Adsorption of Nitrobenzene from Water onto High Silica Zeolites and Regeneration by Ozone

This work investigates the removal of nitrobenzene (NB), a model pollutant from water, by combining adsorption onto zeolites and regeneration with ozone. The adsorption equilibrium isotherms of NB onto zeolites enabled the best adsorbent to be selected and zeolites with a high Si/Al ratio were the most efficient. The adsorption capacity depended on the Si/Al ratio and on the pore size. In a sequential process coupling adsorption and oxidation by ozone, NB was completely removed from water and the initial adsorption capacity of the zeolite was totally restored. Although no catalytic effect was noticed, the adsorption produced locally high concentrations, thus enhancing the oxidation rate for NB

LPE Center News, November 2006

In this issue: • Waterborne Pathogens to be Discussed During the December Webcast • October Webcast and Power Point Slides Available • Coming Soon • Feed Management for CNMP Development Course Offered • The Debate About Animal Diet and Its Effects on E. coli 0157:H

Oxidation of nitrobenzene by ozone in the presence of faujasite zeolite in a continuous flow gas–liquid–solid reactor

This work investigates the oxidation of nitrobenzene (NB) by ozone in the presence of faujasite zeolite. Experiments were carried out in a gas–liquid–solid reactor were ozone transfer and NB oxidation took place at the same time. Three configurations of the reactor were compared: empty, filled with inert glass beads and filled with faujasite pellets. First, ozone transfer coefficient (kLa) and decomposition rate constant (kC) were determined for each configuration. In presence of solid, kLa was 2.0 to 2.6 times higher and kC was 5.0 to 6.4 times higher compared to the empty reactor. Then, the various configurations were evaluated in terms of NB removal and chemical oxygen demand (COD) decrease. The faujasite reactor showed higher removal of NB and decrease of COD compared to other configurations under the same conditions suggesting that the faujasite increases the oxidation rate of NB. Oxidation of NB in presence of faujasite also proved to be limited by the transfer of ozone from the gas to the liquid phase

The use of ozone and high silica zeolites to enhance refractory compounds removal

This work investigates the removal of organic pollutants from water through a three-phase process combining adsorption onto hydrophobic zeolites and in situ oxidation by ozone gas. Zeolites are aluminosilicates with various crystalline structures – and especially different pore sizes - which offer a great selectivity, profitable to organic pollutants separation in a complex matrix like natural water. They are highly resistant to chemical agents as acids, bases or oxidising agents such as ozone. Moreover, high silica zeolites have a high adsorption capacity for organics. Ozone is known to be a powerful oxidising agent able to react with various organic compounds. Its action – either direct or indirect - leads to the decomposition of organics into smaller molecules that are generally biodegradable. Previous studies have shown that organics adsorbed onto zeolites could be oxidised by ozonated water faster than in bulk water because of a micropore concentration effect (Fujita et al, 2004 and Sagehashi et al, 2005). In the gas phase, Monneyron et al (2003) showed that high silica zeolites could catalyse ozone decomposition into radical species and that adsorption properties were not significantly modified after exposition to ozone. Hence it is expected that zeolites saturated with organics could undergo regeneration by ozone without degradation of their structures or decrease of their adsorption capacities. The present work showed that high silica zeolites could efficiently adsorb nitrobenzene from water although their capacity stayed beyond that of activated carbon, except at low concentrations. The adsorption capacity depended on the zeolite structure and the Si/Al ratio. Adsorption isotherms could be well described by Langmuir or Freundlich models. As regards the three phase coupled process, the adsorbent could be efficiently regenerated during an ozonation step consisting in bubbling ozone through a suspension of saturated zeolite in a nitrobenzene solution at equilibrium. The initial adsorption capacity was quickly recovered and, continuing the treatment, the adsorption capacity of the zeolite was even increased. This may be due to the cleaning of zeolites pores by ozone (Pic et al, 2005). Yet traces of template molecules could probably remain from the zeolite synthesis process. Until now the catalytic effect of the zeolites has not been evidenced in the liquid phase. Therefore future work will focus on the conditions in which the oxidation kinetics can be enhanced in the presence of zeolites through a concentration effect, and to what extent

