Modification of porous nickel electrodes with silver nanoparticles for hydrogen production

"Silver nanoparticles were electrodeposited into the surface of a macroporous Ni electrode. The developed electrodes were characterized morphologically by confocal laser scanning microscopy and field emission scanning electron microscopy. The activity of the developed electrodes towards the hydrogen evolution reaction was assessed by pseudo-steady-state polarization curves and electrochemical impedance spectroscopy in alkaline solutions at different temperatures. The incorporation of the silver nanoparticles on the surface of the electrode improved the catalytic activity towards the hydrogen evolution reaction due to an improvement in the electrochemically active surface area rather than in the intrinsic catalytic activity.

Characterization of the kinetic arrest of martensitic transformation in Ni45Co5Mn36.8In13.2 melt-spun ribbons

"The kinetic arrest (KA) of martensitic transformation (MT) observed in Ni45Co5Mn36.8In13.2 melt-spun ribbons has been studied. These alloy ribbons show an ordered columnar-like grain microstructure with the longer grain axis growing perpendicular to ribbon plane and transform martensitically from a single austenitic (AST) parent phase with the L21-type crystal structure to a monoclinic incommensurate 6 M modulated martensite (MST). Results show that the volume fraction of austenite frozen into the martensitic matrix is proportional to the applied magnetic field. A fully arrest of the structural transition is found for a magnetic field of 7 T. The metastable character of the non-equilibrium field-cooled glassy state was characterized by introducing thermal and magnetic field fluctuations or measuring the relaxation of magnetization. The relaxation of magnetization from a field-cooled kinetically arrested state at 5 and 7 T follows the Kohlrausch–Williams–Watts (KWW) stretched exponential function with a ? exponent around 0.95 indicating the weak metastable nature of the system under the strong magnetic fields. The relationship between the occurrence of exchange bias and the frozen fraction of AST into the MST matrix was studied.

Functional responses of recently emerged seedlings of an endemic Mexican oak (Quercus eduardii) under climate change conditions

"Background: Climate change will increase temperature and reduce rainfall across temperate forests of Mexico. This can alter tree establishment dynamics within forest and in neighbouring man-made clearings. Hypotheses: Climate change will reduce emergence and survival of tree seedlings, and surviving plants will display functional responses matching with these changes. These effects should be more noticeable in clearings due to the lack of canopy cover. Studied species: Quercus eduardii (Fagaceae, section Lobatae) an oak species endemic to Mexico. Study site and years of study: Tree growing season 2015-2016 (rainy season) in a mature oak forest and a neighbouring clearing in Sierra de Álvarez, state of San Luis Potosí. Methods: In both habitats, we established control plots (under current climatic conditions) and climate change simulation plots (increased temperature and reduced rainfall). At the beginning of the growing season, we sowed acorns of Q. eduardii in these plots and monitored the emergence, survival and growth of seedlings. At the end of the growing season, we assessed functional responses on surviving seedlings. Results: Seedling emergence and survival were lower in climate change plots from both habitats. However, differences in survival between climate treatments were larger within the forest. Seedlings from climate change plots displayed functional responses indicating higher levels of thermal and water stress. Conclusions: This study indicates that climate change will constrain tree recruitment in Mexican oak forests. However, contrary to our expectations, it seems that these effects will be higher within forests than in man-made clearings.

Distribución de las principales especies de encinos (Quercus spp.) ante escenarios de cambio climático en la república mexicana

