305,289 research outputs found
[Entrevista com Carla Simone Rodeghero e Clarissa Sommer Alves]
No full textO Programa de Educação Patrimonial (PEP) é fruto de uma exitosa parceria entre o Departamento de História da Universidade Federal do Rio Grande do Sul (UFRGS) e o Arquivo Público do Estado do Rio Grande do Sul (Apers). A iniciativa começou em 2008, a partir de um projeto de extensão que passou a incorporar diversas ações vinculadas à educação patrimonial. Além de promover a difusão arquivística através de oficinas para estudantes da educação básica, o PEP também capacita graduandos de história e oferece cursos de formação para professores sobre os usos possíveis do acervo da instituição arquivística e dos seus espaços para produção do conhecimento. Calcada na conscientização sobre a importância do patrimônio cultural arquivístico e no debate de temas sensíveis para a sociedade brasileira, a iniciativa já levou ao Apers quase 16 mil estudantes. Nessa entrevista, conversamos com as condutoras do programa, a professora doutora Carla Simone Rodeghero, titular da UFRGS, e a historiadora Clarissa Sommer Alves, mestre em História e analista em assuntos culturais do Apers
Structural evidences of competitive adsorption of VOCs and humic monomers from water on high-silica zeolites: a combined X-ray powder diffraction and chromatographic study
No full textVolatile organic compounds (VOCs) such as toluene, chlorobenzene, 1,2-dichloroethane and methyl-tert-buthyl-ether are commonly found in natural and drinking water. When these compounds are dissolved in groundwater are considered dangerous for the health of human and ecosystems already at low concentration [1]. For this reason, the removal of this organics from natural water is of considerable interest. Actually, a reliable alternative to obtain this goal is based on the adsorption technique by means of high-silica zeolites. The efficiency of the hydrophobic zeolites adsorption, from aqueous solution, has been highlighted in recent studies and its success is due to both selectivity and flexibility of the framework of these materials [2-4]. Moreover, the process does not induce the formation of dangerous secondary molecules for the environment. On the basis of as reported, in this work the interaction and mobility of some VOCs pollutants have been studied. Those VOCs have characterized by different chemical properties and molecular dimensions, and they are adsorbed in organophilic synthetic zeolites (ZSM-5 and Y with MFI and FAU topology, respectively) which differ in topology, channel systems and free window apertures. Furthermore, it has been checked the efficiently of these materials paying attention on the pollutants adsorption in presence of common competitors, such as humic monomers (e.g. caffeic acid and para-hydroxybenzaldheyde), by monitoring the structural features. Indeed, the presence of organic matter could influence the process of adsorption of pollutants in the waters competing for the available adsorption sites, either by limiting access to the micro-pores. The selected organophilic and hydrophobic zeolites were commercial as-synthesized with high SiO2/Al2O3 (up to 200). Kinetics and adsorption isotherm batch data were obtained via Headspace Solid Phase Microextraction-GC. After pollutants adsorption the structural characterization was obtain by using X-ray powders diffraction data collected on a Bruker D8 Advance diffractometer equipped with SOL-X detector. To determinate the total weight loss of zeolites loaded with fuel-based compounds thermal analyses (TG and DTA) were performed in air up to 900°C at 10°C/min. This combined study allowed us to: a) measure the sorption capacity of hydrophobic zeolite materials weighed against organic pollutants dissolved in water; b) characterise the structure after contaminants adsorption; c) localise the organic species in the zeolite channel systems; d) highlight the role of humic monomers in the pollutants removal; e) probe the interaction between the adsorbate and the zeolite framework.
[1] P.V.O. Trindade, L.G. Sobral, A.C.L. Rizzo, S.G.F. Leite, Chemosphere, 2005, 58, 515–522.
[2] A. Martucci, I. Braschi, C. Bisio, E. Sarti, E. Rodeghero, R. Bagatin, L. Pasti, RSC Advances, 2015, 5(106), 86997.
[3] A. Martucci, E. Rodeghero, L. Pasti , V. Bosi, G. Cruciani , Microporous and Mesoporous Materials, 2015, 215, 175.
