Synthesis and characterization of metal-loaded clay-based materials for reactive adsorption applications.
Item
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Title
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Synthesis and characterization of metal-loaded clay-based materials for reactive adsorption applications.
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Identifier
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AAI3214539
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identifier
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3214539
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Creator
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Nguyen-Thanh, Danh.
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Contributor
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Adviser: Teresa J. Bandosz
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Date
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2006
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Physical
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Abstract
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Clay-based adsorbents were first synthesized by exchanging a nonporous clay with iron, zinc, or copper cations. In the case of iron, while most hydrated cations were located in the clay gallery, oxocations were present both in the gallery and on the outer clay surface. In both cases, the fraction of iron available for surface reaction was limited, as the hydrated cations were unreachable in the gallery and oxocations formed large clusters.;The initial clay was then intercalated with alumina pillars which resulted in the presence of micropores in the gallery. The pillared clay was subsequently loaded with iron, zinc, or copper that entered the material's pores. Iron clogged the micropores, which reduced its availability, while copper was the most widely spread metal in the material's pores.;Using organic surfactants, the clay was also intercalated with silica and the resulting porous clay heterostructures had a higher porosity and wider micropores than the pillared clays. Metal loading created some new mesoporosity, due to the deposition of silica on the clay surface as a consequence of cation-exchange. Carbon deposits resulting from the thermal degradation of the surfactants during the materials' preparation seem to hinder the metals' accessibility in these materials.;These clay materials then served as templates for the synthesis of carbons via carbonization of sucrose within the pore space followed by the template removal by acid treatment. The carbons were partial replicas of their inorganic matrices, with micropores of identical sizes. The carbons appeared ordered on a short-scale, as graphene layers were stacked in parallel and formed micropores. These stacks adopt a house-of-cards structure, resulting in mesoporous voids. Due to acid treatment, the metal content of these carbons was low, except in the case of iron present under acid-resistant forms.;Cation-exchanged clays were finally used as binders of a porous activated carbon, improving the mechanical properties of the carbon. While a slight decrease in porosity was observed due to mass dilution effect, migration of metal from the clay to the carbon's micropores took place. That combined effect of metal and porosity gives potentially efficient adsorbents and catalysts.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