"La biodiversidad brinda servicios ecosistémicos indispensables para el bienestar humano y, por lo tanto, es fundamental conocer las especies que nos rodean y los sitios donde se localizan. Debido al acelerado cambio climático que actualmente se está manifestando, también es esencial estimar el efecto que esto tendrá sobre la biodiversidad. Un grupo de especies emblemático para México son los encinos (genero Quercus) debido a la gran variedad de servicios ecosistémicos que ofrecen a los mexicanos desde la época precolombina. Por tal motivo, los objetivos de esta investigación se englobaron en dos capítulos. En el primer capítulo se desarrolla una metodología para determinar áreas con elevada riqueza y endemismo de encinos. Esta metodología se basa en modelos de hábitat adecuado para determinar los rangos de distribución de los encinos, y mediante el solapamiento de estos rangos se estima la riqueza de especies a través de México. Esta metodología fue comparada con la metodología tradicional que se usa para tomar decisiones de conservación (conteo de ocurrencias reales en unidades espaciales discretas). Adicionalmente, se evaluó si los sitios con alta diversidad se encuentran dentro de áreas naturales protegidas del país. Los resultados indicaron que el 70% de la superficie de México cumple con los requerimientos climáticos para que se encuentre presente al menos una especie de encino. La riqueza de encinos se concentra en las principales regiones montañosas del país, pero la metodología propuesta predice un mayor número de especies en comparación con la metodología tradicional. Finalmente, al evaluar la ubicación de las áreas naturales protegidas, los resultados indicaron que la superficie destinada a proteger a los encinos es aún limitada. En el segundo capítulo se estima el efecto que tendrá el 2 cambio climático sobre la riqueza y composición de encinos a través del país. Para esto, se estimó la diversidad alfa y beta con la misma metodología utilizada en el primer capítulo, pero añadiendo las predicciones de dos escenarios de cambio climático (RCP2.6 y RCP8.5) para mediados del siglo XXI. Los resultados indicaron que la diversidad alfa (riqueza de encinos) disminuirá en ambos escenarios de cambio climático, siendo más acentuada en regiones con elevada riqueza. Los cambios en diversidad beta, por el contrario, serán más fuertes en regiones con menos número de especies. En ambos casos, los cambios serán más severos en el escenario RCP8.5. Estos resultados indican que, aunque las regiones con elevada riqueza son más propensas a sufrir extinciones de especies, la gran variedad de encinos que actualmente poseen les confiere mayor resiliencia a cambios en su composición. De esta investigación se concluye que los modelos de hábitat adecuado son una herramienta confiable para estimar la riqueza de especies sobre extensas áreas geográficas. Por ello, puede ser implementada para sustentar la toma de decisiones en materia de conservación. Con relación a los encinos, la situación actual es preocupante, debido a que no se cuenta con las suficientes áreas naturales protegidas que coadyuven a mantener sus poblaciones y las predicciones a futuro no son alentadoras para el género.""Biodiversity provides a number of ecosystem services for human well-being and, therefore, it is essential to know the species that surround us and the places where they are located. Because of the accelerated climate change that is currently occurring, it is also essential to estimate the effect that this will have on biodiversity. An emblematic group of species for Mexico are the oaks (genus Quercus) because of the wide variety of ecosystem services provide to Mexicans since pre-Columbian times. For this reason, the objectives of this study were included in two chapters. In the first chapter proposes novel a methodology to determine areas with high richness and endemism of oaks. This methodology uses habitat suitability models to determine the distribution ranges of oaks, and estimates species richness across Mexico by overlapping them. This methodology was compared with the traditional methodology used for making conservation decisions (counting real occurrences in discrete spatial units). Additionally, it was evaluated if sites with high diversity are within natural protected areas of this country. The results indicated that 70% of the surface of Mexico meets the climatic requirements for oaks. Richness of oaks is concentrated in the main mountain ranges of Mexico, but our methodology predicts greater numbers of species than the traditional methodology. Finally, when evaluating the location of protected natural areas, the results indicated that surface destined to protect oaks is still reduced. In the second chapter we estimate the effect that climate change will have on richness and composition of oaks across the country. For this, alpha and beta diversity were estimated with the same methodology used in the first chapter but, in this case, predictions of two climate change scenarios (RCP2.6 and RCP8.5) for the middle of the 21st century were added. The results indicated that alpha diversity (oak richness) 4 will decrease in both climate change scenarios, being more marked in highly-rich regions. Changes in beta diversity, on the other hand, will be stronger in regions with fewer species. In both cases, the changes will be more severe in the RCP8.5 scenario. These results indicate that, although regions with elevated richness are more prone to species extinctions, the great variety of oaks that they currently contain makes them more resilient to changes in their composition. This research allows concluding that habitat suitability models are a reliable tool to estimate species richness across extensive geographic areas. Therefore, it can be implemented in decision-making processes in conservation biology. Regard to the oaks, the current situation is worrisome, mainly because there are not enough natural protected areas to maintain their populations and the future for the diversity of this group of trees are not positive.

