fuel cells.
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Comprehensive inventories for Life Cicle Assessment in urban wastewater systemsMorera Carbonell, Sadurní 19 February 2016 (has links)
This thesis represents an important contribution to facilitate the efficient creation of detailed inventories to carry out Life Cycle Assessment (LCA) studies of urban wastewater systems. Specifically, this thesis provides a tool to carry out an evaluation of the environmental impact of the construction of sewer systems. The work also shows that is necessary to consider the construction of wastewater treatment plants (WWTPs) when these studies are carried out and provides a set of useful linear regressions to calculate in a quickly and precise way the inventories for the civil works of small to medium WWTPs. Finally, the application of this methodology to evaluate the integrated management of different WWTPs is also presented together with an application of the water footprint in WWTPs to demonstrate that it can be also a valid tool to calculate its environmental impact. / Aquesta tesi representa una contribució important per facilitar la realització d'inventaris detallats per dur a terme estudis d'Anàlisi de Cicle de Vida (ACV) al sistema urbà d'aigua residual i que es poden obtenir d’una forma ràpida i amb resultats satisfactoris. Concretament, amb la tesi es presenta una eina per poder realitzar estudis d'impacte ambiental per la construcció de sistemes de col•lectors d'aigua residual. També demostra que cal tenir en compte la construcció de depuradores en aquest tipus d'estudis i també facilita una sèrie de regressions lineals útils per calcular de forma ràpida i precisa els inventaris per l’obra civil de depuradores d’una mida petita o mitjana. Finalment, també es presenta l'aplicació de la metodologia per avaluar la gestió integrada de diferents depuradores i l'aplicació de la petjada hídrica en depuradores per demostrar que també pot ser una eina molt vàlida per calcular d’una forma senzilla el seu impacte ambiental.
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Strategies to improve anaerobic digestion of wastes with especial attention to lignocellulosic substratesFonoll Almansa, Xavier 17 December 2015 (has links)
The energy demand increase and the generation of wastes is being the major problem regarding the next generation sustainability. Both problems can be corrected through the implementation of anaerobic digestion, a waste treatment technology able to produce electricity, heat and a fertilizer. The anaerobic co-digestion between two wastes with complementary characteristics has been widely studied to improve the methane production in anaerobic digesters. However, to increase the methane production from lignocelulosics substrates is still one of the main challenges of anaerobic digestion. Lignocelulosic components are a tridimensional structure between lignin, hemicellulose and cellulose, which bonds are extremely difficult to degrade by conventional anaerobic bacteria. Besides, those components can be found in a wide range of substrates such as municipal solid wastes, agro-wastes and energy crops.
In the following thesis, the increase of the economic viability of anaerobic digestion plants treating lignocelulosic materials has been studied.
Initially, the transitory state while the co-substrate was changed in the anaerobic co-digestion between sewage sludge and fruit waste was studied. The stability of the reactors was not drastically affected when the co-substrate was changed, but, the use of a co-substrate with a high concentration of fibers did not improve the methane production too much. Secondly, in order to consider the valorization of lignocellulosic components through the production of by-products, the effect of these components on the municipal solid wastes anaerobic digestion performance was evaluated. When the paper waste was removed, the biodegradability of the feedstock increased allowing the specific methane production to increase. Nevertheless, the digester was more fragile against instabilities and the digestate quality decreased if short retention times are applied. Next, low-temperature and ultrasounds pretreatments, strategies that have not been used too much for the degradation of lignocellulosic components, were studied to increase the methane production during the anaerobic co-digestion of barley waste and pig manure. Low-temperature and ultrasound pretreatment increased the methane production in a 27 and 12% respectively but only the first one had a positive energy balance. Finally, rumen, a waste from the slaughterhouse industry was used as inoculum and as co-substrate to bring hydrolytic bacteria able to improve the degradation of Napier grass. The results showed that, when rumen is used as inoculum it need to be mixed with an inoculum with high buffer capacity and a co-substrate with alkalinity need to be used to avoid long start-up periods. The methane production only increased at the beginning and in a long-term, the microbial community was governed by the substrate and not by the rumen. However, rumen did not increase the methane production when it was used as a co-substrate because the digester conditions were not optimal for the activity of hydrolytic bacteria. All the experiments were carried out in the laboratory and the conclusions are considered a progress for the energy production through the use of lignocellulosic substrates. / El incremento de la demanda energética y la consecuente generación de residuos ponen en peligro la sostenibilidad del futuro. Es por eso que la digestión anaeróbica resulta ser una solución factible para mitigar el problema ya que se puede generar electricidad, calor y fertilizante a partir de los residuos orgánicos. El incremento de la producción de metano se consiguió a partir de la co-digestión de residuos con características complementarias. Aun así, no siempre se consigue extraer todo el potencial metanogénico de los residuos, especialmente, en el caso de los sustratos ligno-celulósicos. Los compuestos ligno¬celulósicos son estructuras complejos entre la lignina, la hemicelulosa y la celulosa con enlaces resistentes a la degradación microbiana que se encuentran en los residuos agro-industriales, los residuos municipales y los cultivos energéticos.
