Mineral carbon dioxide sequestration binds CO2 by reacting it with calcium or magnesium silicate minerals to form solid magnesium or calcium carbonate products that are ready for disposal. The development of a cost effective process would provide a powerful tool in carbon management.
Research on mineral sequestration has focused on enhancing process kinetics in aqueous processing schemes. High costs of these processes are associated with mineral processing, such as ultrafine grinding steps, or the consumption of acids and bases, required to speed up silicate mineral dissolution kinetics.
Through experimental work neutral organic salts such as sodium oxalate, and sodium citrate, are identified as potential catalysts for use in enhancing dissolution kinetics without being consumed in the reaction. Neutral salts NaCl, NH4Cl, and sodium acetate are shown to be ineffective. The dissolution rate of antigorite serpentine is shown to have concentration dependence of order 0.52 and activation energy of dissolution of 38.3 kJ/mol in the presence of the citrate ion under weakly acidic conditions. Rates are shown to be several orders of magnitude higher in the presence of citrate than in the weakly acidic solution alone.
The 2005 Intergovernmental Panel on Climate Change report on Carbon Dioxide Capture and Storage suggested that a major gap in mineral CO2 sequestration is locating the magnesium-silicate bedrock available to sequester the carbon dioxide. Researchers at Columbia University and the U.S. Geological Survey have developed a digital geologic database of ultramafic rocks in the conterminous United States. Data were compiled from varied-scale geologic maps of magnesium-silicate ultramafic rocks. The focus of our national-scale map is entirely on ultramafic rock types, which typically consist primarily of olivine- and serpentine-rich rocks. These rock types are potentially suitable as source material for mineral CO2 sequestration.
Simple estimates are made on the potential for CO2 storage capacity. Using simplifying assumptions on the depth of mines, the efficiency of conversion, and the magnesium concentration of the rock, it is shown that a conservative surface area specific sequestration capacity range for ultramafic rocks is 50-80 Mt CO2 per km2 of ultramafic rock exposure. There is over 16,000 km2 of ultramafic rock exposure in the conterminous United States, about 4,000 km2 of which lies in urban areas and federal lands such as national parks that exclude the possibility of mining. Thus the sequestration capacity of ultramafic rocks in the conterminous United States can reasonably believed to be at least 600-960 Gt CO2.
|Advisor:||Lackner, Klaus S.|
|School Location:||United States -- New York|
|Source:||DAI-B 70/02, Dissertation Abstracts International|
|Subjects:||Environmental science, Environmental engineering|
|Keywords:||Carbon sequestration, Mineral sequestration, Serpentine, Silicate dissolution, Ultramafic rocks|
Copyright in each Dissertation and Thesis is retained by the author. All Rights Reserved
The supplemental file or files you are about to download were provided to ProQuest by the author as part of a
dissertation or thesis. The supplemental files are provided "AS IS" without warranty. ProQuest is not responsible for the
content, format or impact on the supplemental file(s) on our system. in some cases, the file type may be unknown or
may be a .exe file. We recommend caution as you open such files.
Copyright of the original materials contained in the supplemental file is retained by the author and your access to the
supplemental files is subject to the ProQuest Terms and Conditions of use.
Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be