Characterization of microplastics and natural gas by infrared spectrometry and multivariate modelling

Programa Oficial de Doutoramento en Ciencia e Tecnoloxía Ambiental. 5006V01[Abstract] The main objective of this work is to explore the use of infrared spectrometry combined with the application of multivariate chemometric models to the quantification of the major components of natural gas and to the identification of plastic samples, both artificially aged and collected from coastal ecosystems. The articles presented here deal with different themes related with these topics. In particular: the application of IR-inert gases to improve the spectra of other gases of interest; a report evidencing a general absence of important specifications of the instrumental setup of environmental studies on microplastics, suggesting a minimum of information to be offered; and a study of the effects of aging in both the surface morphology and the spectral characteristics of polyamide 6.6. Finally, chemometric models have been developed to identify the main constituent polymers of microplastics and to quantify the major components of natural gas samples, as well as their Wobbe index.[Resumen] El principal objetivo de este trabajo es explorar el uso de la espectrometría infrarroja combinada con la aplicación de modelos quimiométricos multivariables para cuantificar de la composición mayoritaria de muestras de gas natural y para identificar muestras de plásticos, tanto envejecidos de forma artificial como recolectados de ecosistemas costeros. Los artículos presentados tratan sobre diversos aspectos relacionados con estos temas. En concreto: el uso de gases inertes a la radiación infrarroja para mejorar los espectros de otros gases de interés; un informe que evidenciando una importante ausencia de especificaciones instrumentales básicas en los estudios medioambientales sobre microplásticos, donde se sugiriere un mínimo de información a aportar; y un estudio de los efectos del envejecimiento en la morfología y características espectrales de la poliamida 6.6. Finalmente, se han desarrollado modelos quimiométricos capaces de identificar los principales polímeros constituyentes de microplásticos y de cuantificar los componentes mayoritarios de muestras de gas natural, así como su índice Wobbe.[Resumo] O obxectivo principal deste traballo é explorar o uso da espectrometría infravermella combinada coa aplicación de modelos quimiométricos multivariabeis para a cuantificación da composición maioritaria de mostras de gas natural e a identificación de plástico, tanto envellecidos artificialmente como recollido de ecosistemas costeiros. Os diferentes artigos presentados tratan diversos aspectos relacionados con estes temas. Nomeadamente: a aplicación de gases inertes á radiación infravermella para mellorar os espectros doutros gases de interese; unha recompilación onde se constata a ausencia xeral especificacións instrumentais fundamentais nos estudos medioambientais de microplásticos, suxerindo un mínimo de información a aportar; e un estudo dos efectos do envellecemento na morfoloxía e características espectrais na poliamida 6.6. Finalmente, desenvolvéronse modelos quimiométricos capaces de identificar os polímeros constituíntes de microplásticos e de cuantificar os principais compoñentes de mostras de gas natural, ademais do seu índice de Wobbe

Factor screening study affecting alkylphenol extraction in seaweeds by hot water extraction (PHWE)