[4] E. Rodeghero, A. Martucci, G. Cruciani, R. Bagatin, E. Sarti, V. Bosi, L. Pasti, Catalysis Today, 2016, In Press (doi:10.1016/j.cattod.2015.11.031)
Desorption of chlorobenzene confined in Y zeolite: a combined in situ synchrotron X-ray powder diffraction and chromatographic study
No full textVolatile organic compounds (VOCs) such as chlorobenzene are common pollutants present in groundwater. Because of their human and ecosystems toxicity and their tendency to persist in water the removal of these contaminants it is in the public interest. Recently, the state of the art highlighted that hydrophobic zeolites are environmentally friendly materials, efficient as contaminants adsorbents and perfectly regenerable without changing their initial adsorption capacity (Martucci et al., 2015; Leardini et al., 2015; Martucci et al., 2015; Martucci et al., 2014; Pasti et al., 2012, Rodeghero et al., in press; Pasti et al., submitted). Structural and kinetic dynamic data are required to full understanding the behaviour of zeolites during the fuel-based compounds desorption process. Actually no in situ structural investigation of the VOCs kinetics desorption has been performed on Y zeolite. The challenge of this work is understanding the structural modifications undergoing on this hydrophobic material (HSZ-390HUA, SiO2/Al2O3 = 200, Tosoh Corporation) loaded with chlorobenzene (Cl-B) upon thermal treatment. To obtain this goal the study was carried out with two approaches. Firstly adsorption isotherm from distilled water was performed on zeolites in batches at RT and the concentration of contaminants in aqueous solution was obtained by gas chromatography and mass spectrometry. Then the in situ heating allowed us to simulate the regeneration process, which is usually subjected exhausted zeolites after adsorption of hydrocarbons. The desorption process was continuously monitored at the ID22 beamline (ESRF-Grenoble) as a function of temperature (heating rate 20°C/min) from room temperature up to 600°C. The results obtained with Rietveld method indicate that after thermal treatment zeolite does not show any significant crystallinity loss and when all the organic have been ejected (about 300°C), non-equilibrium distortions in the framework are relaxed and channel apertures become more circular. Achieving the reactivation of these materials and its reuse as pollutants adsorbent would expand their capabilities in environmental applications. Additionally, understanding this process can help in optimizing and the design the water remediation technologies (e.g. Permeable Reactive Barriers) and using zeolites as “molecular sieves” to remove fuels-based pollutants from water.
Leardini, L., Quartieri, S., Vezzalini, G., Arletti, R. (2015): Thermal behaviour of siliceous faujasite: Further structural interpretation of negative thermal expansion. Microporous and Mesoporous Materials, 202, 226–233.
Martucci, A., Braschi, I., Marchese, L., Quartieri, S. (2014): Min. Mag., 2014, 1115–1140.
Martucci, A., Braschi, I., Bisio, C., Sarti, E., Rodeghero, E., Bagatin, R. and Pasti, L. (2015): Influence of water on the retention of methyl tertiary-butyl ether by high silica ZSM-5 and Y zeolites: a multidisciplinary study on the adsorption from liquid and gas phase. RSC Adv., 106, 86997-87006. Martucci, A., Rodeghero, E., Pasti, L., Bosi, V., Cruciani, G. (2015): Adsorption of 1,2-dichloroethane on ZSM-5 and desorption dynamics by in situ synchrotron powder X-ray diffraction. Microporous and Mesoporous Materials, 215, 175-182.
Pasti, L., Rodeghero, E., Sarti, E., Bosi, V., Cavazzini, A., Bagatin R., and Martucci, A.: Competitive Adsorption of VOCs from binary aqueous mixtures on zeolite ZSM-5. RSC Adv., Submitted.
Pasti, L., Martucci, A., Nassi, M., Cavazzini, A., Alberti, A., Bagatin, R. (2012): The role of water in DCE adsorption from aqueous solutions onto hydrophobic zeolites. Micropor. Mesopor. Mat., 160, 182–193.
