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Proto-Calcite and Proto-Vaterite in Amorphous Calcium Carbonates
Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Materials Chemistry.
Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Materials Chemistry.
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2010 (English)In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 49, no 47, 8889-8891 p.Article in journal (Refereed) Published
Abstract [en]

Amorphous order: Amorphous calcium carbonates (ACC) have an intrinsic structure relating to the crystalline polymorphs of calcite and vaterite. The proto-crystalline structures of calcite and vaterite (pc-ACC and pv-ACC) are analyzed by NMR (see picture), IR, and EXAFS spectroscopy, which shows that the structuring of ACC relates to the underlying pH-dependent equilibria.

Place, publisher, year, edition, pages
2010. Vol. 49, no 47, 8889-8891 p.
Keyword [en]
amorphous materials, calcium carbonate, crystallization, EXAFS spectroscopy, NMR spectroscopy
National Category
Inorganic Chemistry
Research subject
Materials Chemistry
Identifiers
URN: urn:nbn:se:su:diva-49833DOI: 10.1002/anie.201003220OAI: oai:DiVA.org:su-49833DiVA: diva2:379705
Available from: 2010-12-19 Created: 2010-12-19 Last updated: 2012-04-30Bibliographically approved
In thesis
1. Synthesis and modification of potential CO2 adsorbents: Amine modified silica and calcium carbonates
Open this publication in new window or tab >>Synthesis and modification of potential CO2 adsorbents: Amine modified silica and calcium carbonates
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The prospect of rapid changes to the climate due to global warming is subject of public concern. The need to reduce the emissions of atmospheric green house gases and in particular carbon dioxide is greater than ever. Extensive research is performed to find new solutions and new materials, which tackles this problem in economically benign way. This thesis dealt with two potential adsorbents for post combustion  carbon capture, namely, amine modified silica and calcium carbonates. We modified porous silica with large surface area by propyl-amine groups to enhance the carbon dioxide adsorption capacity and selectivity. Experimental parameters, such as reaction time, temperature, water content, acid and heat treatment of silica substrate were optimized using a fractional factorial design. Adsorption properties and the nature of formed species upon reaction of CO2 and amine-modified silica were studied by sorption and infrared spectroscopy. Physisorbed and chemisorbed amount of adsorbed CO2 were, for the first time, estimated directly in an accurate way. The effects of temperature and moisture on the CO2 adsorption properties were also studied.

Crystallization of calcium carbonate as a precursor to calcium oxide, which can be used as carbon dioxide absorbent, was studied in the second part of this thesis. Structure of different amorphous phases of calcium carbonate was studied in detail. Crystallization of calcium carbonate with and without additives was studied. Parameters like stirring rate, temperature, pH and polymer concentration showed to be important in selection of phase and morphology. An aggregation mediated crystallization was postulated to explain the observed morphologies. 

Place, publisher, year, edition, pages
Stockholm: Department of Materials and Environmental Chemistry (MMK), Stockholm University, 2012. 87 p.
Keyword
Amine-modified silica, carbon capture, Fractional factorial design, IR spectroscopy, calcium carbonate
National Category
Materials Chemistry
Research subject
Materials Chemistry
Identifiers
urn:nbn:se:su:diva-75638 (URN)978-91-7447-516-6 (ISBN)
Public defence
2012-06-05, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 13:00 (English)
Opponent
Supervisors
Note
At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Accepted.Available from: 2012-05-10 Created: 2012-04-24 Last updated: 2012-04-30Bibliographically approved

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