Co-mineralization of alkaline-earth carbonates and silica [Elektronische Ressource] / vorgelegt von Matthias Kellermeier
449 Pages
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Co-mineralization of alkaline-earth carbonates and silica [Elektronische Ressource] / vorgelegt von Matthias Kellermeier

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Published 01 January 2011
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Co-Mineralization of Alkaline-Earth
Carbonates and Silica
Dissertation
zur Erlangung des Grades
Doktor der Naturwissenschaften (Dr. rer. nat.)
der Naturwissenschaftlichen Fakultät IV
Chemie und Pharmazie
Universität Regensburg

vorgelegt von
Matthias Kellermeier
Regensburg 2011










Promotionsgesuch eingereicht am: 03. März 2001
Promotionskolloquium am: 01. April 2011

Die Arbeit wurde angeleitet von Prof. Dr. Werner Kunz.

Prüfungsausschuss:
Vorsitzender: Prof. Dr. Dominik Horinek
1. Gutachter: Prof. Dr. Werner Kunz
2. Gutachter: Prof. Dr. Juan Manuel García-Ruiz
3. Gutachter: Prof. Dr. Arno Pfitzner




Preface
“Was lange währt, wird endlich gut” – this famous German saying (or its English
equivalent “Good things come to those who wait”) probably applies very well to most
doctoral studies and, in particular and hopefully, also to the present work. One of the
main difficulties in the course of a PhD thesis is indeed to recognize the point at which
enough or as much details as reasonably possible have been gathered on a subject and
the time has come to start writing the results down. Certainly, open questions will
always remain and bother a researcher, but this is actually what the fascination of
science is all about.
This thesis is part of the outcome of studies performed between November 2005 and
February 2011 at the Institute of Physical and Theoretical Chemistry of the University
of Regensburg. Some of the work presented in the following was done during several
stays of the author at the Laboratorio de Estudios Cristalográficos (LEC) in Granada,
Spain, a research institute belonging to the Spanish council of science (IACT-CSIC) as
well as the University of Granada. The thesis was written in a way that each chapter
serves as a manuscript draft which has either been already published in a shortened form
as an article in a scientific journal, or is intended to be submitted in the near future.
Therefore, individual chapters have their own abstract, introduction, and conclusion.
This main body of the work (Chapters 2-9) is preceded by a section devoted to
gradually guide the reader to the topic, define the central goals of the work, and provide
background information required to understand the implications of the results (Chapter
1). Eventually, the major conclusions drawn in each chapter are recapitulated and
suggestions for possible future studies are given (Chapter 10).
The achievements made in the course of this PhD project would not have been possible
without the valuable help of many people who became involved in terms of
experimental work and/or by advancing the development and formulation of concepts. It
was a pleasure to cooperate with all of them and it is a natural must to acknowledge
their contributions.
First of all, I wish to thank my supervisor Prof. Dr. Werner Kunz for the opportunity to
work in his group and the confidence to allow me to work independently and pursue my


own ideas, as well as the financial support over the years. I truly appreciate his ongoing
interest in the progress of the different projects and enthusiasm about the results, his
eagerness to look across the borders of the topic and his ability to pinpoint essentials
when things got complicated.
Likewise, I owe a great debt of gratitude to Prof. Dr. Juan Manuel García-Ruiz (LEC
Granada) who, though usually being far away, always had an open ear for my questions,
invited me to come to Granada and let me benefit from his enormous expertise
concerning silica biomorphs and crystal growth in general. He helped a lot in the
ongoing evaluation and interpretation of the many data collected, largely enhanced my
understanding of precipitation phenomena, and often motivated me to proceed with the
work. Also, I would like to thank Dr. Emilio Melero-García for the innumerable
discussions we had, which kept me thinking hard and often led to new perspectives and
theories that are reflected in the text and conclusions of this thesis. In particular, Emilio
provided some of the microscopy data presented in Chapter 6 and contributed
substantially to the writing of Chapter 8 as well as the design of the methodical
approach described therein, but I wish to thank him too simply for being a friend.
Moreover, I am indebted to JuanMa, Emilio and the whole staff of LEC for their
hospitality during my stays, the great time we had, and assistance during the
experiments conducted in their lab. Special thanks thereby go to Dr. Duane
Choquesillo-Lazarte for acquiring XRD data and the staff at the electron microscopy
unit of the University of Granada for measurement time and support.
Further acknowledgement is addressed to Dr. Denis Gebauer and Prof. Dr. Helmut
Cölfen (University of Konstanz) for collaborating in the field of pre-nucleation clusters
and their brightness in developing the model of aggregation-based nucleation. In this
context, I am also utterly grateful to Antje Völkel for performing the ultracentrifugation
experiments.
In addition, I would like to thank Dr. Anna Carnerup and Prof. Dr. Stephen Hyde
(Australian National University, Canberra) for introducing me to the world of
biomorphs in the course of my visit to ANU during my diploma thesis, and the helpful
advice they provided when elaborating the role of additives in biomorph formation.
Beyond that, the numerous different techniques employed throughout this thesis
required a number of cooperations with experts in the corresponding areas, which I
honestly appreciate. In particular, I thank Dr. Reinhard Rachel (University of