[Resumen] El objetivo del presente trabajo es el estudio de la extracción de algunos de los alquilfenoles más comercializados (4-octilfenol, 4-terc-octilfenol y nonilfenol) y bisfenol A mediante agua a presión sobrecalentada (PHWE) en algas marinas comestibles comerciales y su posterior análisis mediante cromatografía de líquidos de alta resolución acoplado a espectrometría de masas (HPLC-MS/MS). Se ha utilizado un diseño de experiencias Plackett-Burman para averiguar las variables que afectan de forma más significativa a la extracción. Se estudiaran como posibles variables la temperatura, presión, tiempo y ciclos de extracción, ratio dispersante(C18)-muestra, concentración de modificador (MeOH) y tiempo de purga. La importancia de cada variable se verá representada mediante cartas Pareto de primer orden. Según los resultados obtenidos, excepto la presión, todas las demás variables han resultado significativas.[Resumo] O obxetivo do presente traballo é a estudo da extracción dalguns dos alquilfenois mais comercializados (4-octilfenol, 4-terc-octilfenol e nonilfenol) e bisfenol A mediante auga a presión sobrequentada (PHWE) en algas mariñas comestibles comerciales e o seu posterior análise das mediante unha cromatografía de líquidos de alta resolución acoplada a espectroscopía de masas (HPLC-MS/MS). Utilizouse un deseño de experiencias Plackett-Burman para averiguar as variables que afectan de forma máis significativa á extracción. Estudiaranse como posibles variables a temperatura, presión, tempo e ciclos de extracción, ratio dispersante(C18)-mostra, concentración de modificador (MeOH) e tempo de purga. A importancia de cada variable verase representada mediante cartas Pareto de primer orde.. Según os resultados obtidos, excepto a presion, todalas demais variables resultaron significativas.[Abstract] The aim of this study is to analyze the extraction of some of the most commercialized alkyphenolic compounds (4-octylphenol, 4-terc-octylphenol and nonylphenol) and bisphenol A by pressurized hot water extraction (PHWE) on commercial edible seaweed and the analysis was performed using a high performance liquid chromatography (HPLC) coupled to mass spectrometry. A Placket-Burman experimental design was used to find the significant variables involved in the extraction. The potentially significant variables are temperature, pressure, time, extraction time and cycles, dispersant(C18)-sample ratio, modifier concentration (MeOH) and purge time. The importance of each variable will studied by first order Pareto charts. The results show that, except pressure, every variable is significative.Traballo fin de grao (UDC.CIE). Química. Curso 2014/201

Síntesis, caracterización y propiedades dieléctricas de perovskitas hibridas de interés fotovoltaico

Traballo fin de mestrado (UDC.CIE). Investigación química y química industrial. Curso 2016/2017[Resumen] Durante los últimos años las perovskitas híbridas inorgánica-orgánicas, que combinan componentes de naturaleza inorgánica e orgánica, despertaron un gran interés debido a sus interesantes propiedades, como por ejemplo, propiedades magnéticas, dieléctricas, multiferroicas, fotovoltaicas, etc. Este trabajo centrase na síntesis, caracterización y estudio de propiedades dieléctricas e conductividad eléctrica das perovskitas híbridas MAPbBr3 e EAPbI3, donde MA es metilamina EA es etilamina. Estos materiales tienen interés en el campo de los materiales fotovoltaicos y también en el campo de nuevos materiales dieléctricos. En este trabajo se realizó un estudio del efecto de la humedad sobre las propiedades dieléctricas y la conductividad dieléctrica del compuesto MAPbBr3. Los estudios realizados indican que una cantidad moderada de humedad provoca un aumento de la constante dieléctrica y de la conductividad de este material. Este último aspecto, es muy importante ya que esto favorece la eficiencia das celdas fotovoltaicas basadas en este material. Por otra parte, el compuesto EAPbI3 presenta una transición dieléctrica a temperaturas próximas a temperatura ambiente, posiblemente relacionada con una transición estructural de orden-desorden.[Abstract] Recently, organic-inorganic hybrid perovskites, which combine organic and inorganic components, showed great interest due to its interesting properties as, for example magnetic, dielectric, multiferroic, photovoltaic… This job is focused in the synthesis, characterization and study of the dielectric properties and electric conductivity of hybrid perovskites MAPbBr3 and EAPbI3, where MA is methylamine and EA ethylamine. This materials have great interest in the field of photovoltaic materials and in the field of new dielectric materials. In this work a study on the effect of humidity on the dielectric properties and conductivity of MAPbBr3 was performed. Studies show that a moderate quantity of humidity provokes an increase in the dielectric constant and conductivity of this material. This last aspect is very important, because this favors the efficiency of the photovoltaic cells based on this material. On the other hand, the compound EAPbI3 shows a dielectric transition at temperatures near room temperature, possibly related to an order-disorder structural transition.[Resumo] Durante os últimos anos as perovskitas híbridas inorgánica-orgánicas, que combinan compoñentes de natureza inorgánica e orgánica, espertaron un gran interese debida a súa interesantes propiedades, como por exemplo, propiedades magnéticas, dieléctricas, multiferroicas, fotovoltaicas, etc. Este traballo centrase na síntese, caracterización e estudo de propiedades dieléctricas e condutividade eléctrica das perovskitas híbridas MAPbBr3 e EAPbI3, onde MA é metilamina EA é etilamina. Estes materiais teñen de interese no campo dos materiais fotovoltaicos e tamén no campo de novos materiais dieléctricos. Neste traballo realizou un estudo do efecto da humidade sobre as propiedades dieléctricas e a condutividade dieléctrica do composto MAPbBr3. Os estudos realizados indican que unha cantidade moderada de humidade provoca un aumento da constante dieléctrica e da condutividade deste material. Este último aspecto, é moi importante xa que isto favorece a eficiencia das celas fotovoltaicas baseadas neste material. Por outra parte, o composto EAPbI3 presenta unha transición dieléctrica a temperaturas próximas a temperatura ambiente, posiblemente relacionada cunha transición estrutural de orde-desorde

