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1

Li, Ruihua. "Devitrification behaviour of alkaline-earth silicate fibre." Thesis, Sheffield Hallam University, 1997. http://shura.shu.ac.uk/19960/.

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The alkaline-earth silicate fibres are a new generation of man-made insulation materials. The materials are amorphous on manufacture and have been shown to be soluble in physiological solutions and to be cleared from the lung in animal exposure trials. This reported study provides a thorough investigations of the devitrification behaviour of Superwool X-607 (Morgan Materials Technology), and two further compositions, code names A2 and B3.Thermal exposures were made within the region extending from 700 to 1250°C and 10 minutes to 3240 hours in clean furnace environments. The devitrified microstructures and products were identified using X-ray powder diffraction and analytical electron microscopy. Details are provided of the development of specimen preparation techniques to enable fibre cross-sections to be analyzed in the TEM.The devitrification products are presented as a function of exposure temperature and time for all 3 compositions. The amorphous glass separated into a silica-rich phase and an alkaline-earth silicate rich phase and the development of these amorphous phases is presented and discussed. The subsequent devitrification of these separated phases into associated silica crystalline phases and alkaline-earth silicate crystalline phases, and, in each case, the subsequent phases and transformations with increasing thermal exposure are also presented and discussed. For the crystalline silica phases, the following unusual transformation situation was identified in all 3 compositions: amorphous silica → alpha-quartz → alpha-cristobalite → tridymite. In comparison with established understanding of silica phase transformations, the following anomalies were identified and explained: a) the formation of quartz as the primary crystalline silica phase at temperatures ≥1000°C, and b) the subsequent formation of alpha-cristobalite, the low-temperature form, other than B-cristobalite, the high-temperature form, which was the only silica phase identified in the devitrified aluminosilicate fibres. For the alkaline-earth silicate phases, two forms of wollastonite solid solution were characterised. The low-temperature form, containing more Mg[2+], transforms to the high-temperature form and diopside at temperatures above 900°C. The low-temperature anomaly, ie the formation of the immature high-temperature form below 900°C is possibly due to a secondary phase separation. Pseudowollastonite was found to be metastable in the investigated temperature region. It is suggested that the detailed transformation process among these alkaline-earth silicate phases has been identified for the first time. This thesis also includes a detailed review of published studies concerning this materials systems as well as recommendations for further work.
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2

Kaylor, Rosann Matthews. "The high-temperature, alkaline degradation of a new cellulose model compound." Thesis, Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/27286.

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3

Pavasars, Ivars. "Characterisation of organic substances in waste materials under alkaline conditions /." Linköping : Tema, Univ, 1999. http://www.bibl.liu.se/liupubl/disp/disp99/arts196s.htm.

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4

Nesvaderani, Farhang. "Modification of MnO₂-based cathode materials for rechargeable alkaline batteries." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/62860.

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5

Bradwell, David (David Johnathon). "Liquid metal batteries : ambipolar electrolysis and alkaline earth electroalloying cells." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/62741.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2011.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 198-206).<br>Three novel forms of liquid metal batteries were conceived, studied, and operated, and their suitability for grid-scale energy storage applications was evaluated. A ZnlITe ambipolar electrolysis cell comprising ZnTe dissolved in molten ZnCl 2 at 500 0C was first investigated by two- and three-electrode electrochemical analysis techniques. The electrochemical behavior of the melt, thermodynamic properties, and kinetic properties were evaluated. A single cell battery was constructed, demonstrating for the first time the simultaneous extraction of two different liquid metals onto electrodes of opposite polarity. Although a low open circuit voltage and high material costs make this approach unsuitable for the intended application, it was found that this electrochemical phenomenon could be utilized in a new recycling process for bimetallic semiconductors. A second type of liquid metal battery was investigated that utilized the potential difference generated by metal alloys of different compositions. MgjlSb cells of this nature were operated at 700 °C, demonstrating that liquid Sb can serve as a positive electrode. Ca,MgIIBi cells also of this nature were studied and a Ca,Mg liquid alloy was successfully used as the negative electrode, permitting the use of Ca as the electroactive species. Thermodynamic and battery performance results suggest that Ca,MgIISb cells have the potential to achieve a sufficient cell voltage, utilize earth abundant materials, and meet the demanding cost and cycle-life requirements for use in grid-scale energy storage applications.<br>by David J. Bradwell.<br>Ph.D.
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6

Bidault, Fabrice. "Development of alkaline fuel cell gas diffusion cathodes using new substrate materials." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/5663.

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Hydrogen, as a clean and renewable fuel, may play a key role in the near future because of the increasing cost of fossil fuels and the impact of CO2 on the climate. Fuel cells are electrochemical devices which directly convert chemical energy stored in hydrogen into electrical energy at high efficiency with only water and heat as byproducts. A leading candidate fuel cell technology for operation on hydrogen fuels is the proton exchange membrane fuel cell (PEMFC). But today its commercialization remains limited, mainly because of the price of the materials used for electrode manufacture. Catalysts based on precious metals such as platinum, which are currently inherent to PEMFCs, preclude inexpensive mass production. In contrast an alternate fuel cell technology well suited to hydrogen fuels, the alkaline fuel cell (AFC), offers the potential for low cost, mass producible fuel cells, without the need for platinum based catalysts, but has received less attention in recent years. The aim of this work is to develop AFC gas diffusion cathodes using new substrate materials (nickel foam and porous silver membranes) which ally mechanical support, current collection and catalyst support so as to reduce the cost of the electrode. Silver, which is one of the most active materials for the oxygen reduction reaction (ORR) and which is 100 times cheaper than platinum, has been used as the catalyst in this work. The effect of optimising the cathode performance has been monitored using DC polarization curves and electrochemical impedance spectroscopy. Both the nickel foam and porous silver membrane substrates have been successfully developed as the gas diffusion medium in aqueous alkaline media. Silver plated nickel foam showed a decrease in both the Ohmic and charge transfer resistance compared to uncoated nickel foam, leading to improved performance. The porous silver membrane showed good performance in a passive air-breathing cell (50 mW cm-2 at 25 oC) due to its high surface area and optimised hydrophobic properties.
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7

Molina, García Miguel Ángel. "Graphene-derived materials as oxygen reduction catalysts in alkaline conditions for energy applications." Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8871/.

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Graphene is a relatively new carbon material increasingly finding technological applications due to its unique physical and engineering properties. Here, its application as catalyst for the oxygen reduction reaction (ORR) in alkaline media is investigated. First, the role of graphene-related materials (including multi-walled carbon nanotubes) as catalyst supports is compared to the widely used carbon black, finding that the ORR follows a mixed behaviour between the direct 4-electron pathway and the indirect 2-step mechanism on graphene-supported platinum catalysts. Further, different combinations of boron, nitrogen, phosphorus and sulphur metal-free doped-graphene catalysts have been systematically synthesised and evaluated, finding that dual-doped graphene catalysts yield the best ORR performance. Specifically, phosphorus and nitrogen dual-doped graphene (PN-Gr) demonstrates the highest catalytic activity, with 3.5 electrons transferred during the ORR. Doped-graphene/perovskite oxide hybrid catalysts have been also tested, yielding PN-Gr/La0.8Sr0.2MnO3 the best ORR activity in terms of measured current density, achieving a value that is 85% of that reported for a commercial Pt/C catalyst. Moreover, SN-Gr/La0.8Sr0.2MnO3 produces the lowest amount of peroxide formation with only 10%. These results confirm the graphene-derived catalysts as promising alternatives to the current platinum-based catalysts, and could enable the important issues related to its practical application to be overcome.
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8

Quader, M. M. A. "Improvement of the alkaline delignification of wood and nonwood raw materials for pulp production /." Åbo : Åbo akademi university, 2003. http://catalogue.bnf.fr/ark:/12148/cb40116564x.

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9

O'Brien, Anna Yosick. "Advances in the design of heavy alkaline earth metal complexes as precursors for chemical vapor deposition." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2005. http://wwwlib.umi.com/cr/syr/main.

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10

Yin, Zhewen. "Non-precious Metal Catalysts for Oxygen Reduction Reaction in Alkaline Solutions." Scholar Commons, 2018. http://scholarcommons.usf.edu/etd/7250.

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Mesoporous WO3 powders were prepared via sol-gel processing synthesis using nonionic surfactant Pluronic (P-123) as the template. The influences of heating temperature on the pore structure and properties of WO3 powders were investigated. Three kinds of modifications were compared and evaluated after finding out the best heating condition. Different amount of lanthanum was doped into mesoporous WO3 to improve its Oxygen Reduction Reaction (ORR) activity. Several factors contributing to the increase of catalytic performance were discussed. Vulcan carbon powder was also used as a support to increase the catalysts’ electrical conductivity as well as dispersity. The component, microstructure and specific surface area of samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and N2 adsorption-desorption analysis. A three-electrode system with a rotating disk electrode (RDE) was used to detect samples’ electrochemical performance towards ORR in alkaline solutions. The as-prepared mesoporous La/WO3 powder with a ratio of La: W = 1: 10, calcined at 550℃ and supported by 25 wt% Vulcan carbon powder, exhibited highest ORR catalytic activity.
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11

Teng, Weijie Ruhlandt-Senge Karin. "From polymerization initiators to precursors for solid-state materials syntheses and structures of a series of molecular alkali and alkaline earth metal derivatives /." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2004. http://wwwlib.umi.com/cr/syr/main.

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12

Siong, Victor [Verfasser]. "Research and optimizations of iron composites as negative electrode materials for aqueous alkaline batteries / Victor Siong." Ulm : Universität Ulm, 2019. http://d-nb.info/1183099711/34.

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13

Ravindran, Naveenkamal. "Durability of E-glass fiber reinforced vinyl ester polymer composites with nanoclay in an alkaline environment." Morgantown, W. Va. : [West Virginia University Libraries], 2005. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4209.

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Thesis (M.S.)--West Virginia University, 2005.<br>Title from document title page. Document formatted into pages; contains vii, 54 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 51-52).
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14

Ren, Yufu. "Microwave Assisted Synthesis of Alkaline Earth Phosphate Coating and its Applications for Biomedical Implants." University of Toledo / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1513204146096617.

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15

Zhang, Zhihao. "The Development of Three Dimensional Porous Nickel Materials and their Catalytic Performance towards Oxygen Evolution Reaction in Alkaline Media." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/40636.

