345 research outputs found
FUEL-BASED POLLUTANTS REMOVAL FROM WATER: STRUCTURAL EVIDENCES OF ADSORPTION INTO HIGH SILICA ZEOLITES
No full textThe enormous and rapid development of the chemical and agrochemical industries during the last century has resulted in the release of a large number of chemical compounds into the environment. Aquatic ecosystems are especially vulnerable because water bodies are frequently used, directly or indirectly, as recipients of potentially toxic liquids and solids from domestic, agricultural and industrial wastes. Removal of fuel-based compounds from natural water is of considerable interest due to the harmful effects of these pollutants on the environment, even at very low concentration [1]. Among this category of compounds, toluene, 1,2-dichloethane and methyl-tert-buthyl-ether are of special relevance since are toxic and commonly found in natural water. Research on hydrocarbon removal has been mainly focussed on single components from air matrix, whereas the studies involving aqueous dilute solutions are few [2-5]. Adsorption is a reliable alternative to eliminate these organic compounds from wastewaters because of the flexibility of the system, low energy and cheap operation costs. Moreover, the process does not induce the formation of oxidation intermediates which are, to date, mostly unknown. The presence of natural organic matter can significantly affect organic pollutant adsorption by either competing for adsorption sites, or restricting access to (micro)pores.
This work is a part of a wider project whose purpose is to study the interaction and mobility of ground water pollutants adsorbed in the zeolites pores. Organophilic synthetic zeolites which are cheap and available on the market, differing in topology, channel systems and free window apertures, and fuel-based-pollutants differing in chemical properties and molecular dimensions, were tested. In particular, structural evidences of adsorption from dilute solutions into organophilic zeolite as well as the competitive role of humic acid monomers, the effect of the temperature in the adsorption processes will be discussed. The selected adsorbents were commercial as-synthesized hydrophobic ZSM-5 and Y zeolites with high SiO2/Al2O3. Kinetics and adsorption isotherm batch data were obtained via Headspace Solid Phase Microextraction-GC. X-ray powders patterns were collected before and after adsorption on a Bruker D8 Advance diffractometer equipped with SOL-X detector. Thermal analyses (TG and DTA) were performed in air up to 900°C at 10°C/min. Infrared spectra were collected on a Thermo Electron Corporation FT Nicolet 5700 Spectrometer. This combined diffractometric, thermogravimetric, chromatographic and spectroscopic study allowed us to: 1) measure the sorption capacity of hydrophobic zeolite materials weighed against organic pollutants dissolved in water; 2) characterise the structure after contaminants adsorption; 3) localise the organic species in the zeolite channel systems; 4) highlight the role of humic acid monomers in the pollutants removal; 5) probe the interaction between the adsorbate and the zeolite framework. The very favorable adsorption kinetics along with the effective and highly irreversible adsorption into zeolite pores make these cheap and environmental friendly materials applicable for the treatment of water contaminated with fuel-based pollutants.
References. [1] Trindade P.V.O., Sobral L.G. , Rizzo A.C.L., Leite S.G.F. (2005) Chemosphere, 58, 515–522; [2] L.Abu-Lail, J. A. Bergendahl, R. W. Thompson, Journal of Hazardous Materials 2010, 178, 363-369. [3] Martucci A., Pasti L., Nassi M., Alberti A., Arletti R., Bagatin R., Vignola R., Sticca, R. (2012) Micropor. Mesopor. Mater. 148, 174-183. [4] Arletti, R., Martucci, A., Alberti, A., Pasti, L., Nassi, M., Bagatin, R. (2012) Journal of Solid State Chemistry, 194, 135-142.[5] Pasti L., Martucci A., Nassi M., Cavazzini A., Alberti A., Bagatin, R. (2012) Microporous and Mesoporous Materials, 160, 182-193
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)
The Arabic Manuscripts on Grammar from the Kahle Fonds: Some Research Proposals
No full textThe Paul Kahle Fonds, preserved at the University of Turin, gather together printed books,
manuscripts and papers related to the activities of Paul Ernst Kahle (1875-1964) as an orientalist scholar. In the
Islamic manuscripts section, a big number of them deal with the Arabic grammar tradition. Most of the works
included in the manuscripts date back to the post-classical age (from XI to XIX century), with a particular
concentration in the XIV century. Almost all the works are commentaries of first or second order to previous
treatises by well known grammarians. From a point of view both chronological and structural, these works can
be placed in the pedagogic stage of the Arabic grammar tradition, characterized by a change in the organisation
of the topics and in the way topics relating to syntax or morphology were dealt with. On the basis of two main
perspectives, some clusters are identifiable to illustrate the different relations one can recognize between the
original independent treatises and their commentaries or between commentaries of the same/different order. In
such a way, scholars are also allowed to check for possible and more complex inter-text relationships, to
highlight mutual influences among authors and/or commentators, to investigate topics or methods peculiar to one
author/commentator and to follow up their developments
From ʿilm al-naḥw to maʿānī l-naḥw in ʿAbd al-Qāhir al-Ǧurǧānī’s linguistic thinking
No full textʿAbd al-Qāhir al-Ǧurǧānī (d. 471/1078) is today known for being the author of two fundamental treatises: Dalāʾil al- ʾiʿǧāz and ʾAsrār al-balāġa. The first one is about ʿilm al-maʿānī, a discipline labelled by some modern scholars as “syntax semantics”, “grammatical semantics”, “syntax stylistics” and even as “functional grammar”. The second treatise is about the study of rhetoric (ʿilm al-balāġa). However, most of Ǧurǧānī’s works are about grammar (naḥw), dealing with topics such as grammatical operativity (ʿamal), desinential inflection (ʾiʿrāb), noun and verb morphology, etc. As a rule, ancient and modern scholars have kept separate the two methods of his linguistic thinking: the descriptive and at times pedagogical approach; and the theoretical, semantic-oriented approach, concerning which Ǧurǧānī is acknowledged among the pioneers. Thus, his works would have been addressed to various kinds of readers and have known a different fortune depending on the time, the geographical area and the cultural environment of their reception. It is, however, possible to suppose a continuity in Ǧurǧānī’s linguistic thinking connecting the two groups of works. Following this line of enquiry, one is supposed to find in his grammatical dissertations the seeds of what would have become his “theory of meaning” within the Dalāʾil al-ʾiʿǧāz