Soluciones Flotante para Aerogeneradores: Plataforma Spar

La calidad del recurso eólico en alta mar, el crecimiento de la industria eólica, el desarrollo sostenible además de otros factores extrínsecos, tales como los riesgos de las centrales nucleares, la vulnerabilidad de los mercados ante crisis en países productores de petróleo y las altas emisiones de CO2 por parte de las centrales de ciclo combinado son algunos de los factores que, cada vez más, justifican la adopción de soluciones sostenibles de origen renovable donde la energía eólica flotante presenta un futuro prometedor. Las plataformas Spar son una de las posibles opciones. En el presente trabajo se muestra un procedimiento metódico de diseño de una plataforma Spar analizando las ventajas y los inconvenientes de este tipo de estructuras para lograr el cometido de soportar un aerogenerador de gran potencia en mar abiert

New Ways for the Advanced Quality Control of Liquefied Natural Gas

[Abstract] Currently, gas chromatography is the most common analytical technique for natural gas (NG) analysis as it offers very precise results, with very low limits of detection and quantification. However, it has several drawbacks, such as low turnaround times and high cost per analysis, as well as difficulties for on-line implementation. With NG applications rising, mostly thanks to its reduced gaseous emissions in comparison with other fossil fuels, the necessity for more versatile, fast, and economic analytical methods has augmented. This work summarizes the latest advances to determine the composition and physico-chemical properties of regasified liquid natural gas, focusing on infrared spectroscopy-based techniques, as well as on data processing (chemometric techniques), necessary to obtain adequate predictions of NG properties.Part of this work was performed under the EMPIR 16ENG09 project ‘Metrological support for LNG and LBG as transport fuel (LNG III)’. This project has received funding from the EMPIR programme co-financed by the Participant States and from the European Union’s Horizon 2020 Research and Innovation programme. Mestrelab, Reganosa and Naturgy are acknowledged for hiring the services of the Group of Applied Analytical Chemistry for FTIR method development. The Program “Consolidación e Estructuración de Unidades de Investigación Competitivas” of the Galician Government (Xunta de Galicia) is also acknowledged (Grant ED431C 2021/56).Xunta de Galicia; ED431C 2021/5

Monitorization of Polyamide Microplastics Weathering Using Attenuated Total Reflectance and Microreflectance Infrared Spectrometry

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] The EU goal to reduce marine plastic litter by ca. 30% by 2020 stressed the need to deploy analytical methods to ascertain the polymeric nature of a residue. Furthermore, as plastics age under natural conditions and usual databases do not include their weathered spectra, (micro)plastics in environmental samples may be unidentified. In this paper, polyamide (nylon) microplastics weathering was monitored because of its ubiquity in household commodities, clothes, fishery items and industry, whose residues end up frequently in the environment. Infrared spectra (ATR and microreflectance) and Scanning Electron Microscopy (SEM) images were collected periodically while exposing nylon to controlled weathering. It was seen that ATR was more sensitive than microreflectance to monitor the structural evolution of polyamide and that the spectra and the surface of weathered microplastics showed remarkable differences with the pristine material, which stresses the need for considering its evolution when identifying microplastics in environmental studies. The evolution of six band ratios related to the chemical evolution of this polymer are presented. SEM images revealed the formation of secondary microplastics at the most advanced weathering stages of polyamide.This work was supported through the JPI-Oceans BASEMAN and MicroplastiX projects, sponsored by the Spanish Ministry of Science and Innovation (Agencia Estatal de Investigación) -partially financed by the European Regional Development Fund program- (Grants: PCIN-2015-170-C02-01; PCIN- PCI2020-112145 and CTM2016-77945-C3-3-R, ARPA-ACUA). The Program ‘Consolidación e Estructuración de Unidades de Investigación Competitiva’ of the Galician Government (Xunta de Galicia) is also acknowledged (Grant: ED431C-2017/28)Xunta de Galicia; ED431C-2017/2

