Interaction of ozone with adsorbent charcoals

Deitz, Victor R.; Bitner, J.L.

doi:10.1016/0008-6223(73)90079-1

Cited by 54 publications

(38 citation statements)

References 13 publications

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“…al. [22] also report a continuous decomposition of ozone treated charcoals at temperatures greater than 77K. Partial preservation of surface activity by storage of the treated carbon in an inert gas atmosphere suggests some component of air aids in the decomposition of surface functional groups.…”

Section: Resultsmentioning

confidence: 81%

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High capacity mercury adsorption on freshly ozone-treated carbon surfaces

Manchester

Wang

Külaots

et al. 2008

Carbon

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A set of carbon materials was treated by a choice of common oxidizers to investigate the mercury capture capacities at varying temperature conditions. It was found that ozone treatment dramatically increases the mercury capture capacity of carbon surfaces by factors up to 134, but the activity is easily destroyed by exposure to the atmosphere, to water vapor, or by mild heating. Freshly ozonetreated carbon surfaces are shown to oxidize iodide to iodine in solution and this ability fades with aging. FTIR analysis shows broad C-O stretch features from 950 to 1300 cm −1 , which decay upon atmospheric exposure and are similar to the C-O-C asymmetric stretch features of ethylene secondary ozonide. The combined results suggest that the ultra-high mercury capture efficiency is due to a subset of labile C-O functional groups with residual oxidizing power that are likely epoxides or (epoxide-containing) secondary ozonides. The results open the possibility for in situ ozonolysis to create high-performance carbon-based Hg sorbents.

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Section: Resultsmentioning

confidence: 81%

“…The capacity increase for the microporous activated carbon is much less than for the nonmicroporous carbon black and mesoporous carbon, likely due to micropore blockage by oxygen containing functional groups. Ozonolysis of microporous carbons has been shown to leads to a decrease in surface area because of pore blockage [16,22].…”

Section: Resultsmentioning

confidence: 99%

High capacity mercury adsorption on freshly ozone-treated carbon surfaces

Manchester

Wang

Külaots

et al. 2008

Carbon

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“…En una primera etapa, el ozono se adiciona al doble enlace formando un intermedio inestable denominado ozónido primario (I). Posteriormente, este ozónido primario pasa al ozónido secundario, mucho más estable, denominado molonozónido a través del zwitterion [22]. En la ruptura del ozónido secundario se generan grupos superficiales oxigenados (II).…”

Section: Resultados Y Discusiónunclassified

“…Los resultados obtenidos se corresponden con los observados por otros autores que reportan variaciones en el área superficial aparente de muestras de carbón tratadas con ozono [22,26]. Se plantea que en una primera etapa el comportamiento es similar al proceso de formación de los carbones activados donde se suministra un gas oxidante con el objetivo de abrir los poros en la estructura del carbón y, por consiguiente, se incrementa o mantiene el área superficial aparente.…”

Section: Tiempo De Ozonización Min 30 60 120unclassified

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Impacto del tratamiento con ozono sobre las propiedades superficiales del carbón activado

Váldes¹,

Sánchez‐Polo

Zaror³

2011

Ingeniare. Rev. chil. ing.

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RESUMENEl uso conjunto de ozono y carbón activado para tratar efluentes tóxicos ha sido demostrado recientemente. Sin embargo, existen dudas acerca del efecto del ozono sobre las propiedades del carbón activado. En este artículo se presentan resultados sobre la modificación de las propiedades superficiales de un carbón activado comercial por la acción del ozono durante diferentes tiempos de exposición. Las propiedades químicas superficiales del carbón activado fueron evaluadas utilizando las técnicas de neutralización selectiva, desorción térmica programada (DTP) y el pH del punto de carga cero. Las características texturales fueron evaluadas mediante microscopía electrónica de barrido. El área superficial aparente, el volumen de microporos y mesoporos fueron obtenidos a partir de las isotermas de adsorción de nitrógeno a 77 K. Las propiedades adsortivas fueron caracterizadas por el índice de adsorción de azul de metileno. Los resultados demuestran que los grupos superficiales oxigenados presentes en el carbón activado se modifican producto del tratamiento con el ozono. A mayores dosis de ozono, el carbón sufre mayor oxidación y se incrementan los grupos ácidos en especial los grupos carboxílicos, mientras que el pH de punto de carga cero disminuye. El área BET, así como el volumen de microporos disminuyen al igual que el poder de adsorción de azul de metileno.Palabras clave: Carbón activado, ozono, grupos ácidos, grupos básicos, propiedades químicas, propiedades texturales. ABSTRACT

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Carbons

Schlögl

2008

Handbook of Heterogeneous Catalysis

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The element carbon plays a multiple role in heterogeneous catalysis. In homogeneous catalysis it occurs of course as the most prominent constituent of ligand systems and will be treated as such there. Carbon-containing molecules are, in most catalytic applications, the substrates of the process under consideration. Deposits and polymers of carbon often occur as poisons on catalysts. Carbon deposition is the most severe problem in certain zeolite applications. In hydrogenation reactions carbon deposits are thought to act as modifiers for the activity of the catalyst and to provide selectivity by controlling the hydrogenationdehydrogenation activity of the metal part of the catalyst. Carbon deposits are even thought to constitute part of the active sites in some cases. Carbon is a prominent catalyst support material as it allows the anchoring of metal particles on a substrate which does not exhibit solid acid-base properties. Carbon is finally a catalyst in its own right allowing the activation of oxygen and chlorine for selective oxidation, chlorination and de-chlorination reactions. These multiple roles of the element carbon are in parallel with a complex structural chemistry giving rise to families of chemically vastly different modifications of the element. It is a special characteristic of carbon chemistry that many of these modifications cannot be obtained as phase-pure materials. This limits the exact knowledge of physical and chemical properties to a few archetype modifications, namely graphite and diamond. The reason for this poor definition of materials is found in the process of its formation. This is comprised of difficult to control polymerisation reactions. Such reactions will occur also in catalytic reactions with small organic molecules. The nature of carbon deposits will therefore reflect all the complexity of the bulk carbon materials. It is one aim of this article to describe the structural and chemical complexity of "carbon" or "soot" in order to provide an understanding of the frequently observed complexity of the chemical reactivity (e.g. in re-activation processes aiming at an oxidative removal of deposits). The surface chemistry of carbon which determines its interfacial properties is a rich field as a wide variety of surface functional groups are known to exist on carbon. The by far most important family of surface functional groups are those involving oxygen. Other prominent heteroatoms on the surface are hydrogen and nitrogen. This article focusses on the description and characterisation of oxygen surface functional groups. In the final section, selected case studies of carbon chemistry in catalysis will be discussed in order to illustrate characteristic properties of carbon materials as wanted or unwanted components in catalytic systems. Regarding the literature on basic properties of carbon materials, the reader is referred to the extensive collection of review papers published in the series Chemistry and Physics of Carbon. Editors P.L.

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Interaction of ozone with adsorbent charcoals

Cited by 54 publications

References 13 publications

High capacity mercury adsorption on freshly ozone-treated carbon surfaces

High capacity mercury adsorption on freshly ozone-treated carbon surfaces

Impacto del tratamiento con ozono sobre las propiedades superficiales del carbón activado

Carbons

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