Download or read book Synthesis of Ordered Mesoporous Silica and Alumina with Controlled Macroscopic Morphologies written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis investigates the synthesis of ordered mesoporous silica and alumina materials with unique microstructures and different morphologies using novel approaches based on template-assisted synthesis and chemical vapor deposition (CVD) techniques and their potential use in polymer reaction application. Template-assisted growth of mesoporous silica under acidic and quiescent conditions at an oil-water interface can generate mesostructured silica with fibrous and non-fibrous morphologies. Fibers are obtained due to slow and one-dimensional diffusion of precursors through the interface. Variation in conditions can alter the axial growth of silica and yield non-fibrous shapes. Fibers grow from their base attached to the interface and coalesce to form fibers with larger diameters. Gas transport in silica fibers is governed by Knudsen and surface diffusion mechanisms. Surface diffusion contributes to 40% of the flow reflecting highly smooth pores. Real Knudsen and surface diffusivities are in the order of 10E-3 and 10E-5 cm2̂/s respectively. The one-dimensional mesopores are 45 time longer than the fiber length and align helically around the fiber axis with a pitch of 1.05 micron. Mesoporous silica membranes were prepared by a novel counter diffusion self assembly (CDSA) approach. This approach introduces the precursors from the opposite sides of a hydrophobic supports and yields silica plugs grown within its pores. Silica plugs grow with thickness of 0.5 mm and have a mesoporous structure. Such mechanically strong membrane is potential in protein separation and polymer reaction applications. Mesoporous membranes with controlled pore microstructure can be also obtained using cyclic CVD modification of straight 20 nm pore alumina membranes. Leaving residual of precursors in the pore after introduction of each precursor causes deposition of alumina in a fractal structure suitable for gas separation. Purging the pore after each precursor causes deposition in atomic layer with cylindrical mesopores suitable for membrane reaction applications. Titanocene-supported MCM-41 was used as molecular extruder for preparation of 60 nm polyethylene nascent fibers with extended-chain crystalline structures. The nascent fibers aggregate into 1-30 ư m microfibers which further aggregate into fiber bundles. Mechanical properties, measured for the first time, demonstrated an improved tensile strength of the polyethylene product compared to commercial polyethylene fibers.

Download or read book Synthesis and Characterization of Ordered Mesoporous Silica with Controlled Macroscopic Morphology for Membrane Applications written by Shriya Seshadri and published by . This book was released on 2011 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ordered mesoporous materials have tunable pore sizes between 2 and 50 nm and are characterized by ordered pore structures and high surface areas (~1000 m2/g). This makes them particularly favorable for a number of membrane applications such as protein separation, polymer extrusion, nanowire fabrication and membrane reactors. These membranes can be fabricated as top-layers on macroporous supports or as embedded membranes in a dense matrix. The first part of the work deals with the hydrothermal synthesis and water-vapor/oxygen separation properties of supported MCM-48 and a new Al-MCM-48 type membrane for potential use in air conditioning systems. Knudsen-type permeation is observed in these membranes. The combined effect of capillary condensation and the aluminosilicate matrix resulted in the highest separation factor (142) in Al-MCM-48 membranes, with a water vapor permeance of 610-8mol/m2Pas. The second part focuses on synthesis of embedded mesoporous silica membranes with helically ordered pores by a novel Counter Diffusion Self-Assembly (CDSA) method. This method is an extension of the interfacial synthesis method for fiber synthesis using tetrabutylorthosilicate (TBOS) and cetyltrimethylammonium bromide (CTAB) as the silica source and surfactant respectively. The initial part of this study determined the effect of TBOS height and humidity on fiber formation. From this study, the range of TBOS heights for best microscopic and macroscopic ordering were established. Next, the CDSA method was used to successfully synthesize membranes, which were characterized to have good support plugging and an ordered pore structure. Factors that influence membrane synthesis and plug microstructure were determined. SEM studies revealed the presence of gaps between the plugs and support pores, which occur due to shrinking of the plug on drying. Development of a novel liquid deposition method to seal these defects constituted the last part of this work. Post sealing, excess silica was removed by etching with hydrofluoric acid. Membrane quality was evaluated at each step using SEM and gas permeation measurements. After surfactant removal by liquid extraction, the membranes exhibited an O2 permeance of 1.65x10-6mol/m2. Pa.s and He/O2 selectivity of 3.30. The successful synthesis of this membrane is an exciting new development in the area of ordered mesoporous membrane technology.

