IMPACT OF CITRATE IONS ON THE NUCLEATION AND GROWTH OF CaCO3.
[December 10, 2017]
We have published the last of a series of papers exploring the role of citrate ions in the crystallisation of calcium carbonates. Citrate ions are essential to the metabolism of aerobic organisms. Our study provide a deep understanding of the processes that may take place during biomineralization processes and how citrate ions affect the structure and stability of CaCO3 metastable precursor phases (i.e., amorphous calcium carbonate), the kinetics of calcite nucleation and growth, the crystallisation pathways of CaCO3 at low (~ 1 ˚C) temperatures and the morphology of calcite. Experiments were carried out at Diamond Light Source (Oxfordshire, UK) and Advanced Photon Source (Argonne National Laboratories, Chicago, USA). Papers have been published in Crystal Growth & Design and Advanced Functional Materials.
Besselink, R., Rodriguez-Blanco, J.D., Stawski, T.M., Benning, L.G., and Tobler, D.J. (2017) How short-lived ikaite affects calcite crystallisation. Crystal Growth & Design, 17, 6224-6230. [Link]
Montanari, G., Rodriguez-Blanco, J.D., Bovet, N., Stipp, S.L.S., and Tobler, D.J. (2017) Impact of citrate ions on the nucleation and growth of anhydrous CaCO3. Crystal Growth & Design, 17, 5269-5275. [Link]
Tobler, D.J., Rodriguez-Blanco, J.D., Dideriksen, K., Bovet, N., Sand, K.K., Stipp. S.L.S. (2015) Citrate Effects on Amorphous Calcium Carbonate (ACC) Structure, Stability, and Crystallization. Advanced Functional Materials, 25, 3081-3090. [Link]
SPECIAL ISSUE ABOUT RARE-EARTH CARBONATES
[November 20, 2017]
I am the Guest Editor for a special issue of the Journal Minerals (MDPI) about Rare-Earth Carbonates. This Special Issue has published open-access papers on recent progress in the study of rare-earth carbonates, focusing on crystallography, structure, spectroscopy, thermodynamics and kinetics of crystallisation. It included contributions combining experimental approaches as well as field-based studies. To access the papers included in this Special Issue, follow this link.
FROM ATOMS TO MINERALS: HOW CALCIUM CARBONATES FORM AND WHY WE SHOULD CARE.
[April 27, 2017]
On April 26, 2017 I was invited to give a keynote talk at the European Geosciences Union General Assembly 2017. In this talk, “From atoms to minerals: how calcium carbonates form and why we should care”, I presented a series of results obtained from synchrotron- and lab-based experiments that shed light on the mechanisms of formation of a number of biominerals (e.g., vaterite, calcite, aragonite, monohydrocalcite, dolomite). These results provide a detailed understanding of how calcium carbonate phases form during biomineralization processes, the effects of seawater ions and organics during the formation and transformation of biominerals, and the implications for past and future ocean chemistry, CO2 capture and storage and industrial mineral synthesis.
AN OVERVIEW OF THE FORMATION OF AMORPHOUS CALCIUM CARBONATE (ACC) AND VATERITE.
[January 1, 2017]
I have published a book chapter entitled “ACC and vaterite as metastable intermediates in the solution based crystallization of CaCO3”, which is part of the book “New Perspectives on Mineral Nucleation and Growth” (Springer). In this chapter I provide an overview of the formation of ACC and vaterite as key intermediates on the way to calcite, describing the influence of important parameters like pH, temperature, supersaturation and the presence of (in)organic additives on the structures, compositions and morphologies of crystalline CaCO3 phases, as well as possible mechanisms of transformation from ACC to vaterite and/or calcite. The book illustrates, based on a number of exemplary spotlights, the current state of the art in crystallization research, highlighting the important advances that have been made in our knowledge about mineralization phenomena taking place both in nature and in the laboratory.