En la tesis, se ha buscado aumentar la viabilidad económica de las plantas de digestión anaeróbica que tratan residuos con componentes ligno-celulósicos. Se usaron distintas nuevas estrategias para aumentar la degradabilidad de la materia ligno-celulósica como los pretratamientos térmicos de baja temperatura y de ultrasonidos y la integración del rumen, un residuo de la industria cárnica, para aportar bacterias hidrolíticas. Para valorar la opción de separar estos componentes para la formación de sub-productos, se estudió su efecto sobre el rendimiento del digestor en términos de estabilidad, producción de metano y calidad del digerido para así poder implementar la producción se sub-productos.
Los estudios realizados en esta tesis doctoral se llevaron a cabo a escala de laboratorio y las conclusiones han supuesto un avance para el aprovechamiento energético de los residuos ligno-celulósicos en el futuro.
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Catalytic hydrogen production over RhPd/CeO2 catalysts and CO purification over Au/TiO2 catalystsJiménez Divins, Núria 10 April 2015 (has links)
La consulta íntegra de la tesi, inclosos els articles no comunicats públicament per drets d'autor, es pot realitzar prèvia petició a l'Arxiu UPC / This Thesis focuses on the study of the catalytic production of hydrogen from a biofuel, namely the bioethanol. It also studies the subsequent purification of pre-cleaned reformate streams. The end use of the hydrogen produced is to feed fuel cells to power portable and mobile applications. In this Thesis, two types of catalysts have been developed. One consisting of RhPd/CeO2 catalysts aimed at generating hydrogen via the ethanol steam reforming. On the other hand, Au/TiO2 catalysts have been investigated to eliminate carbon monoxide from reformate streams. The developed catalysts have been tested under practical operational conditions. The developed catalysts have been characterized ex situ, in situ and under reaction conditions. The operando studies allowed for the investigation of the reorganization of the metals driven by the reactive atmosphere. Finally, the miniaturization of the hydrogen production and purification scale has been investigated. To achieve this goal, the developed catalysts have been implemented on microreactors composed of channels measuring only few microns. / A la present Tesi doctoral s'estudien la producció catalítica d'hidrogen a partir d'un biocombustible, el bioetanol, i la seva posterior purificació per alimentar piles de combustible que proporcionin energia a aplicacions portàtils i mòbils.
S'han desenvolupat dues famílies de catalitzadors, una de RhPd/CeO2 per generar hidrogen a partir de la reformació amb vapor d'etanol, i l'altra d'Au/TiO2 per eliminar el monòxid de carboni dels corrents de reformació pre-purificats. Els catalitzadors han estats estudiats en condicions de reacció properes a la indústria.
En aquesta tesi s'han caracteritzat els catalitzadors ex situ, in situ i també en condicions “operando” o de reacció. L'estudi en “operando” dels catalitzadors ha permès investigar la reorganització induïda pels reactius dels components del catalitzador.
Finalment, també s'ha estudiat la miniaturització tant del sistema de generació com de purificació de l'hidrogen per tal d'alimentar aplicacions de petit consum. Per això, s'han utilitzat microreactors composats de canals en l'escala del micròmetre.