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As the global energy crisis and environmental pollution problem continues, there is an increasing demand for clean and sustainable energy storage and conversion technologies, such as water-splitting electrolysis. Water electrolysis is a process of running an electrical current through water in separating the hydrogen and oxygen. Oxygen evolution reaction (OER) is a key reaction in this electrochemical process, and the electrochemical performance of these systems is usually hindered by the slow OER reaction kinetics. In order to achieve high energy conversion efficiency, the development of efficient OER catalysts is the key. To achieve that, abundant research is done by using noble metal oxides as catalyst, such as IrO2 and RuO2. However, considering their high cost, a cheap earth-abundant material with a high OER catalytic activity is required. Accordingly, this study has been focused on the synthesis of three dimensional porous structured Ni-based OER catalysts. First, a 3D porous Ni meso-foam was developed through a facile high-temperature one-pot synthesis method, and its catalytic activity towards OER was explored. Specifically, the as-synthesized Ni meso-foam material, referred to as raw NMF, has a wire-linked structure and high surface area. A reduction procedure was introduced to obtain reduced Ni meso-foam materials, referred to as NMF-H2. It was also oxidized in air at 600 ℃ to form a semi-hollow NiO crosslinking phase and subsequently reduced in H2 at 300℃, forming a regenerated porous Ni foam material, referred to as NMF-O2/H2. The composition and morphology of all materials were investigated by XRD and SEM, respectively. The SEM image reveals that, in the porous NMF-O2/H2, the cross-linked meso-wire structure was maintained, and the average pore size is between 0.5-5 μm. Electrochemical analysis show that the OER activity of the Ni foam catalysts follows NMF-O2/H2 > NMF-H2 > raw NMF. In addition to the NMF-based materials, a Ni/Ni(OH)2 layer-structured electrocatalyst, referred to as NiDHBT, was also developed using a dynamic hydrogen bubble templating (DHBT) method. First, the 3D-porous micro Ni/Zn nanoplatelets were constructed in a two-step DHBT deposition method. The Ni/Zn foil was used as a scaffold, featured with the open porous structure and high surface area, for the subsequent electrodeposition of Ni(OH)2. Then, the Zn was etched from the as-prepared Ni/Zn/Ni(OH)2 nanocomposite to obtain the NiDHBT. The catalytic performance of the NiDHBT toward OER reaction was evaluated, and the optimal catalysts developed from different electro deposition potentials were determined. On the recognition of the high catalytic activity of NMF-O2/H2 and NiDHBT, porous structured FeOx-Nickel meso-foam, referred to as Fe@NMF-O2/H2, and FeOx- Ni/Ni(OH)2 layered-structure materials, referred to as Fe@NiDHBT, was further developed to explore the benefits of FeOx deposition for its OER catalytic performance. The deposition of FeOx is achieved by physical mixing FeOx colloid with NMF-O2/H2 and NiDHBT, and the electrochemical performance of these materials was examined in 1 M KOH. Among the developed materials, the best performing catalyst is Fe@NiDHBT synthesized by loading FeOx colloid onto the NiDHBT support. The overpotential for Fe@NiDHBT to reach 10 mA·cm-2 is 247mV, and the corresponding Tafel slope is 48.10mV·dec-1. Therefore, it was concluded that the FeOx¬¬ loading modification is an effective strategy to improve the OER activity of Ni foam-based catalysts.
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16

Blasco, Ahicart Marta. "Earth Abundant Materials for Electrocatalytic Water Oxidation: Enhancing Efficiency and Robust Performance in Acidic, Neutral and Alkaline Media." Doctoral thesis, Universitat Rovira i Virgili, 2017. http://hdl.handle.net/10803/457706.

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En aquesta tesi doctoral presentem diferents estratègies per al desenvolupament d’elèctrodes, basats en elements abundants en l’escorça terrestre, actius en l’oxidació electrocatalítica de l’aigua en diferents medis. En primer lloc, hem precipitat el clúster [Co9(H2O)6(OH)3(HPO4)2(PW9O34)3]16− (Co9) amb Ba2+ i Cs+ per obtindre sals insolubles en aigua que poden ser mesclades amb una matriu conductora, com la pasta de carboni. Els elèctrodes de BaCo9 presenten una activitat excel·lent en medi àcid, combinada amb 100% d’eficiència Faradàica i estabilitat a llarg termini. En segon lloc, el clúster nonanuclear Co9 també ha estat combinat amb un polímer conductor (polipirrol) per obtenir elèctrodes híbrids orgànic-inorgànics actius en l’oxidació electrocatalítica de l’aigua en medi neutre. Aquest mètode de processament és molt interessant, ja que proporciona elèctrodes versàtils a partir de materials barats i abundants. Finalment, hem analitzat òxids binaris i ternaris amb diferent composició (Ni, Zn, Fe i Cr) per millorar l’activitat dels òxids metàl·lics front l’oxidació catalítica d’aigua en medi bàsic. Aquells compostos amb fase espinela i -Fe2O3 hematita presenten elevada eficiència combinada amb bona estabilitat a llarg termini.<br>En la presente tesis doctoral presentamos diferentes estrategias para desarrollar electrodos, basados en elementos abundantes en la corteza terrestre, activos en la oxidación electrocatalítica del agua en diferentes medios. En primer lugar, hemos precipitado el clúster [Co9(H2O)6(OH)3(HPO4)2(PW9O34)3]16− (Co9) con Ba2+ i Cs+ para obtener sales insolubles en agua que pueden ser mezcladas con una matriz conductora, como la pasta de carbono. Los electrodos de BaCo9 presentan una actividad excelente en medio ácido, combinada con 100% de eficiencia Faradaica y estabilidad a largo plazo. En segundo lugar, el clúster nonanuclear Co9 también ha sido combinado con un polímero conductor (polipirrol) para obtener electrodos híbridos orgánico-inorgánicos activos en la oxidación electrocataítica del agua en medio neutro. Este método de procesamiento es muy interesante, ya que proporciona electrodos versátiles a partir de materiales baratos y abundantes. Finalmente, hemos analizado óxidos binarios y ternarios con diferente composición (Ni, Zn, Fe i Cr) para mejorar la actividad de los óxidos metálicos frente a la oxidación electrocatalítica del agua en medio básico. Los compuestos con fase espinela y -Fe2O3 hematita presentan elevada eficiencia combinada con buena estabilidad a largo plazo.<br>In this Doctoral Thesis, different approaches to develop suitable working anodes based on Earth abundant metals for the electrocatalytic water oxidation reaction in different media have been presented. We have precipitated the nonanuclear cobalt cluster [Co9(H2O)6(OH)3(HPO4)2(PW9O34)3]16− (Co9) with Ba2+ and Cs+ to obtain water-insoluble salts that can be blended with a solid-state matrix, such as carbon paste. The BaCo9 have shown excellent and unparalleled performance for the electrocatalytic water oxidation in acidic media, yielding 100% Faradaic efficiency matched with good long-term stability. We have also incorporated the homogeneous Co9 POM into a conducting polymer matrix (i. e. polypyrrole) to obtain organic-inorganic anodes active in electrocatalytic water oxidation reaction in neutral conditions. This interesting processing approach has yielded versatile electrodes obtained from low cost and available raw materials. Finally, we have screened binary and ternary mixed oxide compositions, based on Ni, Zn, Fe and Cr, for the enhancement of electrocatalytic water oxidation in alkaline media. Cubic spinel phases, as well as, -Fe2O3 hematite have shown best efficiency combined with good long-term stability under working conditions.
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17

Flídrová, Michaela. "Studium účinnosti plastifikačních přísad v souvislosti s povrchovou chemií systému alkalicky aktivované strusky." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2021. http://www.nusl.cz/ntk/nusl-444210.

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Alkali-activated materials (AAM) are construction materials with great potential, especially for their environmental friendliness, but also due to their mechanical properties. Therefore, it is appropriate to pay further attention to these binders. This diploma thesis deals with monitoring the effectiveness of plasticizers in connection with the surface chemistry of the alkali-activated slag system. Sodium hydroxide and sodium water glass were used as alkaline activators for the preparation of alkali-activated blast furnace slag-based systems. To study the effectiveness of the lignosulfonate plasticizer, yield stress, heat flow, adsorption and zeta potential were monitored depending on the amount and time that the plasticizer was added to the system. The results show that the type of activator used in the mixtures plays an important role. NaOH-activated samples revealed the best efficiency of lignosulfonate plasticizers. A key factor in studying the behavior of the studied mixtures was the measurement of the zeta potential, which provided insight into the surface charge of blast furnace slag particles related to the ability of lignosulfonate to adsorb on grains of alkali-activated slag.
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18

Langová, Markéta. "Účinek plastifikátorů na chování a vlastnosti alkalicky aktivovaných materiálů." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2017. http://www.nusl.cz/ntk/nusl-316430.

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Alkali activated materials could be suitable alternative to construction materials based on ordinary Portland cement (OPC). Therefore, it is advisable to pursue these binders further on. Aim of this thesis is to clarify the effect of lignosulfonate-based plasticizer and polycarboxylate-based superplasticizer on the behaviour and nature of alkali activated materials. For the purposes of studying the efficiency of plasticizing additives, the change of workability of alkali activated blast furnace slag in dependence on time, effect of additives on mechanical properties as well as, with usage of isothermal calorimetry, their impact on kinetics of solidification and hardening had been observed. The stability of the plasticizing admixtures in a high alkaline environment such as water glass and sodium hydroxide had been studied using infrared spectrometry. As a last step, X-ray photoelectron spectroscopy (XPS) had been used while clarifying the chemical changes in the structure of plasticizing additives after adsorption to blast furnace slag.
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19

Hall, David Scott. "An Electrochemical and Spectroscopic Investigation of Nickel Electrodes in Alkaline Media for Applications in Electro-Catalysis." Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31627.