Rodeghero, E., Martucci, A., Cruciani, G., Bagatin, R., Sarti, E., Bosi, V., Pasti, L. (2015): Kinetics and dynamic behaviour of toluene desorption from ZSM-5 using in situ high-temperature synchrotron powder X-ray diffraction and chromatographic techniques. Catalysis Today, In Press
CHROMATOGRAPHIC AND STRUCTURAL STUDY OF THE ADSORPTION/DESORPTION PROCESS OF ZSM-5 LOADED WITH VOLATILE ORGANIC COMPOUNDS
No full textThe water contamination has increased significantly in recent years due to a very fast development of
industries as well as of intense agricultural practices. As a matter of fact that the development of
progress has given rise to a general improvement of the standard of living, but it had increased the
environment pollution through the wide release of contaminants of emerging concern (CECs) [1]. In
particular, the presence of these chemicals at ultra-trace levels causes the development of sublethal
toxic effects in aquatic organisms and in human health [2]. Nowadays, the traditional wastewater
treatments (i.e., vaporization, dilution, decomposition, and reactions to sunlight action) designed to
degrade or remove these pollutants or reduce the levels of their concentrations are not completely
effective. To support the traditional methods, new technologies which employ different types of
materials have been developed. Among these technologies, adsorption method based on the use of
adsorbent materials have been shown to be an effective and eco-friendly alternative. In particular,
hydrophobic zeolites have proven to be very promising materials, which have been employed as
adsorbents for the removal of contaminants from water bodies [3,4]. Indeed, zeolites represent an
important adsorbents for the recovery of groundwater polluted by organic complexes and can be easily
regenerated by thermal processes without changing their initial adsorption features [3,5].
On the basis of the above statements, the combination of chromatographic, diffractometric and
thermogravimetric techniques has been employed to investigate the adsorptive-desorptive properties
of hydrophobic synthetic zeolite as well as the temperature dependence of the desorption processes.
Specifically, time-resolved high-temperature synchrotron X-ray powder diffraction was used as a tool
to understand the behaviour of hydrophobic ZSM-5 zeolite (SiO2/Al2O3 ~ 280) during the desorption
of 1,2 dichloroethane, toluene, and methyl tert-butyl ether (adsorbed both as single component as well
as binary mixtures). The structural modifications of ZSM-5 zeolite are monitored through thermal
treatment from room temperature to 600 °C. The results achieved by means of Rietveld refinements of
the investigated compounds highlight the “out-of-equilibrium effects” that govern the
adsorption/desorption dynamic conditions in ZSM-5 powders.
[1] C. Perego, R. Bagatin, M. Tagliabue, R. Vignola (2013). Zeolites and related mesoporous materials for multi-talented environmental
solutions. Microporous and Mesoporous Materials, 37 – 49.
[2] M. Raghav, S. Eden, K. Mitchell, B. Witt (2013). Contaminants of Emerging Concern in Water. The Arroyo, 1 – 12.
[3] E. Rodeghero, A. Martucci, G. Cruciani, R. Bagatin, E. Sarti, V. Bosi, L. Pasti (2016). Kinetics and dynamic behaviour of toluene
desorption from ZSM-5 using in situ high-temperature synchrotron powder X-ray diffraction and chromatographic techniques. Catalysis
Today, 118–125.
[4] L. Pasti, E. Rodeghero, E. Sarti, V. Bosi, A. Cavazzini, R. Bagatin and A. Martucci (2016). Competitive adsorption of VOCs from binary
aqueous mixtures on zeolite ZSM-5. RSC Advance, 54544–54552.
[5] A. Martucci, E. Rodeghero, L. Pasti, V. Bosi, G. Cruciani (2015). Adsorption of 1,2-dichloroethane on ZSM-5 and desorption dynamics
by in situ synchrotron powder X-ray diffraction. Microporous and Mesoporous Materials, 175-182
Desorption of chlorobenzene confined in Y zeolite: a combined in situ synchrotron X-ray powder diffraction and chromatographic study
No full textVolatile organic compounds (VOCs) such as chlorobenzene are common pollutants present in groundwater. Because of their human and ecosystems toxicity and their tendency to persist in water the removal of these contaminants it is in the public interest. Recently, the state of the art highlighted that hydrophobic zeolites are environmentally friendly materials, efficient as contaminants adsorbents and perfectly regenerable without changing their initial adsorption capacity (Martucci et al., 2015; Leardini et al., 2015; Martucci et al., 2015; Martucci et al., 2014; Pasti et al., 2012, Rodeghero et al., in press; Pasti et al., submitted). Structural and kinetic dynamic data are required to full understanding the behaviour of zeolites during the fuel-based compounds desorption process. Actually no in situ structural investigation of the VOCs kinetics desorption has been performed on Y zeolite. The challenge of this work is understanding the structural modifications undergoing on this hydrophobic material (HSZ-390HUA, SiO2/Al2O3 = 200, Tosoh Corporation) loaded with chlorobenzene (Cl-B) upon thermal treatment. To obtain this goal the study was carried out with two approaches. Firstly adsorption isotherm from distilled water was performed on zeolites in batches at RT and the concentration of contaminants in aqueous solution was obtained by gas chromatography and mass spectrometry. Then the in situ heating allowed us to simulate the regeneration process, which is usually subjected exhausted zeolites after adsorption of hydrocarbons. The desorption process was continuously monitored at the ID22 beamline (ESRF-Grenoble) as a function of temperature (heating rate 20°C/min) from room temperature up to 600°C. The results obtained with Rietveld method indicate that after thermal treatment zeolite does not show any significant crystallinity loss and when all the organic have been ejected (about 300°C), non-equilibrium distortions in the framework are relaxed and channel apertures become more circular. Achieving the reactivation of these materials and its reuse as pollutants adsorbent would expand their capabilities in environmental applications. Additionally, understanding this process can help in optimizing and the design the water remediation technologies (e.g. Permeable Reactive Barriers) and using zeolites as “molecular sieves” to remove fuels-based pollutants from water.