Reference: Rodriguez-Blanco, J.D., Sand, K.K. and Benning, L.G. (2017) ACC and vaterite as metastable intermediates in the solution based crystallization of CaCO3. Chapter 5 of New Perspectives on Mineral Nucleation and Growth. Eds: Alexander van Driessche, Matthias Kellermeier, Liane G. Benning, Dennis Gebauer. Springer International Publishing. Switzerland. DOI: 10.1007/978-3-319-45669-0; eBook ISBN: 978-3-319-45669-0; Hardcover ISBN: 978-3-319-45667-6.
THANK YOUR LECTURER.
[December 9, 2016]
The Student Union of Trinity College Dublin recently carried out a “Thank your lecturer” survey to the Student Body asking for students to nominate lecturers for special thanks. Today I received an e-mail from the Education Officer at Trinity College Dublin Students’ Union stating that my students have nominated me. I would like to express my gratitude and appreciation to them for this. It has been a pleasure to share my time with them –all of them worked hard and always asked the right questions– and I wish them a brilliant future as professionals.
MOVING TO TRINITY COLLEGE, DUBLIN.
[July 10, 2016]
I am delighted to announce that on September 2016 I will join the Geology Department (School of Natural Sciences) of Trinity College Dublin (Ireland) as a lecturer in Nano-mineralogy.
Trinity College, founded in 1592, is the sole constituent college of the University of Dublin. As of 2015, it was ranked by the QS World University Rankings as the 78th best by the World and the best university in Ireland. Spread across 47 acres in Dublin’s city centre, Trinity has a 17,000-strong student body, 3,000 staff and over 107,000 alumni around the world. Of the student body, 16% come from outside Ireland and, of those, 40% are from outside the European Union, making Trinity’s campus cosmopolitan and bustling, with a focus on diversity.
HOW GYPSUM FORMS, AND HOW IT MIGHT TELL US MORE ABOUT WATER ON MARS
[April 1, 2016]
A new explanation of how gypsum forms may change the way we process this important building material, as well as allow us to interpret past water availability on other planets such as Mars. The multinational team examined the process using in situ and time resolved synchrotron-based X-ray scattering at Diamond Light Source (Harwell, UK), and identified and quantified each of the 4 steps of the formation process, highlighting specially that the initial moments in the reaction chain are of particular importance, because they determine the final properties of gypsum. Our work is reported in Nature Communications. [Press Release] [Paper] [News in EOS Magazine]
PHREEQC INTENSIVE COURSE FOR THE EU FP7 ITN NETWORK ISONOSE
[December 7, 2015]
From December 2-4, 2015 I was invited to teach a short specialist intensive course on the hydrogeochemical code PHREEQC for the EU FP7 Marie Curie Initial Training Network “IsoNose”. The IsoNose consortium consists of eight international partners and five associated partners in five countries (Germany, France, Ireland, UK, USA). The course included lectures and practical exercises, addressing the subjects like introduction to PHREEQC, solubility of minerals, speciation and saturation state of aqueous solutions, carbonates reaction, temperature and pressure, PHREEQC databases, among others. This course was taught at Zandvoort (the Netherlands) with Prof. Eric Oelkers from University College London.
INVITED TALK FOR THE SOCIETY OF SPANISH RESEARCHERS IN DENMARK
[November 13, 2015]
On November 13, 2015 I was invited to give a talk for the Society of Spanish Researchers in Denmark for the “Meet the Scientist” event that they held once per month. This time the topic of the session was “Nanotechnology: Beyond the Eye” and I contributed with a talk entitled “16 orders of magnitude: how the formation of minerals affects our planet and daily life“. I absolutely enjoyed the activity and was very glad to meet a very dynamic group of people.