Enhanced bio-recalcitrant organics removal by combined adsorption and ozonation

Removal of bio-recalcitrant and toxic compounds from wastewaters has been a major objective of industrial manufacturers for a few years. Due to the potential risk toward public health,regulations are becoming increasingly strict and classical treatments like biological treatments are not efficient. Other techniques such as incineration, oxidation or adsorption provide higher levels of removal but with a high energy and capital cost. A coupled process involving adsorption and oxidation is studied. Four adsorbents are tested and compared according to two objectives,their adsorption capacity and their capability to decompose ozone into powerful hydroxyl radicals. Two model compounds were chosen: 2,4-dichlorophenol and nitrobenzene.Experimental results allow comparing coupled process with results obtained during ozonation alone. Zeolite (Faujasite Y) gave disappointing results in term of both adsorption kinetics and ozone decomposition. On the contrary, activated carbons showed fast adsorptions and important capabilites to decompose ozone into radicals, almost in nitrobenzene experiments. S-23 activated carbon proved to be the most interesting adsorbent for better mechanical and chemical stabilities over time. Sequential adsorption/ozonation experiments were conducted,showing a strong loss of adsorption efficiency after the first operation, but the positive point is that the adsorption capacity remains almost constant during further cycles

Fluid phase equilibria of the reacting mixture in the dimethyl carbonate synthesis from supercritical CO2

In order to investigate the dimethyl carbonate synthesis from methanol and supercritical CO2, the thermodynamic behaviour of the reacting mixture, i.e. the quaternary methanol/CO2/DMC/water mixture, has to be known. The SRK equation of state with MHV2 mixing rules has been chosen to predict fluid phase equilibria in the reactor. The first part of this work is dedicated to the determination of binary interaction parameters, needed in the use of this model. These parameters are deduced from the fitting of experimental data concerning binary or ternary sub-systems existing in the quaternary mixture. Literature data was used for most of the binary sub-systems, but for the DMC/CO2 and DMC/water mixtures, specific experiments were carried out. The agreement between experimental and predicted fluid phase equilibria was found to be satisfactory. With a view to studying of the operating conditions for the reaction, the thermodynamic model was used to predict fluid phase equilibria in the reactor, by considering several hypothetical feed ratios and conversions. This work shows that CO2 has to be used in large excess in order to be sure of running the reaction in a homogeneous fluid medium

Coupled selective adsorption and ozonation for non biodegradable COD removal

This paper investigates a new water treatment process based on the combined use of the pollutant adsorption onto a mineral surface, and the ozonation of the adsorbed species. Dioxane has been chosen as a model compound as it is refractory towards ozone alone, and two adsorbents (a high silica zeolite FAU and a mesoporous material M) are tested. Three sets of experiments are shown: pollutant adsorption alone, pollutant ozonation alone and the coupled adsorption/ozonation process. The first results show that FAU is not a well suited adsorbent, as dioxane adsorption itself is weak and, moreover, the coupled process does not induce any benefit. On the other hand, mesoporous material M gives better results, since dioxane removal has been achieved up to 50%. The difference between the two materials is attributed to their catalytic effect: whereas FAU does not react with ozone, M probably decomposes the oxidant, generating free radical species and thus acting as an advanced oxidation process

La observación de diferencias de género en balonmano

Superar una mirada superficial en relación al género en balonmano, mediante la identificación de diferencias entre chicas y chicos en competiciones de alto nivel es objetivo del presente trabajo. Sobre qué variables o criterios (lanzamientos, efectividad, espacio y señalizaciones arbitrales) y categorías observacionales descansan estas diferencias resulta esencial para poder identificar comportamientos estratégicos. Se recurrió a una metodología observacional para registrar los eventos del juego. Fueron seleccionados dos partidos de balonmano femenino y dos partidos masculinos, pertenecientes a las fases finales de los juegos olímpicos de Londres 2012. El diseño observacional fue nomotético, puntual y multidimensional. Se diseñó una herramienta ‘ad hoc’, puesta en práctica por dos evaluadores. Una vez fueron registrados los datos mediante el software Lince, fueron analizados mediante la técnica de reducción de datos Theme. Los resultados evidenciaron la existencia T-patterns en función del género.Overcoming a superficial view regarding the gender in handball, through the identification of differences between women and men in high level competitions is the objective of this work. Knowing on which observational variables or criteria (throwing, effectiveness, zone and referee signs) and categories these differences rely is essential for identifying strategic behaviors. An observational methodology was used to record the events of the game. Two women's and two men's handball matches were selected, belonging to the final phases of the London 2012 Olympic Games. The observational design was nomothetic, punctual and multidimensional. An ‘ad hoc’ tool was designed, and it was implemented by two evaluators. Once the data were recorded using the Lince software, they were analyzed through the data reduction technique Theme. The results evidenced the existence of T-patterns based on gender.peerReviewe