Análisis in vitro del péptido antiviral HRA2pl producido en tabaco, contra Ortopneumovirus y Rubulavirus humanos

"Las infecciones respiratorias agudas (IRA’s) representan un importante problema de salud ya que ocupan el segundo lugar a nivel mundial de morbimortalidad en niños menores de 5 años. Los principales agentes causales son los virus, entre los cuales se encuentran el Ortopneumovirus (hOPV), Metapneumovirus (hMPV), Respirovirus (hREV) y Rubulavirus humanos (hRUV) e Influenza Virus (IV), entre otros. Para el 2012 el costo estimado de las IRA’s por paciente hospitalizado en México es de aproximadamente $9, 000 dólares. En este estudio se agroinfiltraron plantas de Nicotiana benthamiana de 6 semanas de edad con Agrobacterium tumefaciens, para expresar el péptido HRA2pl que diseñado a partir del péptido HRA que es parte de la proteína de fusión F de hMNV. El péptido fue identificado por Dot blot y Western blot, fue purificado posteriormente por columna de afinidad de níquel y se analizó su efecto antiviral en líneas celulares de mamífero (HEp-2 y Vero) contra los virus hOPV y hRUV. En el ensayo de inhibición viral en placa se observó que para hOPV B la menor dosis infectiva media del cultivo celular (TCID50) fue de 362.6 con la dosis del péptido de 2.6x10-3 µg/mL y para hRUV-2 la menor TCID50 fue de 936.7 con la dosis del péptido de 1.8x10-3 µg/mL. Es importante resaltar que a pesar de estar diseñado para inhibir la fusión virus-célula de hMPV, es funcional también contra otros virus, como hOPV B y hRUV-2 debido a que tienen mecanismos de entrada son similares, por lo cual este péptido puede ser utilizado como tratamiento profiláctico en guarderías y hospitales para prevenir infecciones por estos patógenos.""Acute respiratory infections (ARI’s) represent a major health problem since they can rank second worldwide in terms of morbidity and mortality in children under 5 years old. The main causative agents are viruses; among the most frequent are human Orthopneumpvirus (hOPV), Metapneumovirus (hMPV), Respirovirus (hREV), Rubulavirus (hRUV) and Influenza Virus (IV), among others. For the 2012, the estimated cost of AIR’s per patient in Mexico was of approximately$ 9,000 USD. In this study, 6-week-old Nicotiana benthamiana plants were agroinfiltrated with Agrobacterium tumefaciens, to express the HRA2pl, which was designed from HRA, a fragment of the fusion protein F of hMPV. The peptide was detected by Dot blot and Western blot and was purified by nickel affinity column to analyze its antiviral effect on human cellular lines (HEp-2 and Vero) against hOPV and hRUV viruses. In plaque viral inhibition assay, it was shown that for hOPV B, the lowest median tissue culture infective dose (TCID50) was of 362.6 with the peptide dose of 2.6 x10-3 µg/mL and for hRUV-2 the TCID50 was 936.7 with the peptide dose of 1.8x10-3 µg/mL. It is important to highlight that although the peptide was designed to inhibit the hMPV virus-cell fusion, it is also functional for other viruses, such as hOPV B and hRUV-2 due to their similar infection mechanisms. Therefore this peptide can be used as a prophylactic treatment in day care centers and hospitals to prevent infections by these pathogens."Concejo Nacional de Ciencia y Tecnología (CONACYT

Physiological concentrations of zinc have dual effects on P2X myenteric receptors of guinea pig