Leardini, L., Quartieri, S., Vezzalini, G., Arletti, R. (2015): Thermal behaviour of siliceous faujasite: Further structural interpretation of negative thermal expansion. Microporous and Mesoporous Materials, 202, 226–233.
Martucci, A., Braschi, I., Marchese, L., Quartieri, S. (2014): Min. Mag., 2014, 1115–1140.
Martucci, A., Braschi, I., Bisio, C., Sarti, E., Rodeghero, E., Bagatin, R. and Pasti, L. (2015): Influence of water on the retention of methyl tertiary-butyl ether by high silica ZSM-5 and Y zeolites: a multidisciplinary study on the adsorption from liquid and gas phase. RSC Adv., 106, 86997-87006. Martucci, A., Rodeghero, E., Pasti, L., Bosi, V., Cruciani, G. (2015): Adsorption of 1,2-dichloroethane on ZSM-5 and desorption dynamics by in situ synchrotron powder X-ray diffraction. Microporous and Mesoporous Materials, 215, 175-182.
Pasti, L., Rodeghero, E., Sarti, E., Bosi, V., Cavazzini, A., Bagatin R., and Martucci, A.: Competitive Adsorption of VOCs from binary aqueous mixtures on zeolite ZSM-5. RSC Adv., Submitted.
Pasti, L., Martucci, A., Nassi, M., Cavazzini, A., Alberti, A., Bagatin, R. (2012): The role of water in DCE adsorption from aqueous solutions onto hydrophobic zeolites. Micropor. Mesopor. Mat., 160, 182–193.
Rodeghero, E., Martucci, A., Cruciani, G., Bagatin, R., Sarti, E., Bosi, V., Pasti, L. (2015): Kinetics and dynamic behaviour of toluene desorption from ZSM-5 using in situ high-temperature synchrotron powder X-ray diffraction and chromatographic techniques. Catalysis Today, In Press
Toluene and n-hexane competitive adsorption on high-silica ZSM-5 zeolite
No full textFuel-based compounds, such as toluene and n-hexane, are common pollutants present in water and wastewater. Due
to their tendency to persist in air, water and soil and to bioaccumulate through the food chain, they are included among
the most hazardous compounds for human health and environment. Acquatic ecosystems are especially vulnerable
because of the frequent use of water bodies as recipients of potentially toxic liquids and solids from domestic,
agricultural and industrial wastes. Hence, the removal of fuel-based compounds, through adsorption onto inorganic
sorbents is of considerable interest. Due to their selectivity towards organic contaminant and fast adsorption kinetics, it
has been recently highlighted that High Silica Zeolites are hydrophobic sorbent materials suitable for adsorption
processes (Martucci et al., 2015; Pasti et al., 2016). The aim of this work is to determine the ZSM-5 zeolite degree of
selectivity and its structural changes when a competitive adsorption of toluene and n-hexane occurs. A sample of ZSM-
5 zeolite (MFI topology, SiO2/Al2O3 ratio=280), was provided by Tosoh Corporation and loaded with a binary mixture
of toluene and n-hexane. Kinetics and adsorption isotherm data were obtained via Headspace Solid Phase
Microextraction-GC. Powders patterns were collected before and after adsorption on a Bruker D8 Advance
diffractometer equipped with SOL-X detector. Thermal (TG and DTA) analysis were performed in air up to 900°C at
10°C/min. This multidisciplinary approach allowed us to: 1) measure the sorption capacity of zeolite materials weighed
against organic pollutants dissolved in water; 2) characterise the sorbent structure after pollutant adsorption; 3) localise
the organic species in the zeolite channel systems; 4) probe the interaction between the adsorbate and zeolite framework.
