Contribution à l'étude de l'adsorption physique de gaz sur les nanotubes de carbone mono- et multiparois PDF Download
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Author: Moulay-Rachid Babaa
Publisher:
ISBN:
Category :
Languages : fr
Pages : 164
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Book Description
Ce travail porte sur l'étude de l'adsorption de Kr, Xe et CCl4 sur des nanotubes de carbone mono- et multiparois. La comparaison des isothermes et des énergies d'adsorption de molécules simples avec celles obtenues sur le graphite nous a permis de préciser les différents sites d'adsorption et l'influence de la courbure des plans de graphène. Nous avons caractérisé l'effet de deux techniques d'ouverture des nanotubes sur leurs propriétés et leurs capacités d'adsorption. L'efficacité de la technique mécanique a été étudiée. Nous avons estimé la fraction de la surface interne accessible et la proportion des impuretés introduites par ce procédé. Différents modes d'arrangement des molécules des trois gaz à l'intérieur des tubes monoparois en fonction de leurs diamètres moléculaires ont été mis en évidence. Les nanotubes multiparois ouverts aux extrémités par une oxydation sélective, ont été également caractérisés. La comparaison des isothermes d'adsorption avant et après traitement et l'analyse par MET nous ont permis de déterminer le mécanisme de l'oxydation, son efficacité ainsi que l'influence de ce traitement sur la surface et la structure des nanotubes.
Author: Moulay-Rachid Babaa
Publisher:
ISBN:
Category :
Languages : fr
Pages : 164
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Book Description
Ce travail porte sur l'étude de l'adsorption de Kr, Xe et CCl4 sur des nanotubes de carbone mono- et multiparois. La comparaison des isothermes et des énergies d'adsorption de molécules simples avec celles obtenues sur le graphite nous a permis de préciser les différents sites d'adsorption et l'influence de la courbure des plans de graphène. Nous avons caractérisé l'effet de deux techniques d'ouverture des nanotubes sur leurs propriétés et leurs capacités d'adsorption. L'efficacité de la technique mécanique a été étudiée. Nous avons estimé la fraction de la surface interne accessible et la proportion des impuretés introduites par ce procédé. Différents modes d'arrangement des molécules des trois gaz à l'intérieur des tubes monoparois en fonction de leurs diamètres moléculaires ont été mis en évidence. Les nanotubes multiparois ouverts aux extrémités par une oxydation sélective, ont été également caractérisés. La comparaison des isothermes d'adsorption avant et après traitement et l'analyse par MET nous ont permis de déterminer le mécanisme de l'oxydation, son efficacité ainsi que l'influence de ce traitement sur la surface et la structure des nanotubes.
Author: Boris Dzyubenko
Publisher: Boris Dzyubenko
ISBN:
Category : Science
Languages : en
Pages : 180
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Book Description
Rare gas adsorption was studied on suspended individual single walled carbon nanotubes and graphene. The devices were fabricated as field effect transistors. Adsorption of N2 and CO, which formed a Root 3 X Root 3 commensurate solid monolayer, produced a dramatic reduction of the two-terminal conductance of graphene by as much as a factor of three. This effect is possibly connected with the opening of a band gap expected to occur in such structures.
Author: Maria Letizia Terranova
Publisher: CRC Press
ISBN: 9814316431
Category : Technology & Engineering
Languages : en
Pages : 500
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Book Description
Research in adsorption of gases by carbon nanomaterials has experienced considerable growth in recent years, with increasing interest for practical applications. Many research groups are now producing or using such materials for gas adsorption, storage, purification, and sensing. This book provides a selected overview of some of the most interesting scientific results regarding the outstanding properties of carbon nanomaterials for gas adsorption and of interest both for basic research and technological applications. Topics receiving special attention in this book include storage of H, purification of H, storage of rare gases, adsorption of organic vapors, gas trapping and separation, and metrology of gas adsorption.
Author: Boris Dzyubenko
Publisher:
ISBN:
Category :
Languages : en
Pages : 167
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Book Description
Rare gas adsorption was studied on suspended individual single walled carbon nanotubes and graphene. The devices were fabricated as field effect transistors. Adsorption on graphene was studied through two-terminal conductance. On nanotube devices adsorption was studied through conductance while the coverage (density) of the adsorbates was determined from the mechanical resonance frequency shifts. The adsorbed atoms modified the conductance of the nanotube field effect transistors, in part through charge transfer from the adsorbates to the nanotube. By tracking the shifts of conductance as a function of gate voltage, G=G(Vg), and comparing these shifts with the periodicity of the Coulomb blockade oscillations we quantified the charge transfer to the nanotubes with high accuracy. For all studied gases (He, Ar, Kr, Xe, N2, CO, and O2) the charge transfer had a similar magnitude and was rather small, on the order of 10^-5 to 10^-3 electrons per adsorbed atom. The nanotube devices displayed two classes of adsorption behavior. On some devices the monolayers exhibited first-order phase transitions analogous to those that occur in adsorbed monolayers on graphite. On other devices phase transitions within the adsorbed monolayers were absent. We present evidence that a highly uniform layer of contaminants deposits on the surface of suspended nanotube devices either upon cooldown in the cryostat or at room temperature from air. These contaminants modify the adsorption behavior preventing the adsorbed monolayers from exhibiting the first order phase transitions expected to occur on a clean surface. A similar type of contamination leading to virtually identical effects occurs on suspended graphene. In the low coverage regions of isotherms on nanotubes we observe Henry's law behavior, demonstrating a high uniformity of the surface and allowing us to accurately determine the single particle binding energy to this surface. The determined binding energies were 776+-10 K for Ar, and 997+-37 K for Kr. In the second part of the dissertation we present the first measurements of adsorption on a pristine graphene surface, exposed through aggressive electric current annealing. On graphene the rare gas adsorbates form monolayers with phases analogous to those on graphite, but with phase transitions occurring at slightly higher pressures due to a reduction of binding energy. The condensations of monolayers with phases not commensurate with the graphene lattice resulted in a slight shift of the charge neutrality point of monolayer graphene corresponding to a change of carrier concentration on the order of 10^9 e/cm^2. Adsorption of N2 and CO, which formed a Root 3 X Root 3 commensurate solid monolayer, produced a dramatic reduction of the two-terminal conductance of graphene by as much as a factor of three. This effect is possibly connected with the opening of a band gap expected to occur in such structures. We observe hysteretic behavior in the adsorbed Root 3 X Root 3 commensurate monolayers on freestanding graphene, which is likely due to the interaction of two adsorbed monolayers on opposite surfaces of the graphene sheet.