"We, hereby, characterize the pharmacological effects of physiological concentrations of Zinc on native myenteric P2X receptors from guinea-pig small intestine and on P2X2 isoforms present in most myenteric neurons. This is the first study describing opposite effects of Zinc on these P2X receptors. It was not possible to determine whether both effects were concentration dependent, yet the inhibitory effect was mediated by competitive antagonism and was concentration dependent. The potentiating effect appears to be mediated by allosteric changes induced by Zinc on P2X myenteric channels, which is more frequently observed in myenteric neurons with low zinc concentrations. In P2X2-1 and P2X2-2 variants, the inhibitory effect is more common than in P2X myenteric channels. However, in the variants, the potentiatory effect is of equal magnitude as the inhibitory effect. Inhibitory and potentiatory effects are likely mediated by different binding sites that appear to be present on both P2X2 variants. In conclusion, in myenteric native P2X receptors, Zinc has quantitatively different pharmacological effects compared to those observed on homomeric channels: P2X2-1 and P2X2-2. Potentiatory and inhibitory Zinc effects upon these receptors are mediated by two different binding sites. All our data suggest that myenteric P2X receptors have a more complex pharmacology than those of the recombinant P2X2 receptors, which is likely related to other subunits known to be expressed in myenteric neurons. Because these dual effects occur at Zinc physiological concentrations, we suggest that they could be involved in physiological and pathological processes.

Diseño e implementación de arreglos de compuertas dinámicas programables en campo y su aplicación en redes booleanas

"A menudo, en el estudio de redes Booleanas es deseable poder llevar a cabo su realización electrónica. Con los dispositivos electrónicos comercialmente disponibles, este objetivo se puede lograr de dos maneras diferentes: mediante el uso de compuertas lógicas comerciales o por medio de un arreglo de compuertas programables en campo (FPGA). Sin embargo, cada una de estas metodologías presenta ciertos inconvenientes. Para superar estos inconvenientes, en esta tesis se diseña e implementa un arreglo de compuertas dinámicas programables en campo (FPDGA), el cual es un dispositivo reconfigurable conformado de compuertas lógicas dinámicas cuya funcionalidad e interconexión pueden ser configuradas por el usuario. La teoría matemática que sustenta el funcionamiento dinámico de las compuertas del FPDGA es desarrollada en este trabajo de tesis y consiste en un sistema no lineal. Con esta teoría, se logra que cada compuerta sea capaz de emular cinco operaciones lógicas. También se propone una forma de crear la estructura de ruteo programable que interconecta las compuertas unas con otras. La múltiple funcionalidad de las compuertas, en conjunto con la estructura de ruteo programable, representa una ventaja sobre los dispositivos reconfigurables existentes debido a que la ejecución de una función lógica compleja puede realizarse de manera directa. Aunado al diseño e implementación del FPDGA, en esta tesis es presentado un estudio analítico, numérico y experimental del fenómeno de sincronización entre un par de redes Booleanas autónomas acopladas bajo tres esquemas diferentes (unidireccional, bidireccional y forzamiento por una señal externa). Mediante un análisis basado en ecuaciones Booleanas con retardo, se calcula una señal de acoplamiento que permite a las redes alcanzar un estado de sincronización completa en cada uno de los esquemas utilizados. Estos resultados teóricos son corroborados por medio de simulaciones numéricas. En el caso del forzamiento por señal externa, los resultados también son verificados de manera experimental utilizando el FPDGA.""Often, in the study of Boolean networks it is desirable to be able to carry out their electronic realization. With commercially available electronic devices, this objective can be achieved in two different ways: through the use of commercial logic gates or through a FieldProgrammable Gate Array (FPGA). However, each of these methodologies has certain disadvantages. To overcome these disadvantages, in this thesis is designed and implemented a Field-Programmable Dynamical Gate Array (FPDGA), which is a reconfigurable device consisting of dynamical logic gates whose functionality and interconnection can be configured by the user. The mathematical theory that supports the dynamical functioning of the FPDGA’s gates is developed in this thesis work and consists of a non-linear system. With this theory, each gate is able to emulate five logical operations. A way to create the programmable routing structure that interconnects gates with each other is also proposed. The multiple functionality of gates, in conjunction with the programmable routing structure, represents an advantage over existing reconfigurable devices because the execution of a complex logic function can be performed directly. In addition to the design and implementation of FPDGA, this thesis presents an analytical, numerical and experimental study of the phenomenon of synchronization between a pair of autonomous Boolean networks coupled under three different schemes (unidirectional, bidirectional and forcing by an external signal). By means of an analysis based on Boolean delay equations, a coupling signal is calculated which allows the networks to achieve a complete synchronization state in each of the schemes used. These theoretical results are corroborated by means of numerical simulations. In the case of forcing by external signal, the results are also verified experimentally using the FPDGA.

