Simultaneous adsorption of quinoline and dibenzothiophene over Ni-based mesoporous materials at different Si/Al ratio

In this study, two mesoporous materials such as MCM-41 and Ni/MCM-41 were modified with Al at different Si/Al ratios. The mesoporous materials were proved as sorbents of heterocyclic nitrogen and sulfur compounds employing quinoline (Q) and dibenzothiophene (DBT), respectively, as model molecules of that precursor pollutants at the same concentrations of ppmw of nitrogen and sulfur (N:S = 1 ratio). The sample with the highest Si/Al ratio showed the highest specific surface, and at low Si/Al decreased the specific surface. With X-ray diffraction (XRD) the Ni containing in MCM-41, there is a clear trend and the highly hexagonal ordered sample is the one without Al and once the Al is added, the hexagonal ordering is highly modified. Employing NH3-TPD and NMR revealed that the samples with Si/Al = 5 and 16 have higher Lewis acid sites than another ratio of Si/Al. The modification successfully added small amounts of Ni that did not collapse the pore structure but increased the density of surface (acidic) groups that in turn favored the uptake of the sulfur compound through π-complexation adsorption mechanism. It is also possible to recognize that the samples with a Si/Al ratio of 5 and 16 revealed the presence of the highest surface density of weak acid sites for both sorbents. Adsorption experiments were carried out in a batch adsorption system at 313 K and atmospheric pressure using a model mixture from diesel containing: DBT, Q, and 40 ml of dodecane. The sulfur adsorption was substantially improved when Ni was incorporated to MCM-41; for example, at 250 ppmw of N uptake of DBT was almost twice than MCM-41 alone. This result would indicate that Ni/MCM-41 could remove both molecules but mainly the nitrogen molecule at high concentrations. The Langmuir and Freundlich adsorption isotherms were used for all materials considering Q in the presence of DBT depending on the Si/Al ratio. This behavior did not happen for the DBT whose behavior was modelled by an isotherm of the Freundlich type for Ni/MCM-41 and adsorbed in acid sites and multilayer. Lastly, experimental results indicated that MCM-41 with Si/Al = ∞ has the highest (Q/DBT) selectivity of 13,390 at 50 ppmw N compared to another Si/Al ratio, for example, at 250 ppmw N

Zn supported on Zr modified mesoporous SBA-15 as sorbents of pollutant precursors contained in fossil fuels: Si/Zr ratio effect

The adsption processes have become an additional alternative to hydrotreatment processes of oilderived middle distillates. The crucial point is the type of adsorbent employed. SBA-15 mesoporous materials were used to adsorb quinoline (Q) and dibenzothiophene (DBT) as N- and S-containing model species, espectively, contained in a model mixture mimicking middle distillates. Q and DBT in dodecane solutions (50-250 ppm and 500 ppm, respectively) were used to that end. In order to improve the adsorption properties, SBA-15 was modified, incorporating zirconium at Si/Zr weight ratios of 5, 16, 60, and 150. At those ratios, Q was adsorbed preferably, whereas DBT was removed only below 10%. To increase the amount of S dsorbed, Zn was incorporated at 2 wt. %. At 250 ppm (sol. concentration) of N, the amount adsorbed of Q and DBT on the material without Zn (Si/Zr=5) was 1.51 and 0.02 mmolgads -1, respectively. The results were notably different when Zn was incorporated in adsorbents. In these case, amounts of adsorbed Q and DBT were 2.2 and 1.3 mmolgads -1, respectively, showing that metal sites are essential to adsorb DBT

Selective adsorption of nitrogen compounds using silica-based mesoporous materials as a pretreatment for deep hydrodesulfurization

The adsorption of quinoline (Q) and dibenzothiophene (DBT)—model compounds for nitrogen and sulfur in diesel fuels—over mesoporous SBA-15, SBA-16, and MCM-41 was studied. The Langmuir model was suitable for describing the adsorption of nitrogen-containing compounds from a simulated diesel fuel. A pseudo-second order kinetic model better fitted the Q adsorption data than a first-order rate model when describing the adsorption rates on all materials. Comparison of the adsorption of Q and DBT confirmed that the nitrogen compound was selectively removed, and MCM-41 was found to have better adsorption characteristics than SBA-15 and SBA-16. DBT was not adsorbed in any experiment. The adsorbents were characterized using N2-physisorption, powder X-ray diffraction, and high-resolution transmission electron microscopy to describe the morphologies of the adsorbents. The characterization results revealed that the specific area and the structure of the adsorbent are key parameters required to explain the adsorption process

Simulación de una planta para la hidratación de etileno empleando el simulador ProMax 3.2