Rietveld refinements provide information about the relative position of molecules inside the structure after toluene, nhexane
and their mixture adsorption. Data reveal that 1) n-hexane and toluene are preferentially adsorbed whether as
single components than as binary mixture; 2) zeolite selectivity is higher towards the n-hexane than toluene. Differences
Fourier maps analysis shows that n-hexane, water, and toluene have been adsorbed at about 8.95%, 2.2%, and 1.59%,
respectively, in good agreement with both adsorption data and thermal analysis. As a matter of fact, ZSM-5 zeolite
preferably adsorbs n-hexane, even in presence of a competitor, such as toluene.
Martucci, A., Braschi, I., Bisio, C., Sarti, E., Rodeghero, E., Bagatin, R., Pasti, L. (2015): Influence of water on the retention of
methyl tertiary-butyl ether by high silica ZSM-5 and Y zeolites: a multidisciplinary study on the adsorption from liquid and gas
phase. RSC Adv., 5, 86997-87006.
Pasti, L., Rodeghero, E., Sarti, E., Bosi, V., Cavazzini, A., Bagatin, R., Martucci, A. (2016): Competitive adsorption of VOCs from
binary aqueous mixtures on zeolite ZSM-5. RSC Adv., 6, 54544-54552
High temperature characterization of Y-zeolite loaded with chlorobenzene
No full textDue to their widespread use in many industrial sectors, low solubility in water and their bioaccumulation tendency,
Volatile Organic Compounds (VOCs) are hazardous organic chemicals commonly present in water. Among this class of
pollutants, chlorobenzene (CB) is included as benzene (i.e., BTEX species) halogenated compound. Therefore, due to
its toxic effects on both human health and environmental systems, the removal of CB from water is a primary issue.
Recently, it has been highlighted that organophylic and hydrophobic zeolites are efficient as sorbent materials and
completely regenerable without showing remarkable changes in adsorption capacity and structural properties.
Nowadays, these zeolites features, combined with their high thermal stability, are exploited in regeneration processes
through thermal treatment in order to reuse regenerated zeolites in new adsorption processes (Rodeghero et al., 2016).
Therefore, the aim of the project is to investigate the desorption process of chlorobenzene (purchased by Sigma Aldrich
with a purity of 99.8%) Y (HSZ-390HUA code; 200 SiO2/Al2O3 ratio) system to: 1) determine the desorption
temperature of extraframework content; 2) characterize the structural modifications induced by high temperature
treatment and 3) highlight the temperature effects on the interactions between organic molecules and framework oxygen
atoms. With this purpose, Y-CB sample was prepared and characterized by chromatographic (via Headspace Solid
Phase Microextraction-GC) and thermal (TG and DTA) analysis. Desorption process was constantly monitored, through
synchrotron X-ray powder diffraction, at the high resolution Beamline ID22 (ESRF, Grenoble) from room temperature
to 590°C with a heating rate of 8°C/min. Rietveld refinements showed that chlorobenzene molecules are desorbed at
about 210°C. These results are in good agreement with thermal analysis, which suggest that all the extraframework
(H2O and CB molecules) content is completely released between 190 and 210°C. Hence, the detected desorption
temperature reveals an acceleration of desorption kinetics compared to that reported on a patent previously published
(Vignola et al., 2008). Moreover, structural refinements highlighted that both only slight memory effects in terms of
structural deformations are registered in 12MR channel geometry after regeneration process and the reactivated zeolite
regain the unit-cell parameters of the bare material almost perfectly. Furthermore, any significant crystallinity loss is
observed. Based on these results, the High Silica Y zeolite is potentially reusable in a new adsorption/desorption cycle.
Rodeghero, E., Martucci, A., Cruciani, G., Bagatin, R., Sarti, E., Bosi, V., Pasti, L. (2016): Kinetics and dynamic behaviour of
toluene desorption from ZSM-5 using in situ high-temperature Synchrotron X-ray diffraction and chromatographic techniques.