Microalga como fuente de biomasa para la producción de biogás

"La biomasa microalgal es un sustrato idóneo para la producción de biocombustibles carbono neutrales, que representan una alternativa al uso de combustibles fósiles, entre ellos se encuentra el biogás. El biogás es una mezcla de 55-75% (CH4) y 45-25% (CO2) y se obtiene por medio de un proceso denominado digestión anaerobia. En el caso de la biomasa microalgal, es necesaria la aplicación de un pretratamiento a dicha biomasa para liberar los compuestos orgánicos susceptibles de convertirse en biocombustible, y así favorecer el proceso de digestión anaerobia. Cuando la digestión anaerobia se realiza en condiciones alcalinas el porcentaje de CH4 en el biogás será mayor que el obtenido a pH neutro, debido al equilibrio de fases a pH alcalino entre el CO2 producido por la DA y su disolución como bicarbonato en el líquido. Por tanto, resultaría conveniente aplicar un pretratamiento alcalino a la biomasa microalgal y posteriormente realizar la producción de metano en condiciones alcalinas, y evitar el uso de reactivos para neutralizar el pH de la biomasa pretratada. Además el acoplamiento de la digestión anaerobia con el cultivo de biomasa microalgal presenta la capacidad de secuestrar CO2 ya sea atmosférico, del propio biogás o del generado durante su combustión, así como de reciclar nutrientes (N y P). El presente trabajo tuvo como objetivo determinar la factibilidad de utilizar biomasa microalgal pretratada en condiciones alcalinas como sustrato para la producción de biogás. Se evaluaron diferentes pretratamientos termoalcalinos con distintos álcalis y condiciones de temperatura (NaOH y CaO); además se usó peróxido de hidrógeno alcalino (PHA). Los pretratamientos se realizaron sobre 2 lotes diferentes de biomasa microalgal de Scenedesmus obtusiusculus. Después de aplicar los diferentes pretratamientos termoalcalinos, se observó un aumento en la solubilización de materia orgánica de 10.8 a 19.5% con los diferentes pretratamientos. La digestión anaerobia en condiciones alcalinas requirió la aclimatación gradual de un lodo a pH 9, la cual se llevó a cabo en un reactor UASB de 1.25 L con un TRH 27.2 h. Las pruebas de potencial de metano se realizaron con un pH inicial de 9 en donde el rendimiento de producción más alto se obtuvo con PHA 1.5% a 50°C por 1.5 h para el Lote 1 y con NaOH 4 M a 120°C por 20 min tanto para el Lote 2 de biomasa microalgal (320.6 mL CH4/g SV y 227.1 mL CH4/g SV respectivamente). En cuanto a la velocidad de producción de metano no se encontraron diferencias significativas (p>0.5) entre la biomasa pretratada y sin pretratar en el Lote 1, para el Lote 2 la velocidad de producción más alta se obtuvo con NaOH 4M (28.8 mL/g SV·d). El porcentaje de metano presente en los ensayos de potencial de metano estuvo entre 78 a 100% a pH 9 y no fue necesaria la neutralización del hidrolizado ya que se contaba con lodo aclimatado a condiciones alcalinas.""Microalgal biomass is an ideal substrate for the production of neutral carbon biofuels, such as biogas, which represents an alternative to the use of fossil fuels. Biogas is a mixture of 55-75% (CH4) and 45-25% (CO2) and is obtained by anaerobic digestion. In order to digest the microalgal biomass it is necessary to apply a pretreatment to release the organic compounds susceptible to be transformed into biofuel, and thus favor the anaerobic digestion process. If the anaerobic digestion is carried out under alkaline conditions, the CH4 content in the biogas will be higher than that obtained at neutral pH, due to the phase equilibrium reached between the CO2 produce by the anaerobic digestion and its dissolution as bicarbonate in the liquid phase. Therefore, it would be convenient to apply an alkaline pretreatment to the microalgal biomass and subsequently to produce methane under alkaline conditions, and avoid the use of reagents to neutralize the pH of the pre-treated biomass. Besides the coupling of anaerobic digestion with microalgal biomass culture has the ability to sequester atmospheric CO2 and CO2 from the combustion process, as well as recycling nutrients (N and P). The aim of this work was to determine the feasibility of using pre-treated microalgal biomass as a substrate for the production of biogas under alkaline conditions. Therefore, different thermoalkaline pretreatments were evaluated with different conditions of temperature and alkalis NaOH and CaO; alkaline hydrogen peroxide (PHA) was also used for alkaline pretreatment. After applying the different thermoalkaline pretreatments to two lots of the microalgae Scenedesmus obtusiusculus (1 and 2), an increase in the solubilization of organic matter was observed from 10.8 to 19.5% with the different pretreatments. Anaerobic digestion under alkaline conditions required the gradual acclimatization of the anaerobic sludge at pH 9, which was carried out in a UASB reactor of 1.25 L with a HRT of 27.2 h. The methane potential tests were performed with an initial pH of 9 where the highest production yield was obtained with PHA 1.5% at 50 °C for 1.5 h for Lot 1 and with the pretreatment 4 M NaOH at 120 ° C for 20 min for Lot 2 (320.6 mL CH4 / g SV and 227.1 mL CH4 / g SV respectively). Regarding the rate of methane production, no significant differences were found (p> 0.5) between pretreated and untreated biomass in Lot 1, for Lot 2 the highest production rate was obtained with 4M NaOH (28.8 mL/g SV·d). The percentage of methane present in the methane potential tests varied from 78 to 100% at pH 9 and the neutralization of the hydrolysate was not necessary because an acclimated inoculum to alkaline pH was used.