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Nickel-based catalysts in aqueous alkaline media are low-cost electrode materials for electrolytic hydrogen generation, a renewable method of producing fuel and industrial feedstock. However, further work is necessary to develop inexpensive electro-catalyst materials with high activity and long-term stability. This thesis employs spectroscopic and electrochemical methods to directly address specific research problems for the development of improved materials and devices with commercial or industrial value. The first chapter reviews the applications of nickel electrodes; the structures of nickel, nickel hydroxides, and nickel hydrides; and techniques for measuring the electrochemically active surface area (AECSA) of nickel. In the second chapter, electrochemically precipitated nickel hydroxide materials are fully characterized by Raman spectroscopy, Fourier-transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). This work unifies and simplifies the large body of literature on the topic by considering two fundamental phases, α- and β-Ni(OH)2, and various types and extents of structural disorder. The third chapter examines and demonstrates the potential applications of in situ Raman spectroscopy by monitoring the spontaneous ageing of α-Ni(OH)2 to β-Ni(OH)2 in pure water at room temperature. The fourth chapter considers the longstanding problem of electrode deactivation, the gradual decrease in nickel electro-catalyst activity during prolonged hydrogen production. Voltammetric and XRD evidence demonstrates that hydrogen atoms can incorporate into the electrode material and cause structural disorder or the formation of α-NiHx and β-NiHx at the surface. The voltammetric formation of NiOx, α-Ni(OH)2, β-Ni(OH)2, and β-NiOOH surface species are examined by electrochemical and XPS measurements. The fifth chapter of this thesis presents a new method to measure the AECSA by adsorption of oxalate to the (001) surface of the surface Ni(OH)2, as evidenced by voltammetric and attenuated total reflectance (ATR) FT-IR spectroscopy measurements. The adsorbed oxalate limits the surface hydroxide to a single layer. The surface NiOOH/Ni(OH)2 reduction peak during the reverse scan may be used to accurately and precisely measure the AECSA. The error of this method is estimated at < 10 %.
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Björquist, Stina. "Separation for regeneration : Chemical recycling of cotton and polyester textiles." Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-12388.

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In 2015, 96.7 million tonnes of textile fibres were produced world-wide. Our high consumption of textiles leads to an increased amount of textile waste. In Sweden, the majority of used clothing and textiles are incinerated due to the lack of recycling techniques. A large amount of post-consumer textile waste is made from blended materials. One of the most common blends, used in as near as all workwear and service textiles, is cotton/polyester. To enable chemical recycling of such textiles, cotton and polyester must first be separated. The aim of this thesis was to separate the materials by depolymerizing the polyester using alkaline hydrolysis. The focus of the work was on how such a process should be performed without a catalyst, in order to result in both a high yield and a high purity of the cotton residue. In order to recycle the residue as a raw material for manufacturing of man-made cellulosic fibres, the cellulose chains in the cotton must also be maintained as unaffected as possible. The polyester in new sheets was completely depolymerized after 390 min at a temperature of 90ºC using a 10% sodium hydroxide concentration and a 1% material-to-liquor concentration. The separation using these conditions gave high yields (above 96%) of the cotton residue regardless of the material fineness used in the process. Furthermore, the separation performed on old sheets show that a pure cotton residue could be produced using higher material concentrations. It was shown that the cotton residue from old sheets, laundered around 50 times, had an intrinsic viscosity comparable to dissolving pulps used for viscose fibre spinning. This study concludes that alkaline hydrolysis without the use of a catalyst could be used to separate cotton and polyester in blended textiles. Furthermore, the findings show that cotton percentage in old sheets only decreased slightly after 50 launderings. Characterization of the materials using ATR FTIR spectroscopy indicate that an integrated textile recycling of hospital bed sheets could be performed since the sheets only contain cotton and polyester in all parts of the sheets.
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Renman, Agnieszka. "On-site wastewater treatment : Polonite and other filter materials for removal of metals, nitrogen and phosphorus." Doctoral thesis, KTH, Mark- och vattenteknik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4811.

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Bed filters using reactive materials are an emerging technology for on-site wastewater treatment. Chemical reactions transfer contaminants from the aqueous to the solid phase. Phosphorus is removed from domestic wastewater by sorption to filter materials, which can then be recycled to agriculture as fertilisers and soil amendments. This thesis presents long-term column and field-scale studies of nine filter materials, particularly the novel product Polonite®. Phosphorus, nitro-gen and metals were removed by the mineral-based materials to varying degrees. Polonite and Nordkalk Filtra P demonstrated the largest phosphorus removal capacity, maintaining a PO4-P removal efficiency of &gt;95%. Analysis of filter bed layers in columns with downward wastewater flow, showed that phosphorus, carbon and nitrogen content was vertically distributed, with de-creasing values from surface to base layer. Polonite and Filtra P accumulated 1.9-19 g P kg-1. Nitrogen in wastewater was scarcely removed by the alkaline filter materials, but transformation from NH4-N to NO3-N was &gt;90%. Pot experiments with barley (Hordeum vulgare L.) revealed that after wastewater treatment, slags and Polonite could increase plant production. Batch experi-ments and ATR-FTIR investigations indicated that amorphous tricalcium phosphate (ATCP) was formed in the materials, so some of the accumulated PO4-P was readily available to plants. Low heavy metal contents occurred in the materials, showing that they can be applied as soil amend-ments in agriculture without contamination risks. A full-scale treatment system using Polonite as filter material showed an average PO4-P removal efficiency of 89% for a 92-week period, indicat-ing the robustness of the filter bed technology.<br>QC 20100907
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22

Eiblmeier, Josef [Verfasser], and Werner [Akademischer Betreuer] Kunz. "pH coupled co-precipitation of alkaline-earth carbonates and silica - complex materials from simple chemistry / Josef Eiblmeier. Betreuer: Werner Kunz." Regensburg : Universitätsbibliothek Regensburg, 2013. http://d-nb.info/1034758667/34.

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23

Rios, Reyes Carlos A. "Synthesis of zeolites from geological materials and industrial wastes for potential application in environmental problems." Thesis, University of Wolverhampton, 2008. http://hdl.handle.net/2436/39855.

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Zeolites are among the least-known products for environmental pollution control, separation science and technology. Due to their unique porous properties, they are used in various applications in petrochemical cracking, ion-exchange and separation and removal of gases and solvents. The preparation of synthetic zeolites from chemical reagents is expensive. Therefore, in order to reduce costs, zeolite researchers are seeking cheaper aluminosilicate bearing raw materials, such as clay minerals, to produce synthetic zeolites. This research concerns the synthesis of zeolites and zeotypes derived from low-cost materials like kaolinite (KAO), natural clinker (NC) and fly ash (FA). The motivation for using these sources as the starting materials in zeolite synthesis is driven by factors, such as they are cheap and available in bulk quantities, are currently under-utilized, have high workability, and require less water (or solution) for activation. The raw materials were activated by two different routes: (1) classic alkaline hydrothermal synthesis and (2) alkaline fusion prior to hydrothermal synthesis. In the first method, the synthesis of zeolitic materials was carried out generally in alkaline media, although KAO or its calcination product, metakaolinite (MTK), was also activated in the presence or absence of structure directing agents (SDAs) and additional silica (precipitated SiO2), with the last one determining the SiO2/Al2O3 ratio of the reaction mixture and the time given for zeolitization. Synthesis in fluoride- and calcium-bearing media was also used to activate kaolinite. The process of synthesis was optimized by applying a wide range of experimental conditions with a wide range of reaction temperature, time, mineralizer concentration and solid/solution ratio. In the second approach, an alkaline fusion step was conducted prior to hydrothermal treatment, because it plays an important role in enhancing the hydrothermal conditions for zeolite synthesis. On the other hand, this approach was adopted because it can dissolve more aluminosilicates. The main synthesis products obtained after activation of KAO in NaOH solutions included zeolite LTA (LTA), sodalite (SOD), cancrinite (CAN), faujasite (FAU), zeolite Na-P1 (GIS), JBW-type zeolite (JBW), analcime (ANA), whereas the activation of KAO in KOH solutions produced chabazite (CHA), zeolite Barrer-KF, phillipsite (PHI) and K-feldspar. The hydrothermal conversion of kaolinite in fluoride media did not produce successful results, although traces of FAU, GIS, CHA, SOD and CAN crystallized. The activation of KAO in the system CaO-SiO2-Al2O3-H2O promoted the formation of different calcium silicate hydrate (C-S-H) phases, including hydrogarnet (HYD) and tobermorite (TOB). Following the fusion approach, the main zeolitic phases obtained using NaOH as mineralizer were LTA and CAN. The main as-synthesized zeolites obtained from NC by the conventional hydrothermal treatment method include PHI, SOD and CAN. Using the fusion approach, FAU and LTA were obtained with NaOH as an activator, whereas non-zeolitic material crystallized when KOH was used. The main as-synthesized zeolitic materials obtained by hydrothermal reaction of FA include PHI, zeolite Barrer-KF, CHA and SOD with traces of TOB, ANA, zeolite LTF (LTF) and herschelite (HER), appearing occasionally. By the fusion approach, FAU was obtained with NaOH as activator, whereas no zeolitic material crystallized using KOH. Experimental results indicate that the method, mineralizer, concentration and time have strong effects on the type and degree of crystallinity of the synthesis products. On the other hand, the type and chemical composition of the as-synthesized products are strongly dependent on the chemical composition of the starting material. The chemistry of zeolite synthesis was subject to perturbations caused by the presence of impurities in the raw materials, which may remain insoluble during crystallization and cause undesired species to nucleate, developing mixtures of different types of zeolites. However, other physicochemical factors may play a very important role in the thermodynamics and kinetics of zeolite formation. The raw materials have very high contents of SiO2 and Al2O3, with SiO2/Al2O3 ratios appropriate for the synthesis of low-Si zeolitic materials with high crystallinity and cation exchange capacity (CEC). However, although zeolites’ CEC represents a very important characteristic quality in the removal of undesired species from polluted effluents, it is not the deciding factor in determining zeolite performance during ion exchange processes, since numerous other factors also need to be considered. Finally, the potential application of the raw materials and their as-synthesized products as low-cost sorbents in the remediation of metal ions and ammonium from wastewater effluents was investigated. PHI showed a lower efficiency than FAU. Selectivity of FAU for metal removal was, in decreasing order, Fe>As>Pb>Zn>Cu>Ni>Cr. Based on these results, the use of these materials has the potential to provide improved methods for the treatment of contaminated effluents.
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24

Nunes, Andreia. "Hybrid mesoporous materials for the oxidative depolymerization of lignin into valuable molecules." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1024.

