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Characterization of Some Natural and Synthetic Materials with Silicate Structures

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Characterization of Some Natural and Synthetic Materials with Silicate Structures ISSN: 1402-1757 ISBN 978-91-7439-XXX-X Se i listan och fyll i siffror där kryssen är LICENTIATE T H E SIS Department of Engineering Sciences and Mathematics Division of Materials Science Edwin Escalera Mejia Characterization of Some Natural and Synthetic Materials With Silicate Structures With Edwin Escalera Mejia Characterization of Some Natural and Synthetic Materials ISSN: 1402-1757 ISBN 978-91-7439-553-2 Characterization of Some Natural and Luleå University of Technology 2013 Synthetic Materials With Silicate Structures Edwin Escalera Mejia Characterization of Some Natural and Synthetic Materials With Silicate Structures Edwin Escalera Mejia Luleå University of Technology Department of Engineering Sciences and Mathematics Division of Materials Science Printed by Universitetstryckeriet, Luleå 2013 ISSN: 1402-1757 ISBN 978-91-7439-553-2 Luleå 2013 www.ltu.se Abstract The present thesis deals with characterization of silicate structures with a determined morphology and structure such as ordered mesoporous silica and layered silicates. Mesoporous silica groups are amorphous solids exhibiting highly ordered pore structures with narrow pore size distributions and large surface areas. Porous materials are used in various applications such as in adsorption, separation, catalysis, molds for templating, etc. Another interesting group of layered materials are crystal silicates with minerals of natural origin. The silicates have a structure that consists of stacked layers in which planes of oxygen atoms coordinate to cations such as Si4+, Al3+, Mg2+, Fe3+ to form two dimensional sheets. The coordination of cations in adjacent sheets typically alternates between tetrahedral and octahedral. The properties and uses of the clays vary widely due to the differences in their structure and composition. Some important applications are paints, adsorption, intercalation, removal of pollutants from water and in ceramic industry. The thesis consists of two parts. In the first study characterization of synthesized and functionalized ordered mesoporous silica were performed. Mesoporous silica with a large surface area on which organic functional groups are grafted was used to synthesize cobalt nanoparticles. Investigation by SEM and TEM showed hexagonal particles, with a pore size about 10 nm. The functionalization of the silica was studied by FTIR and TG/DTA techniques and the obtained nanoparticles were characterized by XRD, TEM and EDX analysis. In the second study, an extended literature review on properties of clays is presented. Samples from three different clay deposits, Ivirgarzama (IC), Entre Rios (EC) and Uspha-Uspha (U) from Bolivia were characterized by different experimental techniques in order to assess their relevant features. The chemical and mineralogical analysis showed that the clays consist mainly of kaolinite and illite along with quartz in different amounts. Also, certain amounts of feldspar, iron and magnesium are present in the clays and with predominance in the EC clay. Thermal analysis (DSC/TG and dilatometer) and XRD were used to study the phase transformations and their microstructural evolution at sintering. The EC clay with a high alkali and iron content influenced both the onset of liquid formation and the onset of sintering. Mullite is a crystalline phase that strengthens the ceramics and it was formed in all the studied clays. Based on these results, the EC and U clays provide required characteristics that enable them for use in the fabrication of products with red tonality, especially bricks, roofing tiles and rustic floor tiles. The IC clay with relatively low iron content and with relatively good refractoriness can be used for production of firebricks and also for partially replacing kaolin and silica in white firing ceramics. Thus, the clays from Ivirgarzama, Entre Rios and Uspha- Uspha are promising raw materials and they should be considered as valuable resources for the production of building ceramics. ii iii Preface This licentiate thesis is a part of my PhD studies carried out at the division of Materials Science at Luleå University of Technology, Sweden. The aim of the thesis was to characterize synthetic mesoporous silicates and some natural clays from Bolivia, which can be suitable as building materials. The thesis is divided in two parts. The first study deals with the synthesis of mesoporous silica materials used as hard templates for synthesis of cobalt nanoparticles. The second part is about characterisation of natural clay minerals from Bolivia and their thermal behaviour. The thesis is compiled of the following papers: Synthesis of homogeneously dispersed cobalt nanoparticles in the pores of functionalized SBA-15 silica E. Escalera, M. A. Ballem, J. M. Córdoba, M-L. Antti and M. Odén Powder Technology 221 (2012) 359-364. High temperature phase transformation in Bolivian kaolinitic-illitic clays E. Escalera, R. Tegman, M-L. Antti and M. Odén Submitted to Applied Clay Science (2013). iv v Acknowledgements First of all, I would like to express my deep gratitude to my supervisor, Associate Professor Marta-Lena Antti, and my co-supervisor Professor Magnus Odén for their guidance and valuable ideas. I wish to express my gratitude to Dr. Ragnar Tegman, for his knowledge, good suggestions, and also for all discussions concerning to the second paper. I would like to thank Johnny Grahn for helping using the SEM instrument. Likewise, I want to thank all my colleagues at the Division of Materials Science. I want to thank Roberto Soto S., Coordinator of Project UMSS-ASDI-10 in Bolivia. And also I want to thank my colleagues at Chemistry-Department, FCyT-UMSS, for all good times shared. I am deeply indebted to my parents for their unconditional love, encouragement and support. I acknowledge the Swedish International Development Cooperation Agency, SIDA, for financial support for this project - Non Metallic Minerals as Resources for Development of Poor Bolivian Regions. vi vii PART ONE Mesoporous materials SBA-15 and its application in the synthesis of cobalt nanoparticles Contents 1. Introduction ......................................................................................................................................... 2 1.1 Mesoporous silica .......................................................................................................................... 2 1.2 Uses and applications .................................................................................................................... 3 2. Theoretical Background ...................................................................................................................... 4 2.1 Mesoporous silica SBA-15 ............................................................................................................ 4 2.1.1 Surfactants and silica precursors ............................................................................................ 4 2.2 Synthesis of mesoporous silica ...................................................................................................... 5 2.2.1 Formation ............................................................................................................................... 5 2.2.2 Hydrothermal treatment .......................................................................................................... 6 2.2.3 Removal of surfactants ........................................................................................................... 6 2.3 Functionalization of mesoporous silica ......................................................................................... 7 2.4 Metal incorporation in functionalized mesoporous silica .............................................................. 8 3. Materials and Methods ........................................................................................................................ 9 3.1 Materials ........................................................................................................................................ 9 3.2 Experimental procedure ................................................................................................................ 9 3.3 Characterization methods ............................................................................................................ 10 3.3.1 Scanning Electron Microscopy (SEM) ................................................................................. 10 3.3.2 Fourier Transform Infrared Spectroscopy (FTIR) ................................................................ 10 3.3.3 Termogravimetry and Differential Thermal Analysis (TG/DTA) ........................................ 10 3.3.4 Nitrogen adsorption/desorption isotherms............................................................................ 10 3.3.5 Transmission Electron Microscopy (TEM) .......................................................................... 10 3.3.6 X-ray diffraction (XRD) ....................................................................................................... 11 4. Summary of results ............................................................................................................................ 12 5. Conclusions ....................................................................................................................................... 14 References ............................................................................................................................................. 15 viii ix PART
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