On suitable observables for the chaotic Peroxidase-Oxidase autocatalytic reaction

"Neurodegenerative diseases such as Alzheimer’s and Parkinson present oxidative damage of neurocytes generally caused by reactive oxygen species (ROS). Heme peroxidases consume and produce ROS thus serving as suppresors and promoters of ROS-related pathology A core reaction network of production and consumption of hydrogen peroxide and superoxide is the Peroxidase-Oxidase (PO). PO reaction was among the first biochemical oscillators to be experimentally and numerically studied, with dynamical scenarios such as multiple steady states, complex oscillations and chaos. In particular, the oxyferrous peroxidase (compound III) and O2 have been used as observable variables in experiments to record the chaotic dynamics. Moreover, PO reaction has been embedded in nanoparticles in order to serve as a sensor for ROS. In this contribution we quantified, using observability coefficients, which chemical species is more suitable to observe and reconstruct the characteristic complex dynamics of the PO reaction.

Application of seaweed, natural biopolymers, and carbon-based materials as a wastewater treatment of water-soluble hydrocarbons

"Actualmente la liberación de hidrocarburos (HC) al medio acuático (> 6000 toneladas en 2016), es uno de los problemas emergentes de mayor impacto al ambiente. Una de las principales fuentes de emisión son los derrames de HC por actividades de la industria petroquímica. De acuerdo a estudios, los HC más solubles son los más tóxicos para organismos acuáticos. Las principales estrategias de respuesta contemplan el uso de tecnologías de adsorción. En años recientes, las investigaciones se han orientado a la búsqueda de materiales alternativos que permitan la remoción de contaminantes con capacidades de remoción similares a los adsorbentes comerciales. En este trabajo se evaluó la capacidad de biosorción de tres especies de macroalgas (pardas, verdes y rojas), a diferentes fuerzas iónicas. En los estudios de caracterización se detectó la presencia de los principales compuestos químicos presentes en la pared celular de los biomateriales. El incremento de la fuerza iónica a un valor hasta un valor de 0.5 M, no tiene un efecto detectable en la carga superficial de los biosorbentes, sin embargo la concentración de los grupos funcionales ácidos se mantuvo constante. La capacidad de adsorción de HC es mayor en biomasa del alga parda (M. pyrifera), donde el principal mecanismo se debe a la partición en la fase lipídica y compuestos de carbono no hidrolizable. La capacidad de adsorción de benceno por M. pyrifera disminuye a I > 0.45 M por la competencia de moléculas de agua por sitios activos en los biomateriales. Adicionalmente, mediante el uso de diseño de experimentos, se sintetizaron compositos a partir de la biomasa de M. pyrifera, quitosano (CS) y pectina. Los biomateriales fueron analizados en experimentos en lote y en continuo donde se demostró su factibilidad como biosorbentes para la remoción de los contaminantes de estudio. Por último, el óxido de grafeno (OG) es un alótropo de carbono con potencial aplicación en la remoción de contaminantes orgánicos en solución acuosa. Actualmente, su aplicación se ha visto limitada debido a su aglomeración y baja área específica (SBET). Ante esta problemática, la síntesis de sólidos laminares pilareados representa una alternativa al incrementar el área de adsorción y los sitios activos disponibles. El propósito principal de este estudio fue determinar el efecto de la co-precipitación de quitosano entre los espacios interlaminares del óxido de grafeno, y su afinidad por los principales hidrocarburos (HC) solubles en agua (benceno, tolueno y naftaleno). La proporción CS/OG = 0.1 