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La lignine est un des polymères naturels les plus abondants et le seul constituant de la biomasse basé sur des unités aromatiques et, à ce titre, représente une ressource renouvelable prometteuse pour la production durable de molécules organiques plus complexes. Les travaux de cette thèse portent sur le développement de matériaux catalytiques capables de transformer sélectivement la lignine en molécules fonctionnelles de base, hautement oxygénées, et l'étude de leur mise en oeuvre en condition alcaline oxydante en utilisant le peroxyde d'hydrogène comme donneur d'oxygène. Différentes familles de matériaux hybrides de type SBA-15 à base de titane, Au/titane, Ag/titane et Fe(TAML) ont tout d'abord été synthétisées et entièrement caractérisées. Des études catalytiques comparatives ont ensuite été réalisées afin d'évaluer leurs performances en termes de degré de dépolymérisation et distribution de produits. Le catalyseur présentant le plus fort potentiel, le matériau TiO2 supporté sur SBA-15, a ensuite été soumis à des études de réactivité plus poussées afin d'optimiser les différents paramètres réactionnels (température, temps de réaction et quantité d'oxydant) permettant d'atteindre en présence d'un excès d'oxydant jusqu'à 90 %pds de conversion de la lignine et à 80°C un rendement en bio-huile de 50%pds constituée principalement d'acides carboxyliques et molécules aromatiques potentiellement valorisables<br>Lignin is one of the most abundant natural polymers and the only biomass constituent based on aromatic units and as such represents a promising renewable resource for the sustainable production of complex organic molecules. This dissertation reports on the development of catalytic materials capable of selectively transform lignin into basic functional molecules with high oxygen content and the study of their performance under alkaline oxidative conditions, using hydrogen peroxide as oxygen donner. Different families of hybrid materials based on the SBA-15 scaffold were first synthesized by incorporation of titanium, Au/titanium, Ag/titanium and Fe-TAML and completely characterized. Comparative catalytic studies were then accomplished in order to evaluate their performance in terms of degree of depolymerization and product distribution. The catalyst with the highest potential, the TiO2 based SBA-15 material, was then submitted to further reactivity studies in order to optimize the different reaction parameters (temperature, reaction time and quantity of oxidant). In the presence of an excess of oxidant, conversions up to 90 wt. % were obtained, whereas a temperature of 80 °C allowed to obtain a yield in bio-oil of 50 wt. %, which is mainly composed of carboxylic acids and aromatic molecules with potential to be further valorized
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25

Nookala, RamaKrishna. "Mechanistic Study of Silane Assisted Rubber to Brass Bonding and the Effect of Alkaline Pre Treatment of Aluminum 2024 T3 on Silane Performance." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1148065049.

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26

Matsukata, Masahiko. "Study of catalytic gasification of hydrocarbons and carbonaceous materials on alkali and alkaline earth compounds = Arukari oyobi arukari dorui kinzoku kagōbutsu o shokubai to suru tanka suisorui oyobi tansoshitsu busshitsu no sesshoku gasu-ka ni kansuru kenkyū /." Electronic version of summary, 1989. http://www.wul.waseda.ac.jp/gakui/gaiyo/1493.pdf.

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27

Srepusharawoot, Pornjuk. "Computational Studies of Hydrogen Storage Materials : Physisorbed and Chemisorbed Systems." Doctoral thesis, Uppsala universitet, Materialteori, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-132875.

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This thesis deals with first-principles calculations based on density functional theory to investigate hydrogen storage related properties in various high-surface area materials and the ground state crystal structures in alkaline earth dicarbide systems. High-surface area materials have been shown to be very promising for hydrogen storage applications owing to them containing numerous hydrogen adsorption sites and good kinetics for adsorption/desorption. However, one disadvantage of these materials is their very weak interaction with adsorbed hydrogen molecules. Hence, for any feasible applications, the hydrogen interaction energy of these materials must be enhanced.  In metal organic frameworks, approaches for improving the hydrogen interaction energy are opening the metal oxide cluster and decorating hydrogen attracting metals, e.g. Li, at the adsorption sites of the host.  In covalent organic framework-1, the effects of the H2-H2 interaction are also found to play a significant role for enhancing the hydrogen adsorption energy. Moreover, ab initio molecular dynamics simulations reveal that hydrogen molecules can be trapped in the host material due to the blockage from adjacent adsorbed hydrogen molecules. In light metal hydride systems, hydrogen ions play two different roles, namely they can behave as "promoter" and "inhibitor" of Li diffusion in lithium imide and lithium amide, respectively.  By studying thermodynamics of Li+ and proton diffusions in the mixture between lithium amide and lithium hydride, it was found that Li+ and proton diffusions inside lithium amide are more favorable than those between lithium amide and lithium hydride. Finally, our results show that the ground state configuration of BeC2 and MgC2 consists of five-membered carbon rings connected through a carbon atom forming an infinitely repeated chain surrounded by Be/Mg ions, whereas the stable crystal structure of the CaC2, SrC2 and BaC2 is the chain type structure, commonly found in the alkaline earth dicarbide systems.<br>Felaktigt tryckt som Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 712
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28

Huang, Bowen. "Computational materials discovery : prediction of carbon dioxide and nitrogen-based compounds under pressure using density functional theory and evolutionary algorithm." Thesis, Poitiers, 2017. http://www.theses.fr/2017POIT2301/document.

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La découverte de nouveaux composés cristallins par simulation numérique est un défi majeur en Science des Matériaux. Aussi, trois familles sont à l'étude : les composés constitués de lithium et de dioxyde de carbone ; les phases nitrures MxNy avec M = Mg, Ba, Mo et Zr ; les systèmes GaPO4 et SiS2. Les structures cristallographiques sont déterminées in silico à l'aide de l'algorithme évolutionnaire USPEX couplé à des calculs DFT (VASP). L'étude du polymorphisme en fonction de la pression est conduite tandis que l'analyse des propriétés structurales et électroniques constitue le cœur de cette thèse. Nos travaux mettent clairement en évidence l'effet de la pression dans l'émergence de stoichiométries inhabituelles telles que Li2(CO2), MgN4, et BaN10. Certains de ces matériaux hypothétiques restent stables à pression atmosphérique. Il est montré que l'ajout d'un élément du bloc s autorise la « polymérisation » des molécules insaturées CO2 et N2 à des pressions plus basses. Ainsi, l'oxalate C2O42- polymérise en chaine infinie poly-dioxane à 33 GPa dans LiCO2 ; la nouvelle composition Li2CO2 présente des motifs de type éthène (-O)2C=C(O-)2 ; des chaînons N2, N3 et N4, des anions pentazolates N5- et des cycles N6 sont identifiés dans les phases AexNy, ainsi que des chaines covalentes infinies (1D) stabilisés par les cations alcalino-terreux Ae ; le composé Ba3N2 est un électride conducteur à pression ambiante et un isolant au-dessus de 5 GPa ; la structure stable de MoN2 a des entités N2 encapsulées, et non l'arrangement en feuillet de type MoS2 proposé par des expérimentateurs ; nos prédictions couplées aux données DRX permettent l'élucidation de la structure de GaPO4 à 20 GPa<br>The discovery of novel crystalline compounds by numerical simulation is a major challenge in Materials Science. Also, three families are being studied: compounds consisting of lithium and carbon dioxide; the MxNy nitride phases with M = Mg, Ba, Mo and Zr; the GaPO4 and SiS2 systems. The crystallographic structures are determined in silico using the evolutionary algorithm USPEX coupled with DFT calculations (VASP). The study of polymorphism as a function of pressure is carried out whereas the analysis of structural and electronic properties constitutes the heart of this thesis. Our work clearly presents the effect of pressure on the emergence of unexpected stoichiometries, such as Li2(CO2), MgN4, and BaN10. Some of these hypothetical materials remain stable at atmospheric pressure. It's shown that the addition of the s-block element allows the "polymerization" of the unsaturated molecules CO2 and N2 to be carried out at lower pressures. Thus, oxalate C2O42- polymerizes in an infinite poly-dioxane chain in LiCO2 at 33 GPa; the new Li2CO2 composition presents the ethene like (-O)2C=C(O-)2 motif; N2, N3 and N4 finite chains, N5-pentazolate anions, and N6 rings are identified in the AexNy phases, as well as, infinite covalent (1D) chains stabilized by the alkaline earth cations (Ae); the Ba3N2 compound is a conductive electride at ambient pressure and an insulator above 5 GPa; the ground stable structure of MoN2 has encapsulated N2 units, and is not the MoS2 type arrangement proposed by experimentalists; our predictions coupled with the XRD data allow the elucidation of the GaPO4 structure at 20 GPa
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29

Rodene, Dylan D. "Engineering of Earth-Abundant Electrochemical Catalysts." VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/6106.

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Alternative energy research into hydrogen production via water electrolysis addresses environmental and sustainability concerns associated with fossil fuel use. Renewable-powered electrolyzers are foreseen to produce hydrogen if energy and cost requirements are achieved. Electrocatalysts reduce the energy requirements of operating electrolyzers by lowering the reaction kinetics at the electrodes. Platinum group metals (PGMs) tend to be utilized as electrocatalysts but are not readily available and are expensive. Ni1-xMox alloys, as low-cost and earth-abundant transition metal nanoparticles (NPs), are emerging as promising electrocatalyst candidates to replace expensive PGM catalysts in alkaline media. Pure-phase cubic and hexagonal Ni1-xMox alloy NPs with increasing Mo content (0–11.4%) were synthesized as electrocatalysts for the hydrogen evolution reaction (HER). In general, an increase in HER activity was observed with increasing Mo content. The cubic alloys were found to exhibit significantly higher HER activity in comparison to the hexagonal alloys, attributed to the higher Mo content in the cubic alloys. However, the compositions with similar Mo content still favored the cubic phase for higher activity. To produce a current density of -10 mA/cm2, the cubic and hexagonal alloy NPs require over-potentials ranging from -62 to -177 mV and -162 to -242 mV, respectively. The cubic alloys exhibited over-potentials that rival commercial Pt-based electrocatalysts (-68 to -129 mV at -10 mA/cm2). The cubic Ni0.934Mo0.066 alloy NPs showed the highest alkaline HER activity of the electrocatalysts studied and therefore a patent application was submitted. Bulk Ni–Mo phases have been known as electrocatalysts for the HER for decades, while recently transition metal phosphides (TMPs) have emerged as stable and efficient PGM alternatives. Specifically, Ni2P has demonstrated good HER activity and improved stability for both alkaline and acidic media. However, Ni2P electrocatalysts are a compromise between earth-abundance, performance (lower than Ni–Mo and PGMs) and stability. For the first time Ni–Mo–P electrocatalysts were synthesized with varying atomic ratios of Mo as electrocatalysts for alkaline HER. Specific phases, compositions and morphologies were studied to understand the intrinsic properties of TMPs leading to high HER activity. The Ni1.87Mo0.13P and Ni10.83Mo1.17P5 NPs were shown to be stable for 10 h at –10 mA cm-2 with over-potentials of –96 and –82 mV in alkaline media, respectively. The Ni1.87Mo0.13P and Ni10.83Mo1.17P5 NPs exhibited an improved performance over the synthesized Ni2P sample (–126 mV at –10 mA cm-2), likely a result of the overall phosphorous content and hetero-structured morphologies. A strong correlation between phase dependence and the influence of Mo on HER activity needs to be further investigated. Furthermore, understanding the intrinsic properties of electrocatalysts leading to high water splitting performance and stability can apply electrocatalysts in other research applications, such as photoelectrochemical (PEC) water splitting, water remediation and sustainable chemical processing applications. Contributions to photocatalytic water remediation and electrochemical chlorinated generation to halogenate pyridone-based molecules are reported. Electrochemical techniques were developed and reported herein to aid in understanding electrochemical performance, chemical mechanisms and the stability of electrocatalysts at the electrode-electrolyte interfaces.
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30

Memarpour, Arashk. "A study on the Submerged Entry Nozzels (SEN) respecting clogging and decarburization." Licentiate thesis, KTH, Tillämpad processmetallurgi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-25110.

