Computer Simulations Indicate Calcium Carbonate Has a Dense Liquid Phase (http://newscenter.lbl.gov/news-releases/2013/08/22/calcium-carbonate/)
Computer simulations conducted at the
Calcium carbonate is a huge player in the planet's carbon cycle, so any new insight into how it behaves is potentially big news. The prediction of a dense liquid phase during the conversion of calcium carbonate to a solid could help scientists understand the response of marine organisms to changes in seawaterchemistrydue to rising atmospheric CO2 levels. It could also help them predict the extent to which geological formations can act as carbon storage reservoirs, among other examples.
The research is published in the
The research may also reconcile some confounding experimental observations. For more than a century, scientists believed that crystals nucleate from solution by overcoming an energy barrier. But recent studies of calcium carbonate revealed the presence of nanoscopic clusters which, under certain conditions, appear to circumvent the barrier by following an alternative aggregation-based crystallization pathway.
"Because nucleation is ubiquitous in both natural and synthetic systems, those findings have forced diverse scientific communities to reevaluate their longstanding view of this process," says the study's co-corresponding author
The findings support the aggregation-based mechanism of calcium carbonate formation. They also indicate that the presence of the nanoscale phase is consistent with a process called liquid-liquid separation, which is well known in alloys and polymers, but unexpected for salt solutions.
"Our simulations suggest the existence of a dense liquid form of calcium carbonate," says co-corresponding author
"This is important because it is an as-yet unappreciated component of the carbon cycle," adds Wallace. "It also provides a means of explaining the unusual presence of nanoscale clusters in solution within the context of established physical mechanisms."
This research was supported by the U.S.
The Molecular Foundry is one of five DOE Nanoscale Science Research Centers (NSRCs), national user facilities for interdisciplinary research at the nanoscale, supported by the
The research, "Microscopic Evidence for Liquid-Liquid Separation in Supersaturated CaCO3 Solutions" is published in the
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