Supercapacitor Electro-Mathematical And Machine Learning Modelling For Low Power Applications

Low power electronic systems, whenever feasible, use supercapacitors to store energy instead of batteries due to their fast charging capability, low maintenance and low environmental footprint. To decide if supercapacitors are feasible requires characterising their behaviour and performance for the load profiles and conditions of the target. Traditional supercapacitor models are electromechanical, require complex equations and knowledge of the physics and chemical processes involved. Models based on equivalent circuits and mathematical equations are less complex and could provide enough accuracy. The present work uses the latter techniques to characterize supercapacitors. The data required to parametrize the mathematical model is obtained through tests that provide the capacitors charge and discharge profiles under different conditions. The parameters identified are life cycle, voltage, time, temperature, moisture, Equivalent Series Resistance (ESR) and leakage resistance. The accuracy of this electro-mathematical model is improved with a remodelling based on artificial neuronal networks. The experimental data and the results obtained with both models are compared to verify and weigh their accuracy. Results show that the models presented determine the behaviour of supercapacitors with similar accuracy and less complexity than electromechanical ones, thus, helping scaling low power systems for given conditions

Photovoltaic Energy Harvesting System Adapted for Different Environmental Operation Conditions: Analysis, Modeling, Simulation and Selection of Devices

The present research work proposes a photovoltaic energy harvester and an appropriate direct current (DC)/DC converter for a harvesting system after the study of the devices and taking the operation conditions. Parameters such as power, efficiency and voltage are taken into account under different environment conditions of illumination and temperature in order to obtain the best possible response. For this reason, suitable metal-oxide semiconductor field-effect transistor (MOSFET), diode, coil, frequency, duty-cycle and load are selected and analyzed for a DC/DC converter with boost architecture.This work has been supported by IK4-TEKNIKER research institute own funds and the joint work of Electronics and Communications and Intelligent Information System units and by the Department of Education of the Basque Government within the fund for research groups of the Basque university system [IT978-16]

Weathering-Independent Differentiation of Microplastic Polymers by Reflectance IR Spectrometry and Pattern Recognition

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] The presence and effects of microplastics in the environment is being continuously studied, so the need for a reliable approach to ascertain the polymer/s constituting them has increased. To characterize them, infrared (IR) spectrometry is commonly applied, either reflectance or attenuated total reflectance (ATR). A common problem when considering field samples is their weathering and biofouling, which modify their spectra. Hence, relying on spectral matching between the unknown spectrum and spectral databases is largely defective. In this paper, the use of IR spectra combined with pattern recognition techniques (principal components analysis, classification and regression trees and support vector classification) is explored first time to identify a collection of typical polymers regardless of their ageing. Results show that it is possible to identify them using a reduced suite of spectral wavenumbers with coherent chemical meaning. The models were validated using two datasets containing artificially weathered polymers and field samples.This work was supported by the EU Horizon2020-JPI Oceans Project “LAnd-Based Solutions for PLAstics in the Sea” (Grant No. 101003954, LABPLAS), and the “Integrated approach on the fate of MicroPlastics towards healthy marine ecosystems” (MicroplastiX, Grant PCI2020-112145, supported by the JPI Oceans Program and by Spanish Government, MCIN/AEI/10.13039/501100011033 and the European Union “Next Generation EU/PRTR program”). The Galician Government (‘Xunta of Galicia’) is acknowledged for its support to the QANAP group (Programa de Consolidación y Estructuración de Unidades de Investigación Competitiva. Ref. ED431C 2021/56). Funding for open Access charge: Universidade da Coruña/CISUGXunta de Galicia; ED431C 2021/5