Author: Muris
Publisher:
ISBN:
Category :
Languages : fr
Pages : 248
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Book Description
Author: Carlos P. Bergmann
Publisher: Springer
ISBN: 3319188755
Category : Technology & Engineering
Languages : en
Pages : 126
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Book Description
This book presents a summary of the current use of carbon nanomaterials for water treatment, drug delivery, systems and nanosensors. The first chapter elucidates the adsorption process phenomenon. Also, the properties of different carbon nanomaterials for adsorption applications are covered. The third chapter presents the kinetic and equilibrium models of adsorption, processing of experimental data and adsorption process peculiarities. Environmental and biological applications of carbon nanomaterials are listed in the last chapter. This book is written from an application-oriented perspective and is useful for all those interested in nanoadsorbents.
Author: Joseph-Marie de Kalbermatten
Publisher:
ISBN:
Category : Adsorption
Languages : fr
Pages : 96
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Book Description
Author: EL HABIB.. IBNASS
Publisher:
ISBN:
Category :
Languages : fr
Pages :
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Book Description
CE TRAVAIL EST UNE CONTRIBUTION A L'ETUDE DE L'ADSORPTION PHYSIQUE ET DE LA COADSORPTION DES MOLECULES H#2 ET D#2 DANS UN CRISTAL MICROPOREUX LA ZEOLITHE NAA, PAR MICROGRAVIMETRIE ET SPECTROMETRIE INFRAROUGE. LA BANDE DE VIBRATION FONDAMENTALE DE CES MOLECULES DIATOMIQUES HOMOPOLAIRES, INTERDITE EN IR POUR LA PHASE GAZEUSE, APPARAIT LORSQUE CES MOLECULES SONT ADSORBEES A L'INTERIEUR DES CAVITES. LA COMPARAISON DES ISOTHERMES DES GAZ PURS A MONTRE QUE LE RAPPORT DES TAUX D'ADSORPTION DE D#2 SUR H#2 EST EGAL A 1.1. CECI EST EXPLIQUE PAR LA DIFFERENCE DES COVOLUMES DE CES DEUX MOLECULES. LA MESURE DES INTENSITES DES BANDES INFRAROUGES CONDUIT A LA DETERMINATION DE LA VALEUR DU CHAMP ELECTRIQUE DANS LA CAVITE ZEOLITHIQUE. DANS LE CAS DE LA COADSORPTION D'UN MELANGE GAZEUX EQUIMOLAIRE H#2-D#2, NOUS AVONS MESURE LE FACTEUR DE SEPARATION ALPHA EN FONCTION DE LA PRESSION ET DE LA TEMPERATURE A PARTIR DE LA SURFACE DES BANDES INFRAROUGES DES MOLECULES ADSORBEES. ON CONSTATE QUE ALPHA EST SUPERIEUR AU RAPPORT DES ISOTHERMES DES GAZ PURS, ET PASSE DE 1.5 A 3 QUAND ON ABAISSE LA TEMPERATURE DE 120 A 77 K
Author: Eduardo J. Bottani
Publisher: Elsevier
ISBN: 0080559425
Category : Technology & Engineering
Languages : en
Pages : 773
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Book Description
Adsorption by Carbons covers the most significant aspects of adsorption by carbons, attempting to fill the existing gap between the fields of adsorption and carbonaceous materials. Both basic and applied aspects are presented. The first section of the book introduces physical adsorption and carbonaceous materials, and is followed by a section concerning the fundamentals of adsorption by carbons. This leads to development of a series of theoretical concepts that serve as an introduction to the following section in which adsorption is mainly envisaged as a tool to characterize the porous texture and surface chemistry of carbons. Particular attention is paid to some novel nanocarbons, and the electrochemistry of adsorption by carbons is also addressed. Finally, several important technological applications of gas and liquid adsorption by carbons in areas such as environmental protection and energy storage constitute the last section of the book. - The first book to address the interplay between carbonaceous materials and adsorption - Includes important environmental applications, such as the removal of volatile organic compounds from polluted atmospheres - Covers both gas-solid and liquid-solid adsorption
Author: Michel Roques
Publisher:
ISBN:
Category :
Languages : fr
Pages : 288
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Book Description
L'ETUDE DES TEXTURES ULTRAMICROPOREUSES PAR ADSORPTION ET DIFFUSION DE N::(2), O::(2) ET CO::(2) A PRINCIPALEMENT PORTE SUR LES ADSORBANTS QUI ONT LA PARTICULARITE DE NE PAS ADSORBER L'AZOTE A -195**(O)C (CARBONES OU TAMIS MOLECULAIRE 4A)