Regensburg) for teaching me how to operate a transmission electron microscope and
granting generous access to his machine, as well as for preparing thin sections of
biomorphs. Dr. Markus Drechsler (University of Bayreuth) is acknowledged for the vast
amount of time he spent on cryo-TEM analyses of the many samples with which I came
to him. I also wish to express my gratitude to Prof. Dr. Ishi Talmon and his co-workers
Drs. Judith Schmidt and Ellina Kesselman at the Technion Haifa for carrying out
excellent cryo-TEM studies on CaCO clusters. Further thanks go to Benjamin Gossler, 3
Martina Heider and Werner Reichstein (University of Bayreuth) who allowed me to
regularly use their superior scanning electron microscope and provided valuable support
during the measurements. Prof. Dr. Lorenz Kienle (University of Kiel) and his team
helped with sophisticated high-resolution TEM, EDX and electron diffraction studies on
both calcium carbonate and biomorph samples. Dr. Heiner Santner (Anton Paar GmbH,
Graz) acquired SAXS spectra of cluster solutions and accomplished primary data
handling. I am furthermore pleased to thank Dr. Martina Andratschke and Prof. Dr.
Arno Pfitzner for powder diffraction measurements, Dr. Thomas Burgemeister and Fritz
Kastner for collecting NMR spectra, and Hannes Krauss as well as Dr. Rainer Müller
for help concerning IR measurements (all University of Regensburg).
Another crucial brick in the construction of this thesis was the access to different
synchrotron radiation facilities. In this respect, I would like to thank the evaluation
committees of HASYLAB/DESY (Hamburg) and ELETTRA (Trieste) for allocating
beamtime and Drs. Edmund Welter, Thomas Wroblewski (both HASYLAB), Alberto
Cassetta, and Luisa Barba (both ELETTRA) for technical support at the beamlines. I am
greatly indebted to Dr. André Rothkirch (HASYLAB) for his interest in our research
and for providing a software tool that enabled automated evaluation of EDXRD data.
Roger Kutta (University of Regensburg) is acknowledged for programming routines
which facilitated data processing and graphical illustration. I also thank Prof. Dr.
Wolfgang Bensch and his group (University of Kiel) for kindly introducing us to the
EDXRD setup at DESY and assistance in the design and setup of the experiments.
Cordial thanks are devoted to all colleagues at the Institute of Physical and Theoretical
Chemistry for the pleasant working climate and ongoing socializing in the course of the
time I spent there. In particular, I would like to thank my lab mate Fabian Glaab for the
congenial, though not always calm atmosphere we had in our office and the unhesitant
help he offered me whenever I needed it. Likewise, I wish to acknowledge Josef


Eiblmeier for assisting with experiments and other issues during the final stages of this
thesis, Alexander Stoppa for support in various aspects, Alina Voinescu for fruitful
collaboration in the field of silica biomorphs, Björn Bartel for performing SEM and
EDX analyses, Martin Fleischmann for the preparation of biomorphs and the acquisition
of some of the SEM images shown in this work, as well as the staff of the mechanical
and electronic workshops for their technical help. Aside from the topics addressed in the
following chapters, the research performed in the framework of this thesis was
concerned also with thematically distinct projects. In this context, I would like to thank
Regina Klein, Dr. Oliver Zech and Dr. Rainer Müller for their excellent cooperation in
the fields of surfactants, ionic liquids and alginate hydrogels. Special thanks further go
to Hannes Krauss for useful advices regarding graphics and design.
This work was partially funded by the Fonds der Chemischen Industrie and I appreciate
their granting of a two-year scholarship.
Finally, I would like to thank Prof. Dr. Juan Manuel García-Ruiz and Prof. Dr. Arno
Pfitzner for their willingness to be examiners of this thesis.
Warmest thanks are reserved for my family and friends, with whom I spent wonderful
and relaxing hours away from work. Above all, I owe deepest gratitude to Regina and
my parents, who always took care of me in whatever respect and gave me strength to
carry on. This thesis would probably never have been completed without their support,
and it is therefore dedicated to them.

