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In this work, the chemical structural characterization of the erionite-type zeolite from Agua Prieta, Sonora, M&eacute, xico, was performed on both pristine and Na, Ca, and Mg exchanged samples in order to identify the various modifications due to cation exchange. The samples investigated were those that showed the best behaviour of CO2 and CH4 adsorption at zero coverage levels and the higher values of surface area reported in our previous studies. According to the crystal-chemical formula (Na3.44K1.96Mg0.63Ca0.62)[Al8.21Si27.79O71.85]&middot, 29.63H2O, the pristine sample has been classified as erionite-Na. Morphological FE-SEM investigation performed on both pristine (ERIN) and Na-exchanged samples (ERINa3) showed a similar range of fiber diameters (27&ndash, 37 nm). The chemical analyses of the ion-exchanged samples evidenced the upload of Ca and Mg following ion exchange with Na. Rietveld analysis results allowed the identification of the chemical structural modification caused by the ion exchange process, occurring mainly at the Ca1 site.

The objective of this study was to prepare composite materials based on mesoporous silica/carbon, functionalized with acid groups, and also to analyze its application in the adsorption of dyes. These materials were prepared in a simplified unconventional route. The carbon phase was generated by direct carbonization of organic surface-active templates, which are used in the synthesis of meso-ordered silicas. The resulting composite materials were characterized in terms of their structure, texture, chemical composition, and surface chemical reactivity. Data obtained demonstrate uniform and ordered porous structures of approximately 70–200 Å, with a developed surface area of approximately 400–500 m2 g−1 and a large total pore volume of approximately 1.0–1.5 cm3 g−1. The potential of synthesized composite materials functionalized by oxygenated groups as adsorbents of cationic dyes was analyzed, the values of the maximum adsorption capacity between 317 mg g−1 and 245 mg g−1 were obtained. The adsorbing properties of silica/carbon composite materials obtained in an unconventional method using an organic template as the only carbon source were compared with the properties of silica/carbon composite materials manufactured by the conventional method using external precursors of the carbon phase. It has been proved that composite materials synthesized using an unconventional procedure, despite the fact that they have a lower carbon phase content, exhibit adsorption properties that are comparable or superior to materials elaborated in the traditional way, removing up to 85–90% of methylene blue from water contaminated with dye.

It presents the results of the microstructural and morphological characterization of a natural Zeolite from the province of Chiriqui, Panama. By X-ray diffraction and Rietveld refinement, the presence of Zeolite Natural Analcima is determined, but with other related minerals, from the point of view of their geological formation, such as: Albite, Diopside and Sanidine mainly. The use of the Fourier Transform Infrared Spectroscopy (FTIR) technique confirms the presence of the Analcima. Combining thermal treatments to the Zeolite and studying the variation of its FTIR spectra, it is inferred that Analcima (and its other constituents) is stable up to 600 °C, since its absorption spectrum does not change significantly, while at higher temperatures absorption bands related crystalline water bonds, progressively decrease up to 1000 °C, where they disappear. The evaluation of the Scanning Electron Microscopy Analcime reveals a mixed morphology, consisting of structures in the form of columns, sheets and polygonal particles, as well as cavities of approximately 5 micrometers in diameter. A particular detail is that with the heat treatment of the Zeolite up to 1000 ° C, the morphology does not change significantly, which suggests the microstructural stability of the Zeolite.

The chitinase enzyme was identified in isolated bacteria of maize rhizosphere as well as its potential for the biological control of fungi associated at seeds of the same plant. The production of c...

Antecedentes: La seta silvestre de maguey (Pleurotus opuntiae) es un alimento importante de las zonas semi-áridas del centro de México, apreciado por campesinos e indígenas desde tiempos antiguos, de sabor deseable y aprovechado en épocas de lluvias; sin embargo, hay pocos estudios acerca de su cultivo. Objetivos: Comparar la producción y calidad nutritiva de basidiomas de P. opuntiae y P. ostreatus cultivados en paja de trigo, así como evaluar la combinación de diferentes residuos agrícolas combinados con penca de maguey para el cultivo de P. opuntiae, en condiciones controladas. Métodos: Pleurotus opuntiae y P. ostreatus se cultivaron en pencas de maguey y residuos agrícolas pasteurizados a 80 °C/2 h. Se cuantificó la producción total, eficiencia biológica y tasa de producción. Se realizó un estudio químico proximal de los basidiomas obtenidos en los diferentes sustratos. El diseño estadístico fue por bloques al azar, además se realizó un análisis de componentes principales para determinar la correlación entre los rendimientos. Resultados y conclusiones: Los mejores parámetros productivos se obtuvieron en paja de trigo con la cepa de P. ostreatus, pero P. opuntiae presentó un mayor contenido de proteína cruda y cenizas en la combinación de dos residuos agrícolas con penca de maguey.