empleando quitosano de bajo peso molecular, registró el mayor incremento del SBET (47 m2/g). Con el fin de elucidar los mecanismos de adsorción involucrados, se evaluó la afinidad por los HC de estudio a diferentes condiciones de pH, temperatura y presencia de materia orgánica"."Nowadays the recovery of low-molecular aromatic hydrocarbons (HC) released into natural bodies of water continues to be a challenging task. These contaminants cause severe consequences to the environment and the human health. The oil spill cleanup strategies are primarily designed to deal with HC heavy fractions accumulated in the water surface. Unfortunately, insufficient information is available regarding the treatment of dissolved fractions. Biosorption on macroalgae (Ma) biomass seems to be a potential alternative to overcome disadvantages associated with expensive costs and complexity of activated carbon production. Three representative samples of brown, green and red macroalgae seaweeds (Macrocystis pyrifera, Ulva expansa and Acanthophora spicifera, respectively) were evaluated to remove benzene and toluene from water, which is the most soluble hydrocarbons. To accomplish this objective, the influence of temperature and ionic strength on biosorption rate were also determined. Raw biomasses were characterized by different physical and chemical techniques to assess their potential as biosorbents and the mechanisms involved. Despite these advantageous properties of seaweed biomass, the physical characteristics (small particle size, low strength, and density) of such biomaterials are not viable for continuous process operation and make biomass challenging to apply. Therefore, the development of innovative low-cost techniques of immobilized biosorbents with particular attention to increasing their effectiveness in the biosorption process is mandatory. The objective of this research was to explore the performance of different biosorbent aggregates through different proportions of brown seaweed-chitosan-pectin on biosorption capacity of the three main soluble hydrocarbons (benzene, toluene, and naphthalene) in water. The biocomposite synthesis was optimized by application of the factorial design and response surface methodology. Moreover, a detailed chemical and physical characterization analysis, by textural properties, potentiometric titrations, elemental content, chemical stability, KBr-FT-IR, and TGA analysis, were performed to explain the adsorption mechanisms. Also, an optimized Ma-Pe-Ch biocomposite was used for BTEX and naphthalene removal in a fixed-bed column under different experimental conditions. Finally, alternative methods to functionalized graphene oxide with a water-dispersible material are needed to create GO composites for adsorption applications. By introducing molecules or other carbon-based components between GO sheets (pillared agents), an increase in the surface area of the material could be observed. The synthesis of different CS-GO composites achieved an optimized surface area of 47 m2/g (ratio CS/GO = 0.1). Various characterization techniques verified the presence of chitosan molecules between the GO sheets, creating grooves and high energetic adsorption sites. The hydrophobic effect and π-π interactions of the GO structures also with the chitosan (-OH) functional groups determined the favorable adsorption capacity in comparison with the un-modified GO".Durante la realización del trabajo el autor recibió una beca académica del Consejo Nacional de Ciencia y Tecnología (424187) y del Instituto Potosino de Investigación Científica y Tecnológica, A. C. La investigación desarrollada en esta tesis fue financiada a través del programa de Proyectos de Desarrollo Científico para Atender Problemas Nacionales (PDCPN−01−247032)