En el presente trabajo se realizó la simulación de las diversas etapas que conforman una planta de producción de etanol, de la cual se utilizó etileno como materia prima, empleando el simulador ProMax 3.2 (Bryan Research & Engineering, Inc.), en dicho proceso se considera una producción de 210 Kg / h. Para el desarrollo del proyecto se realizó el balance de materia y energía correspondiente para cada operación unitaria que en conjunto constituyen el proceso químico; además se determinaron las condiciones óptimas de operación de las corrientes pertinentes. Adicionalmente se determinó eficiencia de operación del reactor, también los rendimientos de los intercambiadores de calor y bombas, por último, se determinaron las dimensiones óptimas de las piezas de los componentes en cada operación unitaria; para concluir se determinó el valor promedio para construcción de la planta.In this work, we performed the simulation of the various stages that make up an ethanol production plant, from which ethylene was used as raw material, using the ProMax 3.2 simulator (Bryan Research & Engineering, Inc.), in this process it’s consider a 210 kg / h for production. For the development of the project, the material and energy balance for each unit operation that together constitute the chemical process was made; in addition, the optimum operating conditions of the relevant currents were determined. In addition, reactor operating efficiency, yields of heat exchangers and pumps were also determined; finally, the optimum dimensions of the component parts were determined in each unit operation; to conclude, the average value for the construction of the plant was determined

Degradación fotocatalítica del colorante negro reactivo 5 (RB-5) empleando zeolitas naturales modificadas térmicamente

En el presente trabajo se analizaron muestras minerales de zeolitas, en forma de polvos y sometidas a tratamiento térmico de 250, 350 y 500 °C, respectivamente, las cuales son de interés particular debido a sus propiedades catalíticas. El proceso de tratamiento consiste en molienda mecánica de las muestras sólidas, proceso que se realizó durante 3 horas, posteriormente la calcinación de la muestra se efectuó en 4 horas. La caracterización estructural de los materiales se llevó a cabo por DRX, mientras que la morfología se determinó con SEM y se calculó el ancho de banda prohibida de los materiales empleando RD-UV-Vis y la transformada de Kubelka-Munk. La reacción de fotodegradación de un compuesto textil llamado, colorante reactivo 5 (RB-5) se llevó a cabo en un reactor intermitente con una lámpara de luz blanca de λ = 570 nm, a presión y temperatura ambiente; la cinética de degradación se monitoreo en la banda de absorción (λ = 595 y 310 nm) con espectroscopia UV-Vis.In the this work mineral zeolitic samples was analyzed, in powder form and heat treated 250, 350 and 500 ° C, respectively, which are of particular interest due to their catalytic properties. The treatment process consists of mechanical grinding of solid samples, process conducted for 3 hours, subsequently calcining the sample for 4 hours. The structural characterization of the materials was carried out by XRD, while morphology was determined by SEM and width bandgap materials by using RD-UV-Vis and Kubelka-Munk transform. Photo-degradation reaction of textile compound called, reactive black 5 dye (RB-5) was carried out in a batch reactor with a white light lamp of λ = 570 nm, ambient temperature and pressure; the kinetics of degradation reaction was monitored by checking the variation on absorption band (λ = 595 and 310 nm) with UV -Vis spectroscopy

Effect of Ni on MCM-41 in the Adsorption of Nitrogen and Sulfur Compounds to Obtain Ultra-Low-Sulfur Diesel

Adsorption of heterocyclic sulfur and nitrogen compounds like dibenzothiophene (DBT) and quinoline (Q), respectively, was carried out using mesostructured adsorbent MCM-41 and Ni/MCM-41 in calcined (C) and reduced (R) form. These materials were proved in a batch adsorption system using a model fuel diesel: a mixture of dodecane, DBT and Q with the same concentrations of ppmw of sulfur and nitrogen at 313 K and atmospheric pressure. When MCM-41 was impregnated with Ni, an important modification of the adsorption properties was observed, for example, the uptake of DBT was increased and this adsorption was twice in Ni/MCM-41 in reduce form than in the calcined form. On the other hand, for the nitrogen adsorption of Q diminished by 62 and 58%, considering Ni/MCM-41 in reduce form and in calcined form as adsorbent, respectively. This is a significant achievement regarding the desulfurization and denitrogenation, especially for commercial diesel without pretreatment. Moreover, the kinetic results were adjusted with second order considering Q as nitrogen and DBT as sulfur molecule. Data fitting for Q was achieved better by the Langmuir model for all materials than the Freundlich model, meanwhile the experimental adsorption data of DBT was fitted to the Freundlich model for Ni/MCM-41 calcinated and reduced form

Análisis estructural y luminiscente de redes metal orgánicas de tenoltrifluoroacetona tridopadas con tierras raras