Emissions of carbon dioxide (CO2) and nitrogen dioxide (NO2) in recent years has been increased considerably. One way to reduce the concentration of these greenhouse gases in the atmosphere is adsorptive capture. This paper describes the main results of adsorption of N2, NO2, and CO2 on epistilbite, both natural and on samples that were chemically treated at various concentrations of HCl. Data on the adsorption of CO2 and NO2 were evaluated by the Freundlich and Langmuir equations. Additionally, the thermodynamic parameters of adsorption were calculated, including the degree of interaction of the zeolite samples with gases by gradually changing the isosteric heat capacities of adsorption. The acid treatment improves the adsorption capacity of epistilbite with respect to NO2 and CO2, due the replacement of large extra-framework cation by small H+ ions. The improvement in the distribution of pore sizes in epistilbite samples was calculated by the method of Barrett-Joyner-Halenda. The sample H1 that was prepared in a moderately concentrated acid showed the best behavior in the CO2 adsorption processes, while the natural EPIN material preferably adsorbs NO2.

By selective acid leaching, silica nanotubes were prepared from the natural mineral chrysotile asbestos. These one-dimensional tube actually represent a convolution of twodimensional layers, and the subsequent stacking the tubes into a hexagonal assembly generates three-dimensional body. Made materials are acid-and heat-resistant and can be used as feedstock in the manufacture of filters, or as matrices for the synthesis of nanomaterials.

This work is devoted to the study of copper ion positions in zeolite matrices. Copper cations were exchanged in mordenite and zeolite X from aqueous solutions of different copper salts varying their concentrations. Electronic state of copper in ion-exchanged samples exchanged and dried at different temperatures was evaluated by XPS spectroscopy. Depending on conditions of exchange treatment copper was found to be distributed between two different accessible sites in zeolites. These copper ions are stabilized as isolated species with well-defined oxygen coordination polyhedra.

Three different zeolites (erionite, mordenite and natural clinoptilolite) were used to study influence of zeolite topology on the state of copper during ion-exchange and following reduction in hydrogen flow. This comparative study clearly demonstrates the influence of used zeolite matrices on the process of implantation of copper nanospecies. Starting from the ion-exchange, the alterations in the state of Cu2+ ions start to be evident due to variations of the intensity of charge transfer band. Copper ions start to reduce at specific temperatures depending on the type of zeolite matrix. Copper plasma resonance band change its shape and position for different zeolites. In the case of Cu-CLI samples this band change both the shape and position for different temperature of reduction. These observations permit to suggest that the mechanism of copper ion reduction and agglomeration to form copper nanoparticles noticeably depend on the type of zeolite matrix. This mechanism is more complex for the Cu CLI than for the Cu-MOR and Cu-ERI systems. Copper nanoparticles formed at low temperatures in the case of Cu-CLI samples undergo changes while temperature of reduction grow.

En este trabajo investigación, se estudia la capacidad de adsorción de tolueno sobre una serie de siete combinaciones de óxidos de aluminio, cerio y zirconio, preparados por el método solgel mediante cromatografía de gases en un intervalo de temperatura de 200°C a 250°C. El área superfi cial, es alta para las cuatro muestras que contienen alúmina, entre 196 y 272 m2/g, mientras que las tres restantes poseen áreas superficiales menores a 40 m2/g. La adsorción de tolueno se observóen las siete muestras, sin embargo, las cuatro que contienen alúmina presentan isotermas cóncavas lo que indica adsorción favorable, mientras que en las de ceriazirconia, la forma de las isotermas es convexa indicando adsorción no favorable, lo anterior se confi rma al observar menor cantidad de tolueno adsorbido comparada con las muestras anteriores. La temperatura que favorece la adsorción en la mayoría de las muestras es la de 200 °C.