Download or read book Ordered Mesoporous Silica written by Barbara Platschek and published by . This book was released on 2007 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2005 with total page 858 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis Modification and Characterization of Ordered Mesoporous Silica Particles for Controlled Drug Release written by Shewaye Yismaw Wubetu and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis Characterization and Structure Control of Ordered Mesoporous Silica Nanoparticles written by Teeraporn Suteewong and published by . This book was released on 2011 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ordered mesoporous silica materials are characterized by uniform and tunable pore size, high surface area and large pore volume. In particular, nano-sized ordered mesoporous silica particles have drawn interest from several fields, including biorelated areas, because silica is benign, possesses chemical stability and can be integrated with other materials. Structural aspects, such as pore connectivity, geometry and pore size are known to govern materials performance. Extensive efforts have been devoted to synthesize mesoporous silica particles with different structures, functionalities and sizes. In contrast, only a small number of studies so far have concentrated on the formation mechanism of these particles. This is hence the focus of the present dissertation. The first part reports on the synthesis and characterization of ordered mesoporous silica nanoparticles with and without embedded magnetic nanoparticles. The formation mechanism of silica nanocomposites is investigated by capturing particle formation at different time points during the synthesis. A combination of transmission electron microscopy (TEM) and small angle x-ray scattering (SAXS) is used to characterize the structure evolution of resulting materials. Incorporating organic moieties into the silica matrix provides additional functionalities to ordered mesoporous silica nanoparticles. However, it often leads to disordered pore structure or pore blockage. The second part demonstrates the preparation of aminated and ordered mesoporous silica nanoparticles using a cocondensation method. Increasing the amount of aminosilane in the synthesis feed causes a structural transition of organically modified particles from hexagonal to cubic. Pore size of ordered mesoporous silica and aminated ordered mesoporous silica nanoparticles can be tailored by the addition of a swelling agent during the synthesis. The structural transformation from hexagonal to cubic is also observed in the latter case, albeit at different amino silane concentrations. The final part reports on the internalization of nanoparticles into cells. Fluorescent aminated mesoporous silica nanoparticles are first prepared and then coated with poly(ethylene glycol) to improve particle stability and lower protein adsorption. Dye-labeled aminated mesoporous silica nanoparticles are spontaneously internalized by cells.

Download or read book Advanced Water Treatment written by Mika Sillanpaa and published by Elsevier. This book was released on 2020-01-08 with total page 694 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced Water Treatment: Adsorption discusses the application of adsorption in water purification. The book reviews research findings on the preparation of five different nano/microcellulose-based adsorbents, their characterization, the study of adsorption kinetics and isotherms, the determination of adsorption mechanisms, and an evaluation of adsorbents’ regeneration properties. The book describes modification microfibrillated cellulose (MFC), the use of succinic anhydride modified mercerized nanocellulose, and aminosilane and hydroxyapatite modified nanostructured MFC for the removal of heavy metals from aqueous solutions. Final sections describe the use of aminosilane, epoxy and hydroxyapatite modified MFC as a promising alternative for H2S removal from aqueous solutions, along with new findings on the adsorption properties of carbonated hydroxyapatite modified MFC as multifunctional adsorbent for the removal of both cations and anions ions from water. Includes the most recent research on advanced water treatment by adsorption Provides the latest updates on novel absorbents for water purification Describes REE removal using various absorbents Covers a wide range of methods and their integration