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The Bioconversion of Plastic MaterialsStubblefield, Bryan 09 May 2016 (has links)
Plastics are highly useful economically because of their resistance to diverse types of environmental and chemical agents and their ability to be molded into many types of products. Globally, plastic production is greater than 20 million metric tons per year. However, their widespread use and often their disposable nature results in significant plastic accumulation in the environment. Plastics are made of hydrocarbons, materials that are biodegradable depending on their molecular structure and size. It is hypothesized that pre-treatment of plastic materials could enhance their bioavailability, facilitating their microbial biodegradation. In this dissertation, a process was developed to treat nylon 6,6 polymers by acid hydrolysis to produce a microbial growth medium. The chemical composition of the medium was determined by low pressure liquid chromatography-spectrophotometry and electrospray ionization mass spectrometry and found that the medium was a mixture of molecules with molecular weight > 800 m/z and with similar chemical characteristics to polyamines. There was steady growth of Pseudomonas putida KT2440 in the medium with concomitant substrate biodegradation. Notably, the yeast Yarowia lipolytica grew well in the medium when supplemented with yeast extract. A similar medium derived from nylon 6,6 containing nylon-derived particles supported the growth of Beijerinckia sp. and Streptomyces sp. BAS1. Confocal laser scanning microscopy and flame ionization gas chromatography were used to identify and quantify the production of polyhydroxybutyrate, a type of “bioplastic”. The aforementioned microorganisms were cultivated in a bench-scale bioreactor that was developed as part of this dissertation. The bioreactor had a novel impeller design resulting in enhanced mixing and rotation and also a modular format allowing for diverse configurations. The bioreactor was notable for its durability and low cost. A detailed description of its design is included in the appendices. In summary, plastic materials can potentially be processed into growth media for microorganisms and can be used for production of value-added products. The media described herein can be used in bioconversion processes using a bioreactor.
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Effect of ultrasound, low-temperature thermal and alkali treatments on physicochemical and biological properties of waste activated sludgeRuiz Hernando, María 17 June 2015 (has links)
The development of treatment processes to reduce or reuse sewage sludge is crucial for a proper environmental management. Segregating primary from secondary sludge allows for better reuse of secondary sludge, since digested secondary sludge is better suited for agricultural application, containing about double concentration in nutrients but significantly less contaminants. However, secondary sludge (also called waste activated sludge (WAS)) is difficult to dewater compared with primary sludge due to the existence of colloidal materials and extracellular polymeric substances (EPSs), which strongly retain water. WAS is also more difficult to digest under anaerobic conditions due to the presence of glycan strands in microbial cell walls. The low dewaterability and digestibility of WAS can be improved by applying treatments, which can partially disintegrate the WAS by disrupting flocs and cells and solubilising the EPSs. The treatments studied in this thesis were ultrasound, low-temperature thermal and alkali with NaOH. Specifically, it has been analysed the effect of the aforementioned treatment on WAS rheology, dewatering, hygienisation and anaerobic digestion. Rheology is the study of stress-strain relationships of viscoelastic materials. All the sludges analysed (untreated and treated) behaved as non-Newtonian pseudoplastic fluids, which indicates that the viscosity decreases with the applied shear rate. The sludges were also thixotropic (showing a hysteresis area in the plot of stress versus shear rate), which means that the viscosity is time dependent. The three aforementioned treatments resulted in the reduction of the steady state viscosity and the hysteresis area. Complementarily, a rheological structural model was proposed to examine the variations in the thixotropic behaviour of WAS after the application of the treatments. Sludge dewatering is essential to obtain a product dry enough to allow a reduction in storage volume. The three conditions of the thermal treatment (60, 80 and 90 ºC; 1 h, including the heating time to reach