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The submerged entry nozzle (SEN) has been used to transport the molten steel from tundish to the mould. The main purpose of the SEN usage is both to prevent oxygen and nitrogen pick-up by molten steel and to achieve the desired flow condition in the mould. Therefore, the SEN can be considered as a vital factor for a stable casting process and the steel quality. Furthermore, the steelmaking processes occur at high temperatures around 1873 K so the interaction between the refractory materials of the SEN and molten steel is unavoidable. Therefore, the knowledge of the SEN behaviors during pre-heating and casting is necessary for the design of the steelmaking processes. The internal surfaces of modern SENs are coated with a glass/silicon powder layer to prevent the SEN graphite oxidation during pre-heating. The effects of the interaction between the coating layer and the SEN base refractory materials on clogging were studied in supplement 1. The results of the study indicated the penetration of the formed alkaline-rich glaze into the Alumina/graphite base refractory during pre-heating. More specifically, the alkaline-rich glaze reacts with graphite to form carbon monoxide gas. Thereafter, dissociation of CO at the SEN/molten metal interface takes place. This leads to reoxidation of dissolved REM (Rare Earth Metal), which form the “In Situ” REM oxides at the interface between the SEN and the REM alloyed molten steel. Also, the interaction of the penetrated glaze with alumina in the SEN base refractory materials leads to a formation of a high-viscous alumina-rich glaze during the SEN pre-heating process. This in turn, creates a very uneven surface at the SEN internal surface. The “In Situ” formation of the REM oxides together with the uneven internal surface of the SEN may facilitate the accumulation of the primary inclusions. Supplement 1 revealed the disadvantages of the glass/silicon powder layer. On the other hand the carbon oxidation is a main industrial problem for un-coated Alumina/Graphite Submerged Entry Nozzles (SEN) during pre-heating. This led to the proposal of a new refractory material for the SEN. In supplement 2, the effect of ZrSi2 antioxidant and the coexistence of antioxidant additive and (4B2O3 ·BaO) glass powder on carbon oxidation were investigated at simulated non-isothermal heating conditions in a  controlled atmosphere. Also, the effect of ZrSi2 antioxidant on carbon oxidation was investigated at isothermal temperatures at 1473 K and 1773 K. The specimens’ weight losses and temperatures were plotted versus time and compared to each others. The thickness of the oxide areas were measured and also examined using XRD, FEG-SEM and EDS. The coexistence of 8 wt% ZrSi2 and 15 wt% (4B2O3 ·BaO) glass powder of the total alumina/Graphite base refractory materials, presented the most effective resistance to carbon oxidation. The 121% volume expansion due to the Zircon formation during heating and filling up the open pores by (4B2O3 ·BaO) glaze during green body sintering led to an excellent carbon oxidation resistance. In supplement 3, decarburization behaviors of Al2O3-C, ZrO2-C and MgO-C refractory materials constituting a commercial Submerged Entry Nozzle (SEN), have been investigated in different gas atmosphere consisting of CO2, O2 and Ar. The (CO2/O2) ratio values were kept the same as it is in propane combustion flue gas at Air Fuel Ratio (AFR) values equal to 1.5 and 1 for both Air-fuel and Oxygen-fuel combustions. Laboratory experiments were carried out non-isothermally in the temperature range 873 K to 1473 K at 15 K/min followed by isothermal heating at 1473 K for 60 min. The decarburization ratio (α) values of the three refractory types were determined by measuring the weight losses of the samples. The results showed that the decarburization ratio (α) values of the MgO-C refractory became 3.1 times higher for oxygen-fuel combustion compared to air-fuel combustion both at AFR equal to 1.5 in the temperature range 873 K to 1473 K. The decarburization ratio (α) values for Al2O3-C samples were the same as for the isothermal heating at 1473 K and non-isothermal heating in the temperature range 473  to 1773 K with a 15 K/min heating rate. It substantiates the SEN preheating advantage at higher temperatures for shorter holding times instead of heating at lower temperatures for longer holding times. Jander’s diffusion model was proposed for estimating the decarburization rate of Al2O3-C refractory in the SEN. The activation energy for Al2O3-C samples heated at AFR equal to 1.5, for air-fuel and oxygen-fuel combustions were found to be 84.5 KJ/mol and 95.5 KJ/mol respectively during non-isothermal heating in the temperature range 873 K to 1473 K.<br>QC 20101008
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31

PEREIRA, CLOTILDE C. "Desenvolvimento de membranas aniônicas obtidas por enxertia via irradiação para aplicação em células a combustível alcalinas." reponame:Repositório Institucional do IPEN, 2017. http://repositorio.ipen.br:8080/xmlui/handle/123456789/27979.

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Submitted by Marco Antonio Oliveira da Silva (maosilva@ipen.br) on 2017-11-09T12:16:30Z No. of bitstreams: 0<br>Made available in DSpace on 2017-11-09T12:16:30Z (GMT). No. of bitstreams: 0<br>As membranas de troca aniônica são uma alternativa promissora para o desenvolvimento de eletrólitos mais eficientes para células a combustível alcalinas. Em geral, as membranas de troca aniônica são ionômeros capazes de conduzir íons hidroxila devido aos grupos quaternário de amônio e têm como característica elevado pH equivalente. Com o objetivo de desenvolver membranas aniônicas química e termicamente estáveis, com satisfatória condutividade iônica para aplicação em células a combustível alcalinas, as membranas aniônicas foram sintetizadas a partir de polímeros base de polietileno de baixa densidade (LDPE), polietileno de ultra alto peso molecular (PEUHMW), poli(etileno-co-tetrafluoroetileno) (PETFE) e poli(tetrafluoroetilleno-co-hexafluoroetileno) (PFEP) previamente irradiados nas fontes de radiação gama de 60Co ou com feixe de elétrons, para enxertia do monômero de estireno e funcionalizados com trimetilamina para incorporação dos grupos quaternário de amônio. As membranas resultantes foram caracterizadas por espectroscopia de ressonância paramagnética eletrônica (EPR), espectroscopia Raman, termogravimetria (TG), espectroscopia de impedância eletroquímica (EIS), além da determinação do grau de enxertia, capacidade de absorção de água por gravimetria e capacidade de troca iônica, por titulação. As membranas sintetizadas com os polímeros LDPE e UHMWPE pré-irradiados a 70 kGy com feixe de elétrons e armazenadas a baixa temperatura (-70 °C) por até 10 meses, mostraram resultados de condutividade iônica, quando na forma (OH-), de 29 mS.cm-1 e 14 mS.cm-1 a 65 °C, respectivamente. Os filmes de PFEP irradiados no processo simultâneo mostram níveis de enxertia insuficientes para a síntese de membranas aniônicas, necessitando maiores estudos para aperfeiçoar os processos de irradiação e enxertia. As membranas baseadas em PETFE, pré-irradiadas a 70 kGy com feixe de elétrons e armazenadas a baixa temperatura (-70 °C) por até 10 meses, mostraram maior condutividade iônica, quando na forma hidroxila (OH-), com valores de condutividade iônica entre 90 mS.cm-1 e 165 mS.cm-1 na faixa de temperatura entre 30 e 60 °C. Estes resultados mostraram que membranas de LDPE, UHMWPE e PETFE são eletrólitos promissores para a aplicação em células a combustível alcalinas.<br>Dissertação (Mestrado em Tecnologia Nuclear)<br>IPEN/D<br>Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
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32

Šafář, Martin. "Trvanlivost alkalicky aktivovaných systémů." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2015. http://www.nusl.cz/ntk/nusl-217135.

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Alkali activated binders have the potential to become an alternative construction material to ordinary portland cement binders. This thesis concentrates on durability testing of alkali activated blast furnace slag and fly ash based concrete. The chosen aspects of durability included sulfate resistance, acid resistance, carbonation, freeze-thaw resistance, frost-salt resistance and porosity. Microstructural changes and formation of new crystalline phases were observed using XRD and SEM-EDX analysis. Potential application of the tested material from the durability point of view was evaluated by comparison with a reference ordinary portland cement based concrete.
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33

Pickrell, Gary Robert. "High temperature alkali corrosion kinetics of low expansion ceramics /." This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06062008-163208/.

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34

Reinhold, Catherine Janey. "Reduced species in alkali metal loaded framework materials." Thesis, University of Birmingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289728.

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35

Bordeian, Georgeta Simona. "Characterisation and properties of alkali activated pozzolanic materials." Thesis, Sheffield Hallam University, 2000. http://shura.shu.ac.uk/19371/.