Catalysis Today, 277, 118-125.
Vignola, R. (2008): WO 2009/000429 A1, Eni S.p.A
Chlorobenzene adsorption/desorption confined into y zeolite: a combined in situ high-temperature synchrotron powder X-ray diffraction and chromatographic study
No full textThe occurrence and fate of fuel-based pollutants in the aquatic environment has been recognised as one of the emerging issues in environmental chemistry. Their harmful effects on the environment make very interesting their removal from natural water. Recently, it has been reported that hydrophobic zeolites are environmentally compatible materials, which have been employed as adsorbents for the removal of contaminants from water bodies [1-4]. Besides, these materials can be easily thermally regenerated without changing their initial features and reused in pollutants adsorption processes [5-8]. For this reasons the present work aims to investigate the structural modifications related to the regeneration of a hydrophobic Y zeolite (HSZ-390HUA, SiO2/Al2O3 = 200, Tosoh Corporation) after chlorobenzene (Cl-B) adsorption which is a common VOCs present in water. Indeed, structural and kinetic dynamic data are required to full understanding the above process but actually no in situ structural investigation of the kinetics desorption has been performed on zeolite FAU topology. Initially kinetics and adsorption isotherm batch data were obtained via Headspace Solid Phase Microextraction-GC. Then the desorption process was continuously monitored at the ID22 beamline (ESRF-Grenoble) as a function of temperature (heating rate 20°C/min) from room temperature up to 600°C. Rietveld refinements allowed as to determinate the variations of the framework geometry due to the heat-induced desorption of organic molecules. Moreover, the results indicate that after thermal treatment zeolite does not show any significant crystallinity loss. The sample regeneration is effective when it is thermally treated at about 300°C. Above this temperature, when all the organic have been ejected, non-equilibrium distortions in the framework are relaxed and channel apertures become more circular. Additionally, understanding this process can help in optimizing and the design the water remediation technologies (e.g. Permeable Reactive Barriers) and using zeolites as “molecular sieves” to remove fuels-based pollutants from water.
[1] A. Martucci, I. Braschi, L. Marchese, S. Quartieri, Min. Mag., 2014, 1115–1140.
[2] L. Pasti, A. Martucci, M. Nassi, A. Cavazzini, A. Alberti, R. Bagatin, Micropor. Mesopor. Mat., 2012,
182–193.
[3] L. Pasti, E. Sarti, A. Cavazzini, N. Marchetti, F. Dondi, A. Martucci, J. Sep. Sci., 2013, 1604–1611;
[4] A. Martucci, I. Braschi, C. Bisio, E. Sarti, E. Rodeghero, R. Bagatin and L. Pasti, RSC Adv., 2015,
86997-87006.
[5] A. Martucci, E. Rodeghero, L. Pasti , V. Bosi, G. Cruciani , Microporous and Mesoporous Materials,
2015, 175-182.
[6] E. Rodeghero, A. Martucci, G. Cruciani, R. Bagatin, E. Sarti, V. Bosi, L. Pasti, Catalysis Today, in
press.
[7] L. Pasti, E. Rodeghero, E. Sarti, V. Bosi, A. Cavazzini, R. Bagatin and A. Martucci, RCS Adv.,
submitted.
[8] L. Leardini, S. Quartieri, G. Vezzalini, R. Arletti, Microporous and Mesoporous Materials, 2015, 226–
233
Chlorobenzene adsorption/desorption confined into y zeolite: a combined in situ high-temperature synchrotron powder X-ray diffraction and chromatographic study
No full textThe occurrence and fate of fuel-based pollutants in the aquatic environment has been recognised as one of the emerging issues in environmental chemistry. Their harmful effects on the environment make very interesting their removal from natural water. Recently, it has been reported that hydrophobic zeolites are environmentally compatible materials, which have been employed as adsorbents for the removal of contaminants from water bodies [1-4]. Besides, these materials can be easily thermally regenerated without changing their initial features and reused in pollutants adsorption processes [5-8]. For this reasons the present work aims to investigate the structural modifications related to the regeneration of a hydrophobic Y zeolite (HSZ-390HUA, SiO2/Al2O3 = 200, Tosoh Corporation) after chlorobenzene (Cl-B) adsorption which is a common VOCs present in water. Indeed, structural and kinetic dynamic data are required to full understanding the above process but actually no in situ structural investigation of the kinetics desorption has been performed on zeolite FAU topology. Initially kinetics and adsorption isotherm batch data were obtained via Headspace Solid Phase Microextraction-GC. Then the desorption process was continuously monitored at the ID22 beamline (ESRF-Grenoble) as a function of temperature (heating rate 20°C/min) from room temperature up to 600°C. Rietveld refinements allowed as to determinate the variations of the framework geometry due to the heat-induced desorption of organic molecules. Moreover, the results indicate that after thermal treatment zeolite does not show any significant crystallinity loss. The sample regeneration is effective when it is thermally treated at about 300°C. Above this temperature, when all the organic have been ejected, non-equilibrium distortions in the framework are relaxed and channel apertures become more circular. Additionally, understanding this process can help in optimizing and the design the water remediation technologies (e.g. Permeable Reactive Barriers) and using zeolites as “molecular sieves” to remove fuels-based pollutants from water.