the temperature) and the higher intensities of ultrasound (27,000 kJ/kg TS) and alkali (157 g NaOH/kg TS) treatments improved sludge dewatering by centrifugation. To further evaluate the effect of treatments on the sludge dewatering, the EPSs contained in sludge were extracted and characterised. The EPSs were fractionated to generate two different EPS fractions: loosely bound EPSs (LB-EPSs) and tightly bound EPSs (TB-EPSs), where the latter is the innermost fraction and harder to release. An analysis of the untreated sludge revealed that the proteins, followed by the humic acids and polysaccharides, were the major constituents of the EPSs. Each of these components was primarily observed in the TB-EPS fraction. The treatments, particularly the alkali treatment, thoroughly solubilised the EPS, as indicated by the increase in the TOC, protein, humic acid and polysaccharide contents in the LB-EPS fraction. As a result, the dewaterability of WAS was improved. Hygienisation of the sludge is of uttermost importance if the sludge is intended for agriculture. The level of hygienisation was evaluated using three indicator organisms: Escherichia coli, somatic coliphages (SOMCPH) and spores of sulfite-reducing clostridia (SSRC). The thermal treatment at 80 ºC and the alkali treatment at 157 g NaOH kg TS allowed the hygienisation of the sludge, thus satisfying normal levels accepted by the EPA and the 3rd official draft from the EU. Conversely, the conditions tested for the ultrasound treatment barely reduced the levels of microbial indicators. Mesophilic anaerobic digestion is a widely used method to stabilise the sludge. The alkali pre-treatment (157 g NaOH/kg TS) exhibited the greatest methane production increase (34%) followed by the ultrasonication (27,000 kJ/kg TS; 13%), whereas the thermal pre-treatment (80 ºC, 15 min) presented a methane potential similar to the untreated sludge. However, the use of NaOH as a pre-treatment is rather limited because of the rising sodium concentration in the digester. / El desarrollo de procesos para la reducción o reutilización de los lodos resulta determinante para una apropiada gestión medioambiental. Tratando por separado el lodo activado del primario (y no la mezcla como suele hacerse) se favorece el uso del lodo activado en agricultura tras su digestión, ya que el lodo activado contiene el doble de nutrientes y menor carga contaminante que el primario. No obstante, el lodo activado (también denominado lodo secundario o biológico) es más difícil de deshidratar que el primario, ya que presenta una estructura interna organizada de flóculos unidos por las sustancias poliméricas extracelulares (EPSs, por sus siglas en inglés), las cuales atrapan el agua. En este contexto, la reología, que es la ciencia que estudia las relaciones entre la fuerza y la deformación de los materiales, es una herramienta muy útil para la caracterización de la viscosidad o estructura interna de los lodos. El lodo activado es también más difícil de digerir anaeróbicamente debido a las cadenas de glicanos presentes en las paredes celulares de las bacterias. En resumen, para poder deshidratar y digerir un lodo activado será necesario acondicionarlo previamente mediante tratamientos, con el fin de solubilizar las EPSs y aumentar su biodegradabilidad. Si además el lodo quiere destinarse a agricultura deberá estar higienizado. En esta tesis se ha estudiado el efecto de tres tratamientos (ultrasonido, térmico a baja temperatura y alcalino con NaOH) sobre la reología, deshidratación, higienización y digestión anaerobia de lodos activados. Los tres tratamientos redujeron considerablemente la viscosidad del lodo debido a la solubilización de la las EPSs. Así mismo, la solubilización de la EPSs facilitó la expulsión del agua confinada dentro de los flóculos del lodo, mejorando la deshidratación mediante centrifugación. El tratamiento alcalino con dosis de NaOH elevadas fue el que más EPSs solubilizó, de manera que fue el que permitió extraer más agua y el que más aumentó la producción de metano, además de higienizar el lodo. No obstante, este tratamiento tiene el inconveniente de incrementar la concentración de sodio en el digestor, lo cual podría llegar a inhibir el proceso de digestión. Los ultrasonidos redujeron notablemente la viscosidad, además de mejorar la deshidratación y la digestión del lodo. Sin embargo, este tratamiento no fue capaz de higienizar el lodo. El tratamiento térmico a baja temperatura aumentó muy ligeramente la producción de metano (posiblemente debido al corto tiempo de exposición) y permitió deshidratar e higienizar el lodo.
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