Download or read book Nanocasting written by An-Hui Lu and published by Royal Society of Chemistry. This book was released on 2010 with total page 279 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanostructured materials with tailored properties are regarded as a fundamental element in the development of future science and technology. Research is still ongoing into the nanosized construction elements required to create functional solids. The recently developed technique, nanocasting, has great advantage over others in terms of the synthesis of special nanostructured materials by the careful choice of suitable elements and nanoengineering steps. This new book summarizes the recent developments in nanocasting, including the principles of nanocasting, syntheses of novel nanostructured materials, characterization methods, detailed synthetic recipes and further possible development in this area. The book focuses on the synthesis of porous solids from the viewpoint of methodology and introduces the science of nanocasting from fundamental principles to their use in synthesis of various materials. It starts by outlining the principles of nanocasting, requirements to the templates and precursors and the tools needed to probe matter at the nanoscale level. It describes how to synthesize nano structured porous solids with defined characteristics and finally discusses the functionalization and application of porous solids. Special attention is given to new developments in this field and future perspectives. A useful appendix covering the detailed synthetic recipes of various templates including porous silica, porous carbon and colloidal spheres is included which will be invaluable to researchers wanting to follow and reproduce nanocast materials. Topics covered in the book include: * inorganic chemistry * organic chemistry * solution chemistry * sol-gel and interface science * acid-base equilibria * electrochemistry * biochemistry * confined synthesis The book gives readers not only an overview of nanocasting technology, but also sufficient information and knowledge for those wanting to prepare various nanostructured materials without needing to search the available literature.

Download or read book Metal Ceramic and Polymeric Composites for Various Uses written by John Cuppoletti and published by IntechOpen. This book was released on 2011-07-20 with total page 700 pages. Available in PDF, EPUB and Kindle. Book excerpt: Composite materials, often shortened to composites, are engineered or naturally occurring materials made from two or more constituent materials with significantly different physical or chemical properties which remain separate and distinct at the macroscopic or microscopic scale within the finished structure. The aim of this book is to provide comprehensive reference and text on composite materials and structures. This book will cover aspects of design, production, manufacturing, exploitation and maintenance of composite materials. The scope of the book covers scientific, technological and practical concepts concerning research, development and realization of composites.

Download or read book Ultrasound assisted Synthesis of Ordered Mesoporous Silica FDU 12 with a Hollow Structure1 written by and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Introduction to Zeolite Molecular Sieves written by Jiri Cejka and published by Elsevier. This book was released on 2007-10-02 with total page 1095 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introduction to Zeolite Molecular Sieves, 3rd Edition presents a collection of the most important results and ideas in the field of molecular sieve chemistry and technology, the most important experimental techniques related to the research activities in molecular sieves, and identifies new areas of molecular sieve chemistry. Chapters start at a reasonably simple entry level, but also covers the present state-of-the-art in the field. Topics covered include structure, synthesis, characterization, ion exchange, adsorption, diffusion, separations, and natural zeolites. * 6 years since the last edtion this book brings together the rapid development within the field of molecular sieve chemistry and applications * Accessible to newcomers to the field, also containing valuable information for experienced researchers * 27 chapters written by renowned scientists in their field, including updates on some 2nd edition chapters