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Many of the waste materials produced from modem heavy industries are pozzalans, which develop cementitious properties when finely divided in the presence of free lime. This property allows a potential industrial use for this waste as a cement replacement material in concrete. An example of such a waste material is blast furnace slag from the smelting of iron and steel. The US produces 26 million tons of blast furnace slag annually. Most of the slag is slowly cooled in air and it makes a poor pozzolan. Only 1.6 million tons of the slag is available in the granulated form, which is suitable as a cementitious and pozzolanic admixture. Most European countries are well endowed with coal-fired power stations and this produces fly and bottom ash, flue gas desulphurisation (FGD) gypsum. However, less than 25% of the total ash from power stations has found an industrial use mainly in cement and concrete industry. This creates a massive waste-disposal problem. Disposal of unused fly ash in open tips and ponds, for example, creates pollution problems since the drainage of effluents from the ash in the deposit ponds threaten water supplies by polluting the ground water with traces of toxic chemicals. Recent research has concentrated on the alkali activation of waste pozzolanic materials, especially ground blast furnace slag. This thesis has investigated the alkali activation of low calcium fly ashes. These form very poor pozzolans and the alkali activation of the fly ash offers the opportunity for the large scale use of fly ash. Water glass was selected as a suitable activator for the fly ash. A comprehensive series of tests have been carried out to gain information on the effect of different parameters, such as proportion and composition of the constituent materials, curing conditions and casting methods, in developing high performance construction materials. Laboratory investigations were carried out to determine the following characteristics of alkali activated materials: density, water absorption, apparent porosity and coefficient of saturation, drying shrinkage, compressive creep, compressive, flexural and tensile splitting strength, dynamic modulus of elasticity, accelerated weathering (freeze-thaw cycle) resistance, fire resistance (temperatures up to 600&deg;C), microstructure, macrostructure and investigation of hydration phases by SEM, ED AX, Digital-mapping and X-ray diffraction. The influence of key parameters e.g. slag content, curing method, water/binder ratio and water glass hardener content on the mechanical properties were determined. Optimisation of the alkali-activation of fly ash materials was achieved by blending this with other pozzolans such as silica fume and slags. Mechanical properties were further improved by using moulding pressures and by thermal treatment. The use of short fibre reinforcements was investigated to overcome microcracking, volumetric deformation and creep in the materials. The free shrinkage and creep of the materials agree with the model developed by Mangat and Azari for fibre reinforced Portland cement composites. Other additives were also investigated to improve workability, frost and water resistance and physical properties of the alkali activated materials. The fundamental relationships between chemical composition, hydration phases,microstructure and engineering properties (strength, durability and stability) of alkali activated materials were investigated. It is clear that strength development is a function of the hydration products developed and these are affected by the mix composition and the curing temperature. The current work found parameters such as the Si/Al ratio, the Ca/Si ratio and the Na20 content to be important. These chemical parameters decide the principal phases in the hydration products formed in alkali activated materials, between calcium silicate hydrate (C-S-H) and zeolite of the form (R[2]0 n Al[2]O[3] x SiO[2] r H[2]O).Overall the thesis shows the great potential of alkali activated materials to produce high strength construction materials. Limitation in the shrinkage of the materials can be overcome by the use of fibre reinforcement. At the end of the thesis limitations and suggestions for further work are made.
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Li, Zihui. "Acid Leaching Resistance and Alkali Silica Reaction (ASR) of Alkali-Activated Cement Free Binders." Thesis, Clarkson University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10640300.

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<p> Recently, increased awareness of the significance of developing sustainable materials for construction has renewed the interest in exploring Alkali activated concrete (AAC), a concrete that contains no cement, but only industrial by-products such as fly ash and slag, as a low energy alternative to the conventional concrete. Although the feasibility of making alkali&ndash;activated concrete with acceptable strength and mechanical properties is well documented, the information regarding the long-term durability, including resistance to acid attack and alkali silica reaction (ASR), is far from comprehensive and there is a need to increase the understanding of these durability issues. In this dissertation, these durability issues are addressed, and improvements in this novel technology will increase acceptance in industry. This dissertation presents a comprehensive evaluation into the acid leaching resistance of Alkali-Activated Concrete (AAC) and Ordinary Portland Cement (OPC). The deterioration in AAC and OPC when exposed to different types of acid laden (organic and inorganic) environments are quantified by characterizing the strength degradation, mass change and visual appearances. The changes in microstructure development and chemical composition are examined and analyzed in order to determine the mechanism of deterioration. Additionally, the effect of the addition of nanoparticles on the mechanical properties and resistance to sulfuric leaching of Alkali Activated Slag concrete (AAS) are also explored in this study. </p><p> Furthermore, this dissertation summarizes the findings of an experimental evaluation of alkali silica reaction (ASR) in cement free alkali activated concrete (AAC). The susceptibility of AAC to deleterious ASR was evaluated in this study in accordance with relevant ASTM standards. This study also compares the resistance of AAC with ordinary portland cement concrete (OPC) while exposed to ASR under ASTM C 1293 and ASTM C1567 tests. In particular, the focus of this investigation is to assess the effectiveness of existing ASTM test methods in identifying the occurrence of ASR in alkali activated slag cement (AAS) concrete. In addition to that, influences of activator parameters including the effect of binder type, activator concentration, activator type and water content to the resistance of ASR in AAC were also evaluated. Finally, a scanning electron microscopic study coupled with EDX analyses was used to explain the mechanism of ASR occurrence in AAC and OPC.</p><p>
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37

Stjernberg, Jesper. "Degradation of mullite based materials by alkali containing slags." Licentiate thesis, Luleå : Division of Engineering Materials, Luleå University of Technology, 2008. http://epubl.luth.se/1402-1757/2008/41.

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38

Kane, Steven Daniel. "Degradation of cellulosic material by Cellulomonas fimi." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/10049.

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The world stocks of fossil fuels are dwindling and may be all but out before the end of the century. Despite this there is increasing demand for them to be used for transport, and the ever increasing green house gases which their use produces. Renewable and less environmentally damaging forms of fuel are needed. Biofuels, particularly bioethanol, are a possibility to subsidise or replace fossil fuels altogether. Ethanol produced from fermentation of starch sugars from corn are already in wide use. As this bioethanol is currently produced from crops such as corn and sugar cane, that puts fuel crops in direct competition for space and resources with food crops. This has led to increases in food prices and the search for more arable land. Hydrolysis of lignocellulosic biomass, a waste by-product of many industries, to produce the sugars necessary for ethanol production would ease many of the problems with current biofuels. Degradation of lignocellulose is not simple and requires expensive chemical pre-treatments and large quantities of enzymes usually from fungal species making it about 10 times more expensive to produce than corn starch bioethanol. The production of a consolidated bioprocessor, an organism able to degrade, metabolise and ferment cellulosic material to produce ethanol or other useful products would greatly reduce the cost currently associated with lignocellulosic biofuel. Cellulomonas fimi ATCC 484 is an actinomycete soil bacterium able to degrade efficiently cellulosic material. The US Department of Energy (DOE) released the genome sequence at the start of 2012. In this thesis the released genome has been searched, for genes annotated as encoding polysaccharide degrading enzymes as well as for metabolic pathways. Over 100 genes predicted to code for polysaccharide hydrolysing enzymes were identified. Fifteen of these genes have been cloned as BioBricks, the standard synthetic biology functional unit, expressed in E. coli and C. freundii and assayed for endo β-1,4-glucanase activity using RBB-CMC, endo β-1,4-xylanase activity using RBB-xylan, β-D-xylosidase activity using ONPX, β-D-cellobiohydrolase activity using ONPC and α-L-arabinofuranosidase activity using PNPA. Eleven enzymes not previously reported from C. fimi were identified as active on a substrate with the strongest activities being for 2 arabinofuranosidases (AfsA+B), 4 β-xylosidases (BxyC, BxyF, CelE and XynH), an endoglucanase (CelA), and 2 multifunctional enzymes CelD and XynF, active as cellobiohydrolases, xylosidases and endoxylanases. Four enzymes were purified from E. coli cell lysates and characterised. It was found that AfsB has an optimum activity at pH 6.5 and 45ºC, BxyF has optimum activity at pH 6.0 and 45ºC and XynH has optimum activity at pH 9.0 and 80ºC. XynF exhibited different optima for the 3 substrates with pH 6.0 and 60ºC for ONPC, pH 4.5 and 50ºC for ONPX and pH 5.5 and 40ºC for RBB-xylan. Searching the genome and screening genes for activities will help genome annotation in the future by increasing the number of positively annotated genes in the databases. The BioBrick format is well suited for rapid cloning and expression of genes to be classified. Searching and screening the genome has also given insights into the complex and large network of enzymes required to fully hydrolyse and metabolise the sugars released from lignocellulose. These enzymes are spread across many different glycosyl hydrolase families conferring different catalytic activities. The characterisation of these novel enzymes points towards a system adapted to not only a broad specificity of substrate but also environmental factors such as high temperature and pH. Genomic analysis revealed gene clusters and traits which could be used in the design of a synthetic cellulolytic network, or for the conversion of C. fimi into a consolidated bioprocessor itself.
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39

Jia, Jingshu. "Fabrication of high quality one material anode and cathode for water electrolysis in alkaline solution /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?EVNG%202008%20JIA.

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40

Sakulich, Aaron Richard Barsoum M. W. "Characterization of environmentally-friendly alkali activated slag cements and ancient building materials /." Philadelphia, Pa. : Drexel University, 2010. http://hdl.handle.net/1860/3209.

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41

Laracy, Michael Edward. "Valorization of boiler ash in alkali activated material." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/99582.

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Thesis: S.M., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2015.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 97-102).<br>For centuries the clay fired brick has been the most popular building material in India due to its local availability and low cost. Despite the growing demand for bricks, some negative environmental and social impacts surrounding its production raise concerns about its future use. In parallel, a growth in industry is generating a number of industrial wastes, such as boiler ash, which are often disposed of in ways that are harmful to the population and the environment. Due to its highly variable physical and chemical properties, boiler ash currently has no viable applications, providing an opportunity to identify a solution. This research seeks to partially solve both the brick and the waste problem by recycling boiler ash into masonry construction materials. This is accomplished using alkali activation, a low energy approach which relies on a chemical reaction to give the product its strength. The aim is to create a mix design which is robust enough to account for the variability in the ash and which produces a high performing masonry unit that is both economically and environmentally sustainable. This work presents two key contributions in service of this goal. Firstly, the physical, chemical, and mineralogical properties of three different boiler ashes are characterized to assess their suitability for alkali activation. Second, a robust mix is developed and the mechanical properties of the resulting products are studied. The boiler ash has many undesirable characteristics for alkali activation, including varying shape, large particle sizes ranging from 5-600 micron, loss on ignition between 8-35%, and less than 4% alumina. However, when combined with supplementary materials in the form of clay and lime, high compressive strengths are observed in the bricks made with all three ashes, demonstrating the robustness of the mix design. The final brick formulation with a solids phase of ash/clay/lime = 70/20/10, liquid to solid ratio = 0.45, and NaOH concentration = 2M produced bricks with compressive strengths between 11-15 MPa after 28 days curing at 30°C. Furthermore, early strength development is observed as more than 55% of the 28 day strength is achieved after one day curing.<br>by Michael Edward Laracy.<br>S.M.
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42

Ojedokun, Olalekan. "Durability properties of an alkali activated cementitious material." Thesis, Sheffield Hallam University, 2018. http://shura.shu.ac.uk/21933/.