Matthias Kellermeier, Regensburg, February 2011.









Table of Contents
Chapter 1 General Background............................................................... 1
1.1 Introduction..........................................................................................................1
1.2 Aim of the Thesis ...............................................................................................17
1.3 Calcium Carbonate Precipitation ....................................................................18
1.4 Silica Biomorphs ................................................................................................26
1.5 References...........................................................................................................41
Chapter 2 Stabilization of Amorphous Calcium Carbonate in
Silica-Rich Environments..................................................... 49
2.1 Abstract ..............................................................................................................49
2.2 Introduction........................................................................................................49
2.3 Experimental Section.........................................................................................52
2.3.1 Materials .........................................................................................................52
2.3.2 Sample Preparation52
2.3.3 Analytical Methods53
2.3.3.1 Transmission Electron Microscopy............................................................53
2.3.3.2 Scanning Electron Microscopy ..................................................................54
2.3.3.3 Dynamic Light Scattering ..........................................................................54
2.3.3.4 Turbidity Measurements ............................................................................55
2.3.3.5 X-Ray Diffraction and IR Spectroscopy ....................................................55
2.4 Results.................................................................................................................55
2.4.1 Effect of Silica on Growing ACC Particles55
2.4.2 Aggregation Behavior of Silica-Coated ACC Nanoparticles .........................61
2.4.3 Leaching Experiments ....................................................................................63
2.4.4 Effect of Silica on the Transformation of ACC to Stable Calcite ..................65
2.4.5 pH Measurements ...........................................................................................74
2.5 Discussion ...........................................................................................................75
2.6 Conclusion ..........................................................................................................81
2.7 References82

Chapter 3 Biomimetic Crystallization in Purely Inorganic
Precipitation Systems ........................................................... 87
3.1 Abstract ..............................................................................................................87
3.2 Introduction........................................................................................................87
3.3 Experimental Section.........................................................................................91
3.3.1 Crystallization Experiments............................................................................91
3.3.2 Analytical Methods92
3.3.2.1 Visual Observations ...................................................................................92
3.3.2.2 Light Microscopy .......................................................................................93
3.3.2.3 Electron Microscopy ..................................................................................93
3.3.2.4 X-Ray Diffraction ......................................................................................94
3.4 Results.................................................................................................................94
3.4.1 Crystallization of CaCO from Silica-Coated ACC .......................................94 3
3.4.2 Morphology and Texture of the Final Crystalline Products ...........................98
3.4.3 Crystal Polymorphism and Composition......................................................103
3.5 Discussion .........................................................................................................106
3.6 Conclusion ........................................................................................................111
3.7 References113
Chapter 4 Capturing Calcium Carbonate Pre-Nucleation Clusters
in Alkaline Silica Sols ......................................................... 121
4.1 Abstract ............................................................................................................121
4.2 Introduction......................................................................................................121
4.3 Experimental Section.......................................................................................125
4.3.1 Materials and Sample Preparation ................................................................125
4.3.1.1 Preparation of Solutions...........................................................................125
4.3.1.2 Precipitation Experiments ........................................................................125
4.3.2 Cryo-TEM.....................................................................................................126
4.3.3 Dynamic Light Scattering.............................................................................127
4.3.3.1 Experimental and Data Evaluation...........................................................127
4.3.3.2 Separation of Cluster Aggregates by Centrifugation ...............................128
4.3.4 Small-Angle X-Ray Scattering .....................................................................129
4.3.4.1 Experimental ............................................................................................129
4.3.4.2 Data Analysis by the IFT Method............................................................130
4.3.4.3 Determination of Particle Sizes by Guinier-Type Plots ...........................131