Download or read book Synthesis Modification and Characterization of Ordered Mesoporous Silica Particles for Controlles Drug Release written by Shewaye Yismaw Wubetu and published by . This book was released on 2022 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Morphological Control of Multifunctionalized Mesoporous Silica Nanomaterials for Catalysis Applications written by Seong Huh and published by . This book was released on 2004 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: I found an efficient method to control the morphology of the organically monofunctionalized mesoporous silica materials by introducing different types of organoalkoxysilanes in a base-catalyzed co-condensation reaction. The monofunctionalized materials exhibit different particle morphologies relative to the pure MCM-41 material. The concentration dependence of the morphology is a critical factor to determine the final particle shape. A proposed mechanism of the shape evolution is also offered. After understanding the role of organoalkoxysilanes in producing various well-shaped nanomaterials, I also obtained a series of bifunctional mesoporous silica materials with certain particle morphology. A series of bifunctional mesoporous silica nanospheres (MSNs) whose physicochemical properties was investigated via solid state NMR techniques and Cu2 adsorption capacity tests. The ratio of two different organic groups inside of mesopores of these MSNs could be fine-tuned. These MSNs serve as a useful model system to study substrate selectivity in catalytic reactions and sorption phenomena. For example, the Cu2+ adsorption capacity of these materials was dictated by the chemical nature of the mesopores generated by the different organic functional groups. An investigation of the substrate selectivity of the bifunctionalized MSNs in a competitive nitroaldol reaction using an equimolar amount of two competing 4-nitrobenzaldehyde derivatives was performed. Shape-controlled bifunctional MSNs were employed as the catalysts. The properties of the MSNs were investigated using various spectroscopic methods and electron microscopy. The more hydrophobic the surface organic groups are, the higher the ratio of hydrophobic final product. This is the first example to demonstrate the selection of substrate using physicochemical nature of the mesopore surface other than the conventional shape selection in zeolite systems. I also created a cooperative dual catalyst system that is capable of activating two different substrates in aldol reaction, Henry reaction and cyanosilylation. One catalytic group activates the nucleophile, another organic group simultaneously activates the electrophile to enhance the total reaction rate. I systematically varied the amount of two organic groups and performed the three model reactions to compare rate enhancements.

Download or read book Mesoporous Silica templated Synthesis of Ordered Carbon Materials written by Nik Farah Hanim Kamarudin and published by . This book was released on 2012 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Basic Principles in Applied Catalysis written by Manfred Baerns and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by a team of internationally recognized experts, this book addresses the most important types of catalytic reactions and catalysts as used in industrial practice. Both applied aspects and the essential scientific principles are described. The main topics can be summarized as follows: heterogeneous, homogeneous and biocatalysis, catalyst preparation and characterization, catalytic reaction engineering and kinetics, catalyst deactivation and industrial perspective.

Download or read book Chemistry of Zeolites and Related Porous Materials written by Ruren Xu and published by John Wiley & Sons. This book was released on 2009-05-29 with total page 616 pages. Available in PDF, EPUB and Kindle. Book excerpt: Widely used in adsorption, catalysis and ion exchange, the family of molecular sieves such as zeolites has been greatly extended and many advances have recently been achieved in the field of molecular sieves synthesis and related porous materials. Chemistry of Zeolites and Related Porous Materials focuses on the synthetic and structural chemistry of the major types of molecular sieves. It offers a systematic introduction to and an in-depth discussion of microporous, mesoporous, and macroporous materials and also includes metal-organic frameworks. Provides focused coverage of the key aspects of molecular sieves Features two frontier subjects: molecular engineering and host-guest advanced materials Comprehensively covers both theory and application with particular emphasis on industrial uses This book is essential reading for researches in the chemical and materials industries and research institutions. The book is also indispensable for researches and engineers in R&D (for catalysis) divisions of companies in petroleum refining and the petrochemical and fine chemical industries.

Download or read book Characterization and Macroscale Morphology Control of Mesoporous Alumina Molecular Sieves written by Weihua Deng and published by . This book was released on 2001 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: Using a modified electrostatic templating approach, the mesoporous alumina with monolith morphology and hierarchical alumina particles with two characteristic pore scales were synthesized. The particles consisted of about 200 nm in diameter macropores in which the walls between the pores consisted of unimodal mesopores of several manometers in diameter. Some factors such as reaction temperature, the polarity of solvent and the concentration of surfactant/inorganic precursor assembly, which affect the macroscale morphology control, were investigated and discussed. Finally a possible mechanism for the morphology control was proposed.