[1] A. Martucci, I. Braschi, L. Marchese, S. Quartieri, Min. Mag., 2014, 1115–1140.
[2] L. Pasti, A. Martucci, M. Nassi, A. Cavazzini, A. Alberti, R. Bagatin, Micropor. Mesopor. Mat., 2012,
182–193.
[3] L. Pasti, E. Sarti, A. Cavazzini, N. Marchetti, F. Dondi, A. Martucci, J. Sep. Sci., 2013, 1604–1611;
[4] A. Martucci, I. Braschi, C. Bisio, E. Sarti, E. Rodeghero, R. Bagatin and L. Pasti, RSC Adv., 2015,
86997-87006.
[5] A. Martucci, E. Rodeghero, L. Pasti , V. Bosi, G. Cruciani , Microporous and Mesoporous Materials,
2015, 175-182.
[6] E. Rodeghero, A. Martucci, G. Cruciani, R. Bagatin, E. Sarti, V. Bosi, L. Pasti, Catalysis Today, in
press.
[7] L. Pasti, E. Rodeghero, E. Sarti, V. Bosi, A. Cavazzini, R. Bagatin and A. Martucci, RCS Adv.,
submitted.
[8] L. Leardini, S. Quartieri, G. Vezzalini, R. Arletti, Microporous and Mesoporous Materials, 2015, 226–
233
COMPETITIVE ADSORPTION OF VOCs FROM AQUEOUS SOLUTIONS ON HYDROPHOBIC ZEOLITES
No full textVolatile Organic Compounds (VOCs) are water pollutants of concern, due to their widespread occurrence in natural and drinking waters and to their adverse effects on human health [1]. The adsorption efficiency of hydrophobic zeolites toward unary mixtures of VOCs in water has already been proved [2-3]. Different contaminants have been investigated (i. e. methyl tert-butyl ether, toluene, 1,2-dichloroethane and chlorobenzene) which were selected to represent different VOC classes: oxygenated, aromatics, chlorinated aliphatics and chlorinated aromatics, respectively. Since usually multiple pollutants coexist in the environment, the quantification of competitive interactions is important to predict the adsorption capability of materials for complex aqueous mixtures. This study aims to evaluate the adsorption of binary mixtures of VOCs in aqueous solutions on a commercial hydrophobic zeolite ZSM-5. To investigate the kinetics and the thermodynamics of the adsorption process, equilibrium measurements were carried under different operative conditions and structural analysis was performed on the loaded zeolite. The results showed that the adsorption capabilities of ZSM-5 for all the compounds were reduced in the presence of a second component in the mixture, in comparison with the single-component data, indicating a competitive adsorption. The binary system was described by a competitive dual site Langmuir adsorption isotherm, according to the results obtained by structural analysis. It has been found that each site inside the zeolite framework cannot be occupied simultaneously by more than one component, because of the short intermolecular distances among the adsorption sites.
[1] Volatile Organic Compounds in the Nation’s Ground Water and Drinking-Water Supply Wells; Circular 1292, 2006, U.S. Geological Survey
[2] A. Martucci, E. Rodeghero, L. Pasti , V. Bosi, G. Cruciani, Microporous and Mesoporous Materials, 215, 175-182.(2015)
[3] E. Rodeghero, A. Martucci, G. Cruciani, R. Bagatin, E. Sarti, V. Bosi, L. Pasti, Catalysis Today (2015), in pres
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