Los iones lantánidos unidos con ligandos orgánicos como el Tenoltrifluoroacetona (TTA) ofrecen un gran potencial en el área óptica, sin embrago, la investigación en síntesis y propiedades del lantánido, las estructuras luminiscentes de metal orgánico (LMOF) se limitan a un solo ion de tierras raras lo cual limita sus propiedades y rendimiento a la emisión monocromática. En este trabajo se reportan los resultados de DRX, MEB y EDS, y luminiscencia de las síntesis exitosas de Tenoltrifluoroacetona dopado con tierras raras de Europio, Terbio y Disprosio a la misma red metal orgánica a temperatura ambiente haciendo una reacción en un recipiente con los nitratos de los lantánidos y precursores de Tenoltrifluoroacetona. También se realizó la comparación entre las síntesis dopadas individualmente con los centros de tierras raras como centros activadores luminiscentes al ligando orgánico TTA y la síntesis dopada con los tres centros metálicos. A partir de los estudios de DRX, se encontró que las estructuras cristalinas son similares para cada una de las síntesis.Lanthanide ions with organic ligands such as Thenoyltrifluoroacetone (TTA) offer great potential in the optical area; however, research on synthesis and properties of lanthanides, luminescent structures of organic metals (LMOF) is limited to a single rare earth ion which limits its properties and performance to monochromatic emission. In this work the results of XRD, SEM and EDS, and the luminescence of the successful synthesis of Thenoyltrifluoroacetone doped with rare earths of europium, terbium and dysprosium are reported to the same network of organic metals at room temperature making a reaction in a container with lanthanide nitrates and Thenoyltrifluoroacetone precursors. The comparison between the synthesis doped individually with the rare earth centers as luminescent activating centers for the organic ligand TTA and the synthesis doped with the three metal centers was also presented

Compromising between European and US allergen immunotherapy schools: Discussions from GUIMIT, the Mexican immunotherapy guidelines

Background: Allergen immunotherapy (AIT) has a longstanding history and still remains the only disease-changing treatment for allergic rhinitis and asthma. Over the years 2 different schools have developed their strategies: the United States (US) and the European. Allergen extracts available in these regions are adapted to local practice. In other parts of the world, extracts from both regions and local ones are commercialized, as in Mexico. Here, local experts developed a national AIT guideline (GUIMIT 2019) searching for compromises between both schools. Methods: Using ADAPTE methodology for transculturizing guidelines and AGREE-II for evaluating guideline quality, GUIMIT selected 3 high-quality Main Reference Guidelines (MRGs): the European Academy of Allergy, Asthma and Immunology (EAACI) guideines, the S2k guideline of various German-speaking medical societies (2014), and the US Practice Parameters on Allergen Immunotherapy 2011. We formulated clinical questions and based responses on the fused evidence available in the MRGs, combined with local possibilities, patient's preference, and costs. We came across several issues on which the MRGs disagreed. These are presented here along with arguments of GUIMIT members to resolve them. GUIMIT (for a complete English version, see Supplementary data) concluded the following: Results: Related to the diagnosis of IgE-mediated respiratory allergy, apart from skin prick testing complementary tests (challenges, in vitro testing and molecular such as species-specific allergens) might be useful in selected cases to inform AIT composition. AIT is indicated in allergic rhinitis and suggested in allergic asthma (once controlled) and IgE-mediated atopic dermatitis. Concerning the correct subcutaneous AIT dose for compounding vials according to the US school: dosing tables and formula are given; up to 4 non-related allergens can be mixed, refraining from mixing high with low protease extracts. When using European extracts: the manufacturer's indications should be followed; in multi-allergic patients 2 simultaneous injections can be given (100% consensus); mixing is discouraged. In Mexico only allergoid tablets are available; based on doses used in all sublingual immunotherapy (SLIT) publications referenced in MRGs, GUIMIT suggests a probable effective dose related to subcutaneous immunotherapy (SCIT) might be: 50–200% of the monthly SCIT dose given daily, maximum mixing 4 allergens. Also, a table with practical suggestions on non-evidence-existing issues, developed with a simplified Delphi method, is added. Finally, dissemination and implementation of guidelines is briefly discussed, explaining how we used online tools for this in Mexico. Conclusions: Countries where European and American AIT extracts are available should adjust AIT according to which school is followed

EDUCACIÓN AMBIENTAL Y SOCIEDAD. SABERES LOCALES PARA EL DESARROLLO Y LA SUSTENTABILIDAD

Este texto contribuye al análisis científico de varias áreas del conocimiento como la filosofía social, la patología, la educación para el cuidado del medio ambiente y la sustentabilidad que inciden en diversas unidades de aprendizaje de la Licenciatura en Educación para la Salud y de la Maestría en Sociología de la SaludLas comunidades indígenas de la sierra norte de Oaxaca México, habitan un territorio extenso de biodiversidad. Sin que sea una área protegida y sustentable, la propia naturaleza de la región ofrece a sus visitantes la riqueza de la vegetación caracterizada por sus especies endémicas que componen un paisaje de suma belleza