Carbon dioxide (CO2) is considered one of the most important greenhouse gases in the study of climate change. CO2 adsorption was studied using the gas chromatography technique, while the Freundlich and Langmuir adsorption models were employed for processing isotherm data in the temperature range of 473–573 K. The isosteric heat of adsorption was calculated from the Clausius–Clapeyron equation. Moreover, the thermodynamic properties ΔG, ΔU, and ΔS were evaluated from the adsorption isotherms of Langmuir using the Van’t Hoff Equation. The four soil samples were recollected from San Juan Amecac, Puebla, Mexico, and their morphologies were investigated through X-ray diffraction (XRD) and N2 adsorption at 77 K. The SJA4 soil has a crystalline Kaolinite phase, which is one of its non-metallic raw materials, and N2 isotherms allowed for the determination of pore size distributions and specific surface areas of soil samples. The Barrett–Joyner–Halenda (BJH) distribution of pore diameters was bimodal with peaks at 1.04 and 3.7 nm, respectively. CO2 adsorption showed that the SJA1 soil afforded a higher amount of adsorbed CO2 in the temperature range from 453 to 573 K followed by SJA4 and finally SJA2, classifying this process as exothermic physisorption.

Comunicaciones del IV Congreso Internacional sobre análisis fílmico celebrado en la Universitat Jaume I de Castellón 4,5 y 6 de mayo de 2011

"En el presente trabajo se estudiaron las propiedades fisicoquímicas de la zeolita, clinoptilolita, originaria de Tehuacán, Puebla, México, para ser usada como aditivo en el substrato para el cultivo del hongo Pleurotus ostreatus. Estos estudios consistieron en métodos de difracción de rayos X, adsorción de alta resolución de N2 a 77.5 K y composición química. La clinoptilolita sesometió a molturado, triturado y tratamiento térmico y químico, con las siguientes soluciones: CO(NH2)2 0.123 M (N), KCl 0.230 M (K), Ca(H2PO4)2 0.079 M (P) y NH4NO3 + Ca(H2PO4)2 + KCl 0.040 M (NPK) por 2 días. La difracción de rayos X indicó que las muestras de clinoptilolita tratada no sufrieron variación en su estructura cristalina al ser tratadas con las soluciones. Se observó una secuencia perfectamente establecida en cuanto a la superficie específica (AsB) alutilizar el método desarrollado por Brunauer, Emmett y Teller (BET), AsB: NPK > P > K > CLINA > N. De la determinación de la composición química de la zeolita se comprobó que los nutrientes quedaron depositados en la estructura de la clinoptilolita."

El suelo rizosférico se encuentra interactuando con compuestos de bajo peso molecular como los ácidos carboxílicos, entre otras sustancias, cuya dinámica de sorción a la superficie de las partículas minerales se desconoce. Se determinó por el método cromatográfico, la adsorción de agua y ácidos carboxílicos volátiles de origen vegetal y bacteriano (metanoico, etanoico, propanoico y butanoico) en un suelo agrícola de San Juan Atenco, Puebla, México. El suelo de estudio, se caracterizó en sus propiedades físicas, químicas, biológicas y de superficie. Se determinó la porosidad por el método de adsorción de N2 a su temperatura de ebullición (76 K). Los valores de la superficie específica fueron determinados utilizando el método de Brunauer- Emmett-Teller (BET), el volumen de poro fue obtenido aplicando el método de Gursvitch y la distribución de tamaño de poros fue estudiada por la aproximación de Barrett-Joyner-Halenda (BJH). La adsorción de los adsorbatos ha sido determinada en el intervalo de temperaturas de 423-523 K, usando cromatografía de gases con detector de conductividad térmica y usando helio como gas portador. Los principios de las ecuaciones de Freundlich y Langmuir fueron aplicadas a todos los casos. Los resultados demuestran que la adsorción de agua y ácidos carboxílicos volátiles, derivados del metabolismo biológico en el suelo, está en función de la estructura diferencial de las moléculas, repercutiendo en el grado de interacción al sistema poroso del suelo.