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conferenceseries
.com
September 02-03, 2019 | Berlin, Germany
6
th
World Conference on Climate Change
Volume 10
Journal of Earth Science & Climatic Change
ISSN: 2157-7617
Climate Change 2019
September 02-03, 2019
Mineralization of CO
2
for Carbon Sequestration using Flue Gas Desulphurization Gypsum
Jonathan Riddle
and
Rona J. Donahoe
The University of Alabama, USA
P
ast efforts for carbon sequestration using CO
2
mineralization have proven effective for long-term stable storage of
CO
2
but were prohibitive due to slow reaction rates and high cost. Recent mineralization studies reacting flue gas
desulphurization (FGD) gypsum (CaSO
4
•2H
2
O) with CO
2
in an alkaline solution, have shown conversion of gypsum
into calcium carbonate (CaCO
3
) to be a rapid and effective method for carbon sequestration. However, these studies
used sodium hydroxide and ammonia to increase solution pH. The use of ammonia makes this mineralization
method inefficient due to the production of ammonia being a significant CO
2
source. The goal of this study was to
obtain high FGD gypsum-to-calcite conversation percentages at ambient temperature while eliminating the need for
ammonia. A stirred reactor was utilized to study the effects of P
CO2
(10, 30, 60, and 250 psi), solution pH (12, 13, 13.5
and 14), solid-to-solution ratio (1:100, 1:80, 1:40, 1:100), and reaction time (10, 15, 30, and 120+ minutes) variation
on the rate of conversion. The amount of carbonate produced was calculated from Rietveld refinement of XRD
patterns to determine the impact of each variable. Experimental results showed varying degrees of FGD gypsum
to CaCO
3
conversion. Solution pH was a primary control on conversion rates, with complete conversion occurring
under all conditions at pH 13.5 and 14. Time also played a significant role in conversion rates, from 0% conversion
at pH 13 after 360 minutes of reaction time, to approximately 75% conversion at pH 13 after 15 minutes of reaction
time. The most cost-effective conversions took place at low P
CO2
(10 psi), pH 13 and a reaction time of 15 minutes,
with a conversion rate of around 75%. The results of this study demonstrate that FGD gypsum can serve as a viable
feedstock for CO
2
mineralization, potentially providing an inexpensive method for carbon sequestration.
Biography
Jonathan Riddle received a bachelor’s degree in science at the University of North Alabama. After receiving his degree, he took a hiatus of four years to teach
English in Japan. Afterwards, he decided to continue his geologic career and is currently a master’s student at the University of Alabama. He began studying
environmental issues and was awarded the Outstanding Research Paper from Geosyntec in 2018. He has been working with his professor, Dr. Rona Donahoe,
on carbon mineralization. His is currently investigating more effective ways to use flue gas desulphurization gypsum for CO
2
sequestration. He will be finishing
his master’s degree in December of this year in environmental geochemistry.
Jonathan Riddle et al., J Earth Sci Clim Change 2019, Volume: 10