KEYNOTE TALK AT THE FIFTH EUROPEAN CONFERENCE ON CRYSTAL GROWTH
[September 12, 2015]
On September 11, 2015 I gave a keynote talk about the “Mechanistic insights into the early stages of crystallization of rare-earth carbonates” at the Fifth European Conference on Crystal Growth (ECCG5), which was held in Bologne, Italy. I showed how we apply UV-Vis spectrophotometry combined with synchrotron-based pair distribution function (PDF) analysis, and other solid-state and spectroscopic techniques, to quantify changes in the REE3+-bearing carbonate local structure, composition, stability and crystallization pathways. This work has been carried out in collaboration with researchers at the Nano Science Center (University of Copenhagen) and the School of Earth and Environment, University of Leeds (United Kingdom), as part of a wider research aimed at understanding the crystallisation mechanisms and pathways of rare-earth carbonates.
THE EARLY STAGE MECHANISMS OF RARE-EARTH CARBONATES FORMATION
[June 12, 2015]
Rare-earths (REE) are moderately abundant in the Earth’s crust, but they are not concentrated enough to make them easily exploitable economically. In the last decade the supply of La and Nd for has become constrained while their demand for a variety of new technologies has grown. The most important REE source in the world is the Bayan Obo deposit, China, where more than 90% of world’s REE raw materials are extracted. However, there is a lack of basic data regarding the mechanisms of crystallization of REE-bearing carbonates and, in particular, the first stages of formation. This knowledge would be essential in the search of new REE-bearing deposits and also in the design of new separation methods of La and Nd during processing of REE ores. We have carried out a study on the formation and crystallization of La and Nd carbonates from aqueous solution. Our study describes for the first time the crystallization sequences of these REE-bearing carbonates.
Open-access paper published in Nanoscale “The role of amorphous precursors in the crystallization of La and Nd carbonates” available here.
Collaboration with Dr. Beatriz Vallina, Prof. Jesus A. Blanco and Prof. Liane G. Benning.
SOLVING THE DOLOMITE PROBLEM
[May 15, 2015]
Dolomite is a common mineral, but uncommonly resistant to our uncovering the nature of its formation. While perhaps not completely solved, the classic “dolomite problem” is at least now better understood. We have shown for the first time that the dolomite formation process begins with aqueous precipitation of a Mg-Ca amorphous phase, which transforms to proto-dolomite at 60-220 °C through a spherulitic growth mechanism. Proto-dolomite then transforms to dolomite through an Ostwald ripening-like process, at temperatures >140 °C.
Open-access paper published in American Mineralogist “A route for the direct crystallization of dolomite” available here. Also a short review about this study is available here.
BIOMINERALISATION BY EARTHWORMS
[April 28, 2015]
Many biominerals form from amorphous calcium carbonate (ACC), but this phase is highly unstable when synthesised in its pure form inorganically. Several species of earthworm secrete calcium carbonate granules which contain highly stable ACC. In this work we have shown that this ACC is highly heterogeneously distributed but also remarkably stable and can persist for several years. We have also shown that granules contain significant concentrations of amino acids and that granule elemental and amino acid concentration can vary significantly between granules.
Open-access paper published in Geochemical Transactions “Biomineralisation by earthworms: investigation into stability & distribution of ACC” available here.
Collaboration with Dr. Emma Versteegh and Prof. Mark Hodson.
HOW DOES CITRATE AFFECT AMORPHOUS CALCIUM CARBONATE STRUCTURE, STABILITY AND CRYSTALLISATION?
[April 11, 2015]
Understanding the role of citrate in the crystallization kinetics of amorphous calcium carbonate (ACC) is essential to explain the formation mechanisms, stabilities, surface properties, and morphologies of CaCO3 biominerals. It also contributes to deeper insight into fluid–mineral interactions, both in nature and for industrial processes. In this study, ACC formation and its crystallization are monitored in real time as a function of citrate (CIT) concentration in solution. Additionally, synchrotron radiation pair distribution function analyses combined with solid-state, spectroscopic, and microscopic techniques are used to determine the effect of CIT on ACC structure, composition, and size.
Paper published in Advanced Functional Materials “Citrate Effects on Amorphous Calcium Carbonate (ACC) Structure, Stability, and Crystallization” available here.