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
The Arabic Manuscripts on Grammar from the Kahle Fonds: Some Research Proposals
No full textThe Paul Kahle Fonds, preserved at the University of Turin, gather together printed books, manuscripts and papers related to the activities of Paul Ernst Kahle (1875-1964) as an orientalist scholar. In the Islamic manuscripts section, a big number of them deal with the Arabic grammar tradition. Most of the works included in the manuscripts date back to the post-classical age (from XI to XIX century), with a particular concentration in the XIV century. Almost all the works are commentaries of first or second order to previous treatises by well known grammarians. From a point of view both chronological and structural, these works can be placed in the pedagogic stage of the Arabic grammar tradition, characterized by a change in the organisation of the topics and in the way topics relating to syntax or morphology were dealt with. On the basis of two main perspectives, some clusters are identifiable to illustrate the different relations one can recognize between the original independent treatises and their commentaries or between commentaries of the same/different order. In such a way, scholars are also allowed to check for possible and more complex inter-text relationships, to highlight mutual influences among authors and/or commentators, to investigate topics or methods peculiar to one author/commentator and to follow up their developments
Il Mi’at ‘āmil fī an-naḥw di ‘Abd al-Qāhir al-Ğurğānī. Un trattato didattico sugli operanti grammaticali in arabo
No full textIl volume contiene un'edizione critica del breve trattato di ‘Abd al-Qāhir al-Ğurğānī sugli operanti grammaticali intitolato Mi’at ‘āmil fī an-naḥw (Centro operanti grammaticali).The so-called theory of grammatical opertors represents one of the cornerstones of the Arabic grammatical tradition, a fundamental chapter in the works of the classical age and the following centuries. Through it, the grammarians explained what was to them the distinctive feature of their language model, that is, the inflection of nouns and verbs. The Mi’at ‘āmil fī an-naḥw (One Hundred Grammatical Operators) by ‘Abd al-Qāhir al-Ğurğānī is a short treatise of the 11th century which aims to provide a classification of such operators, enriched by some semantic clarifications. It is considered one of the first treatises of the “pedagogical phase” of the Arabic grammatical tradition, and among the most commented by the subsequent grammarians. From a linguistic point of view, the relevance of the work arises in so far as it is integrated with the other grammatical treatises of the same author. In this way, it is possible to grasp the theoretical approach given to the operativeness issue, and reflect on the relationship between syntax and meaning, whose full formulation would have appeared in the theory of speech as we find it in the semantic-rhetorical works, for which al-Ğurğānī is above all known today
Boron removal from water: Needs, challenges and perspectives
No full textBoron is often present in water streams to be treated to match final user specifications or environmental restrictions. It can not be removed by conventional water treatments and its separation still remains an issue. An overview on this topic is provided. Needs are identified considering information regarding boron level effect on environment, human health and activities. Challenges are described envisaging boron main physical-chemical properties and current approaches for its removal. Perspectives are sketched pointing to possible technology improvements
Enhancements in ElectroKinetic Remediation Technology: Focus on hydraulic management and wastewater recovery
No full textThe ElectroKinetic Remediation Technology (EKRT), when applied to an earthy matrix, is generally targeted to the extraction of one or more pollutants, often inorganic and typically belonging to the category of heavy metals. The technique exploits the effects caused by the application of an electric field for allowing the mobilization of the targeted pollutants, whose displacement is often facilitated by the use of suitable chemicals, which act as complexing agents. The EKRT represents a very promising approach, as it is able to produce results comparable to those of other on/off-site interventions, though with appreciably higher levels of acceptability. Moreover, in spite of expectations (which are substantially based on the high use of energy and consumables), we showed that, once properly configured, the EKRT may represent an excellent choice even when judged based on the environmental sustainability. With the present study, we aim at discussing further the plant configuration, with a special focus on the water management. In fact, as anticipated in our previous communications, the modifications that we implemented in our EKRT approach allow presenting it as an electrochemically-assisted soil flushing. Several are the elements of innovation introduced, which proved to increase the effectiveness of the remediation, but at the price of a potentially very high water (and energy) consumption. It is therefore important to have an advanced water management system, preferably coupled with a reliable wastewater recovery system in order to avoid the waste of water resources, and consequently keep down costs as well as the ecological footprint related with the implementation of this technology, thus maximizing its benefits
A fast code using nonmagnetic measurements for RFX current and magnetic field profile reconstruction
No full textFast identification techniques of the plasma internal magnetic structure are needed for the real time control of the plasma current distribution in magnetic confinement devices. In this paper, a fast identification code using plasma internal nonmagnetic measurements is proposed and applied to the reversed field pinch experiment. The identification tool is based on a force-free ideal magnetohydrodynamic equilibrium model, using a parametric radial profile for the magnetic field and current density. A set of constraints on the internal magnetic distribution are derived from the Faraday rotation data given by a five-chord polarimeter, assuming the plasma density as given by an interferometric diagnostic. The code execution time is about a few second
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