Role of Lewis acid sites of ZSM-5 zeolite on gaseous ozone abatement

In this work, chemical interactions between ozone and zeolite surface active sites are studied in order to propose a process for gaseous ozone removal. Synthetic ZSM-5 zeolites with three different Si/Al2 ratios and similar specific surface areas and microporous volumes were used in this study. Zeolite samples were characterised using Fourier Transform InfraRed spectroscopy (FTIR) and pyridine sorption IR studies in order to determine acidic site concentrations and strength. Ozone removal experiments were conducted in a quartz fixed-bed flow reactor, at 20°C and 101 kPa. Experiments using Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) were conducted in order to identify adsorbed ozone and/or adsorbed oxygen species on zeolite surface. Pyridine IR measurements evidence two kinds of Lewis acid sites induced by extra-framework aluminium species and electronic aluminium defaults inside zeolite structure. Results obtained here evidence the important role of acidic surface sites of ZSM-5 zeolite on gaseous ozone removal. The total amount of removed ozone is found to be directly proportional to the total content of Lewis acid sites. DRIFTS experiments exhibit two bands around 800 and 1400 cm-1 that could correspond to adsorbed oxygen species linked to zeolite surface. DRIFTS experiments also exhibit a band around 1100 cm-1 that correspond to adsorbed ozone on the zeolite surface. Gaseous ozone removal using ZSM-5 zeolite could be largely attributed to ozone decomposition on Lewis acid sites and also to ozone adsorption on the surface of the zeolites

La calidad temporal de registros en balonmano

Este trabajo es un estudio exploratorio para incrementar el control de la calidad del dato, mediante el empleo de coeficientes de correlación temporal. La consolidación de la metodología observacional (Anguera, 2017) ha venido precedida por mejoras de distinta índole. Se partió de una herramienta de registro observacional aplicada al balonmano y compuesta por criterios y categorías. El diseño del estudio se correspondió con el cuadrante III, a) nomotético, puntual, multidimensional. Dos observadores registraron partidos de balonmano (N=4) con ayuda del software Lince. Se emplearon los paquetes estadísticos SPSS v. 24 y JASP v. 0820 para así asociar los tiempos de cada registro inter observador y calcular los coeficientes de correlación entre otros análisis. La aplicación práctica del trabajo tendría en el análisis del comportamiento motor un campo de aplicación pero no el único. Abordar la sincronización de los observadores al registrar es un procedimiento susceptible de avanzar en fiabilidad y precisión.This work is an exploratory study to increase data quality control, by using temporal correlation coefficients. The consolidation of the observational methodology (Anguera, 2017) has been preceded by improvements of a different nature. It was based on an observational registration tool applied to handball and made up of criteria and categories. The study design corresponded to quadrant III, as a) nomothetic, isolated, and multidimensional. Two observers recorded handball matches (N=4) with the help of Lince software. Statistical packages, SPSS v. 24 and JASP v. 0820, were used to associate the times of each inter-observer register and calculate the correlation coefficients among other analysis. The practical application of the work would have in the analysis of motor behavior an application but that is not the only one. Addressing the synchronization of observers when registering is a procedure open to improvement both in reliability and accuracy.Ministerio de Economía y Competitividad, con financiación de FEDER. Proyectos: “La actividad física y el deporte como potenciadores del estilo de vida saludable: evaluación del comportamiento deportivo desde metodologías no intrusivas” (DEP2015-66069-P) y “Avances metodológicos y tecnológicos en el estudio observacional del comportamiento deportivo” (PSI2015-71947-REDP)peerReviewe