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43

Morgado, J?nior Edisson. "Estudo de titanatos nanoestruturados obtidos por tratamento hidrot?rmico de ?xido de tit?nio em meio alcalino." Universidade Federal do Rio Grande do Norte, 2007. http://repositorio.ufrn.br:8080/jspui/handle/123456789/17675.

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Made available in DSpace on 2014-12-17T15:42:01Z (GMT). No. of bitstreams: 1 EdissonMJ.pdf: 6565731 bytes, checksum: 5d6fdd6db6fc25a30c6100d96fff1edc (MD5) Previous issue date: 2007-08-24<br>TiTanate NanoTubes (TTNT) were synthesized by hydrothermal alkali treatment of TiO2 anatase followed by repeated washings with distinct degrees of proton exchange. TTNT samples with different sodium contents were characterized, as synthesized and after heattreatment (200-800?C), by X-ray diffraction, scanning and transmission electron microscopy, electron diffraction, thermal analysis, nitrogen adsorption and spectroscopic techniques like FTIR and UV-Vis diffuse reflectance. It was demonstrated that TTNTs consist of trititanate structure with general formula NaxH2&#8722;xTi3O7?nH2O, retaining interlayer water in its multiwalled structure. The removal of sodium reduces the amount of water and contracts the interlayer space leading, combined with other factors, to increased specific surface area and mesopore volume. TTNTs are mesoporous materials with two main contributions: pores smaller than 10 nm due to the inner volume of nanotubes and larger pores within 5-60 nm attributed to the interparticles space. Chemical composition and crystal structure of TTNTs do not depend on the average crystal size of the precursor TiO2-anatase, but this parameter affects significantly the morphology and textural properties of the nanostructured product. Such dependence has been rationalized using a dissolution-recrystallization mechanism, which takes into account the dissolution rate of the starting anatase and its influence on the relative rates of growth and curving of intermediate nanosheets. The thermal stability of TTNT is defined by the sodium content and in a lower extent by the crystallinity of the starting anatase. It has been demonstrated that after losing interlayer water within the range 100-200?C, TTNT transforms, at least partially, into an intermediate hexatitanate NaxH2&#8722;xTi6O13 still retaining the nanotubular morphology. Further thermal transformation of the nanostructured tri- and hexatitanates occurs at higher or lower temperature and follows different routes depending on the sodium content in the structure. At high sodium load (water washed samples) they sinter and grow towards bigger crystals of Na2Ti3O7 and Na2Ti6O13 in the form of rods and ribbons. In contrast, protonated TTNTs evolve to nanotubes of TiO2(B), which easily convert to anatase nanorods above 400?C. Besides hydroxyls and Lewis acidity typical of titanium oxides, TTNTs show a small contribution of protonic acidity capable of coordinating with pyridine at 150?C, which is lost after calcination and conversion into anatase. The isoeletric point of TTNTs was measured within the range 2.5-4.0, indicating behavior of a weak acid. Despite displaying semiconductor characteristics exhibiting typical absorption in the UV-Vis spectrum with estimated bandgap energy slightly higher than that of its TiO2 precursor, TTNTs showed very low performance in the photocatalytic degradation of cationic and anionic dyes. It was concluded that the basic reason resides in its layered titanate structure, which in comparison with the TiO2 form would be more prone to the so undesired electron-hole pair recombination, thus inhibiting the photooxidation reactions. After calcination of the protonated TTNT into anatase nanorods, the photocatalytic activity improved but not to the same level as that exhibited by its precursor anatase<br>Titanatos nanoestruturados, particularmente TiTanatos NanoTubulares (TTNT), foram sintetizados por tratamento hidrot?rmico alcalino de TiO2-anat?sio seguido de repetidas lavagens com diversos graus de troca prot?nica. Amostras de TTNT com diferentes teores de s?dio foram caracterizadas na forma de p? seco e ap?s calcina??o (200-800?C) por difra??o de raios-X, microscopia eletr?nica de varredura e transmiss?o, difra??o de el?trons, an?lise t?rmica, adsor??o de nitrog?nio e t?cnicas espectrosc?picas de infravermelho e de reflet?ncia difusa no UV-Vis?vel. Demonstrou-se que tais materiais de paredes multilamelares s?o trititanatos de f?rmula geral NaxH2&#8722;xTi3O7?nH2O, retendo ?gua entre as lamelas. A remo??o de s?dio da estrutura reduz a quantidade de ?gua contraindo o espa?o interlamelar levando, combinado a outros fatores, ao aumento da ?rea e do volume de poros espec?ficos. Os TTNTs s?o materiais mesoporosos com duas contribui??es principais: poros menores que 10 nm devido ao volume interno dos nanotubos e poros entre 5 e 60 nm devido aos espa?os interpart?cula. A composi??o qu?mica e a estrutura cristalina do TTNT n?o dependem do tamanho de cristalito do TiO2-anat?sio precursor, todavia este par?metro afeta significativamente a morfologia e as caracter?sticas texturais do produto nanoestruturado. Tal depend?ncia foi racionalizada atrav?s de um mecanismo de dissolu??o-recristaliza??o que leva em conta a velocidade de dissolu??o do TiO2 de partida e sua influ?ncia sobre a taxa de crescimento de nanofolhas intermedi?rias em rela??o ? taxa de seu curvamento a nanotubos. A estabilidade t?rmica do TTNT ? definida pelo teor de s?dio e em pequena extens?o pelo tipo de anat?sio de partida. Foi demonstrado que o TTNT ap?s perder a ?gua intercalada entre 100 e 200?C se transforma pelo menos parcialmente num hexatitanato NaxH2&#8722;xTi6O13 intermedi?rio ainda nanotubular. A transforma??o t?rmica do tri- e hexatitanato nanoestruturados ocorre em maior ou menor temperatura e segue diferentes rotas dependendo do teor de s?dio. No caso de alto s?dio sinterizam e crescem at? grandes cristais de Na2Ti3O7 e Na2Ti6O13 na forma de bast?es e fitas acima de 600?C. No caso da amostra protonizada evoluem para nanotubos de TiO2(B) que facilmente se convertem em nanobast?es de anat?sio acima de 400?C. Al?m de hidroxilas e acidez de Lewis t?picos dos ?xidos de tit?nio, os TTNTs apresentam uma pequena contribui??o de acidez prot?nica capaz de se coordenar com a piridina a 150?C, e que ? perdida ap?s sua calcina??o e transforma??o ? anat?sio. O ponto isoel?trico do TTNT variou dentro da faixa 2,5- 4,0, indicando o comportamento de um ?cido fraco. Apesar de se revelar um semicondutor exibindo banda de absor??o t?pica no espectro de UV-vis?vel com energia de bandgap ligeiramente superior ao do respectivo TiO2-anat?sio precursor, os TTNTs apresentaram baixo desempenho fotocatal?tico na degrada??o de corantes cati?nico e ani?nico. Concluiu-se que a causa fundamental reside em sua estrutura de titanato lamelar que, em rela??o ? forma TiO2, apresentaria maior probabilidade de recombina??o do par el?tron-lacuna (e-/h+), inibindo as rea??es de fotoxida??o. A transforma??o do TTNT prot?nico ? nanobast?es de anat?sio melhorou a atividade fotocatal?tica, por?m ainda sem atingir o mesmo desempenho do TiO2-anat?sio precursor
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44

Hopkins, A. D. "Group 15/alkali metal complexes and applications to photoemissive materials." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604223.

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The research presented in this thesis falls into four related areas. The synthetic approach used in all studies was the stepwise deprotonation of primary amines and phosphines with Group 15 dimethylamido reagents to produce heterobimetallic Group 15/alkali metal complexes. The principal aim was to examine the decomposition of these species, potentially into photoemission alkali metal antimonate layers. After an initial introduction (Chapter 1) detailing previous methods of synthesis of imido heterobimetallic complexes and photodiode materials, there follows an experimental section (Chapter 2) in which all the experimental details of the various synthetic studies are collected. Chapter 3 deals with the synthesis and characterisation of a range of heterobimetallic complexes of antimony and heavy alkali metals using the stepwise deprotonation of primary amines. Then presented is the first application of the stepwise deprotonation technique to primary phosphines (Chapter 4), demonstrating a direct comparison with heterometallic imido cages. Also presented is the decomposition of the new phosphinidene complex produced into Zintl compounds, providing a low-temperature route to these species. The applications of a heterometallic Sb/Li phopshinidene complex and an Sb/Li Zintl compound to the formation of photosensitive alloys is investigated and measurements show that photoactive materials are accessible <I>via </I>this route. In Chapter 5 the decomposition of phosphinidene complexes into Zintl compounds is probed. The formation of heterocyclic anions of the type [(RP)<SUB>n</SUB>E]<SUP>-</SUP> (E=Sb, As) in various reactions of [E(NMe<SUB>2</SUB>)<SUB>3</SUB>] with [RP(H)Li]<SUB>n</SUB> and [RPH<SUB>2</SUB>] (R=cyclohexyl, tertiary butyl) suggests that Zintl compounds are generated <I>via </I>these species. In Chapter 6 the study shifts its focus to the synthesis of heterometallic As/alkali metal complexes containing [As<SUB>2</SUB>(NCy)<SUB>4</SUB>]<SUP>2-</SUP> anions (Cy=cyclohexyl) and the investigation of the co-ordination chemistry of this species. The theme of ligand synthesis is continued in Chapter 7, where anionic species containing P-P and P-As frameworks are developed.
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45

Matts, Ian Lawrence. "Multi-redox active polyanionic cathodes for alkali-ion batteries." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/104108.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2016.<br>This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>Cataloged from student-submitted PDF version of thesis.<br>Includes bibliographical references (pages 121-139).<br>In order for alkali-ion batteries to gain widespread adoption as the energy storage technology of choice for transportation and grid applications, their energy must be improved. One key step towards this necessary improvement is the development of new battery cathode materials. In this thesis, two classes of polyanionic materials are examined as candidate cathodes for alkali-ion batteries: Li-containing carbonophosphates for Li-ion batteries and Na-containing fluorophosphates for Na-ion batteries. High-throughput ab initio calculations have previously identified carbonophosphates as a new class of polyanionic cathode materials. Li₃MnCO₃PO₄ is the most promising candidate due to its high theoretical capacity, predicted multi-redox activity, and ideal voltage range. However, a major limitation of this material is its poor cyclability and experimental capacity. In this work Li₃Fe₀.₂Mn₀.₈CO₃PO₄ is synthesized to combine the high theoretical capacity of Li₃MnCO₃PO₄ with the high cyclability of Li₃FeCO₃PO₄. Li₃Fe₀.₂Mn₀.₈CO₃PO₄ outperforms both Li₃MnCO₃PO₄ and Li₃FeCO₃PO₄, showing a reversible capacity of 105 mAh/g with little capacity fade over 25 cycles. However, poor thermodynamic stability of these compounds, particularly at partially delithiated compositions, prevents carbonophosphates from being seriously considered as a viable Li-ion cathode. Fluorophosphate cathodes are currently one of the most promising polyanionic sodium-ion battery cathodes due to their high energy density and cyclability. To further improve fluorophosphate cathodes, their capacity must be increased by using Na sites that had not been accessed prior to this work. In this thesis, reversible electrochemical Na+ insertion into Na₃V₂(PO₄)₂F₃ is demonstrated. To further improve fluorophosphate cathodes by using its newly discovered insertion capacity, novel Na₃[M]₂(PO₄)₂F₃ cathodes, with {M = Fe, Ti, V}, are synthesized and evaluated. Seeing no improvement, the question of what specific mechanism limits fluorophosphate cathode capacity is addressed. For this, the synthesis, electrochemical characterization, and computational examination of a specifically designed test system, Na₃GaV(PO₄)₂F₃, is reported. This leads to the conclusion that large diffusion barriers at high sodiations impose a kinetic limit on Na+ insertion in fluorophosphate cathodes, as opposed to limits in transition metal redox activity.<br>by Ian Lawrence Matts.<br>Ph. D.
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46

Kang, ShinYoung. "Ab initio prediction of thermodynamics in alkali metal-air batteries." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/89952.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2014.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 93-100).<br>Electric vehicles ("EVs") require high-energy-density batteries with reliable cyclability and rate capability. However, the current state-of-the-art Li-ion batteries only exhibit energy densities near ~150 Wh/kg, limiting the long-range driving of EVs with one charge and hindering their wide-scale commercial adoption.1-3 Recently, non-aqueous metal-O₂ batteries have drawn attention due to their high theoretical specific energy.2, 4-6 Specifically, the issues surrounding battery studies involve Li-O₂ and Na-O₂ batteries due to their high theoretical specific energies of 3.5 kWh/kg (assuming Li 20 2 as a discharge product in Li-O₂ batteries) and 1.6 and 1.1 kWh/kg (assuming Na₂O₂ and NaO₂ as discharge products, respectively, in Na-O₂ batteries). Since the potential of Li-O₂ batteries as an energy storage system was first proposed in 1996,1 various studies have criticized and verified their shortcomings, such as their low power density, poor cyclability, and poor rate capability. ₇, ₈ Substantial research attempts have been made to identify the cause of the high overpotentials and electrolyte decomposition and to search for better cathode/electrolyte/anode and/or catalyst material combinations. However, Li-O₂ battery technology remains in its infancy primarily due to the lack of understanding of the underlying mechanisms. Therefore, we investigate the charging mechanism, which contributes to the considerable energy loss using first-principles calculations and propose a new charging mechanism based on experimental observations and knowledge concerning Li-ion and Na-ion batteries. Most studies on metal-O₂ batteries have mainly focused on Li-O₂ batteries. However, recently, the promising performance of Na-O₂ systems has been reported.₉, ₁₀ Although Na-O₂ batteries exhibit slightly lower theoretical specific energies than those of the Li-O₂ batteries as specified above, the chemical difference between the two alkali metals substantially distinguishes the electrochemistry properties of Na-O₂ and Li-O₂. In the Na-O₂ system, both NaO₂ and Na₂O₂ are stable compounds, while in the Li-O system, LiO₂ is not a stable compound under standard state conditions (300 K and 1 atm).₁₁, ₁₂ Presumably, due to this chemical difference, the Na-O₂ system has exhibited a much smaller charging overpotential, as low as 0.2 V, when NaO₂ is formed as a discharge product, compared with that in Li-O₂ system, >1 V. Such a low charging overpotential in Na-O₂ batteries demonstrates their potential as a next generation electrochemical system for commercially viable EVs .₉,₁₀ In this thesis, we study the thermodynamic stability of Na-O compounds to identify the phase selection conditions that affect the performance of Na-O₂ batteries.<br>by ShinYoung Kang.<br>Ph. D.
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47

Ali, Fatmah Abdullah Haider. "Examination of atomic scale structure and dynamics of amorphous materials by solid state NMR." Thesis, University of Kent, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.481489.

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48

Moraes, João Cláudio Bassan de. "Study on sugar cane straw ash (SCSA) in alkali-activated binders /." Ilha Solteira, 2017. http://hdl.handle.net/11449/152101.

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Orientador: Jorge Luís Akasaki<br>Resumo: Aglomerantes ativados alcalinamente (AAA) são obtidos da combinação de um precursor solido (geralmente um aluminosilicato) e uma solução alcalina de alta concentração. As vantagens de utilizar este novo tipo de aglomerante comparado ao cimento Portland, um aglomerante convencional, são as menores emissões de CO2, menor consumo de energia e a possibilidade de utilizar matérias prima renováveis e/ou resíduos. Neste sentido, este trabalho apresenta um novo resíduo da indústria da cada de açúcar: a folha de cana de açúcar. A folha apresenta um poder calorífico interessante; portanto, ela pode ser utilizada como biomassa para produzir energia através um processo de queima. Depois deste procedimento, é gerado um novo resíduo: a cinza de folha de cana de açúcar (CF). Esta cinza não apresenta uma destinação correta, então este trabalho tem como intenção utilizar esta cinza como material prima em AAA. A CF foi avaliada de duas formas: como precursor solido e como matéria prima para produzir a solução alcalina. No primeiro modo, a CF foi utilizada em sistemas combinados com a escória de alto forno (EAF) ativado com ambas soluções de NaOH e NaOH/silicato de sódio. No segundo modo, a CF foi utilizada como fonte de sílica para produzir a solução alcalina com o NaOH em AAA baseados em EAF. Os sistemas foram estudados através da resistência a compressão de argamassas e pelo estudo da microestrutura de pastas. Ensaios realizados para avaliar a microestrutura foram a difração de raios-X (DRX)... (Resumo completo, clicar acesso eletrônico abaixo)<br>Doutor
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49

Aponte, Cecilio (Cecilio Aponte III). "Decreasing water absorption in and environmental analysis of alkali activated bricks." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98644.

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Thesis: S.B., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2015.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 34-36).<br>Alkali activated bricks offer an alternative to traditional clay fired bricks for use in construction in the developing world. Previous work in this lab focused on creating a robust mix formulation to create these bricks, but they faced high water absorption and were not optimized under pressure molding conditions. The motivation for the work on alkali-activated bricks is based on the claim that they have a lower environmental burden, but this claim has not yet been verified for this formulation. Thus, this thesis focused on the effects of controlled testing of formation pressure and particle size distribution on brick performance and understanding the relative environmental impacts of clay fired bricks and alkali activated bricks. It was found that water absorption and compressive strength have a strong dependence on forming pressure, with 3-day compressive strengths ranging from 7MPa to 27MPa and water absorption from 35% to as high as 60% as forming pressure increased from 5 to 35Mpa. Sieving of the ash used in the bricks to control for particle size distribution had a minimal effect on performance, but the similarity is attributed to the fact that packing density within the selected particle size ranges were similar. Further testing on controlled mixing of particle sizes is needed to see if better performance can be obtained. Life cycle assessment results verify the claim that the bricks perform better from an environmental perspective, but also show the dependence of that performance on variables such as lime content or kiln efficiency.<br>by Cecilio Aponte.<br>S.B.
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50

Stefancic, Ales. "Synthesis and characterization of alkali-metal reduced polycyclic aromatic hydrocarbon based materials." Thesis, Durham University, 2017. http://etheses.dur.ac.uk/12339/.

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The reduction chemistry of polycyclic aromatic hydrocarbon (PAH) based materials is well established and has been investigated for more than a century. A frequently applied reduction method is treatment of the PAH by alkali metals, where an electron from the alkali metal is transferred to the π-system of the PAH. Recently it has been found that these reduced species can possess intriguing magnetic and electronic properties in the solid state, e.g. pentacene derivatives are excellent organic semiconductors and triphenylides are low-dimensional antiferromagnets. This topic has also attracted considerable attention since superconductivity was reported in alkali-metal reduced PAHs synthesised by solid-state techniques. However, the unavailability of well-crystalline and single-phase materials, which would permit the unambiguous identification of the superconducting phase and disclose the origin of superconductivity, has severely hindered progress in this research direction. In this thesis the reduction of PAHs with potassium, rubidium and caesium metals was carried out in aprotic coordinating organic solvents. Single crystalline and polycrystalline phase-pure, solvent containing- and solvent-free reduction products were successfully isolated for the first time. Crystal structures were determined with single-crystal and powder X-ray diffraction, magnetism was studied with Superconducting Quantum Interference Device (SQUID) magnetometry and electron paramagnetic resonance (EPR) spectroscopy, and charge transfer was followed with infrared (IR) and Raman spectroscopies. The synthesised materials exhibit a variety of magnetic properties, spanning canted-antiferromagnetism, ferromagnetism, low-dimensional magnetism and diamagnetism. A detailed structural analysis was performed in order to establish magnetostructural correlations. This study has expanded the family of well characterised alkali-metal reduced PAH based materials and gives an insight into the structures and magnetism of this family of compounds.
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