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Biologically enhanced degassing and precipitation of magnesium carbonates derived from bicarbonate solutions
Journal article   Peer reviewed

Biologically enhanced degassing and precipitation of magnesium carbonates derived from bicarbonate solutions

T.K. Oliver, B.Z. Dlugogorski and E.M. Kennedy
Minerals Engineering, Vol.61, pp.113-120
2014
DOI: https://doi.org/10.1016/j.mineng.2013.11.003
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Abstract

This contribution reports the results of batch and semibatch experiments involving bubbling of nitrogen in aqueous solutions of magnesium bicarbonate, with and without the addition of either carbonic anhydrase (CA) or Scenedesmus alga to the solution. Precipitation of nesquehonite occurred during both an accelerated degassing of CO2 induced by sparging small nitrogen bubbles (representative diameter of 20 μm), and during slow degassing engendered by introducing large nitrogen bubbles (representative diameter of 5 mm). The response of the system during low rates of degassing closely approached quasi-thermodynamic predictions, which permitted an estimation of the level of supersaturation of nesquehonite, prior to the onset of precipitation. Small bubbles and CA significantly increased rates of degassing and indirectly the production of nesquehonite, as the rate of degassing can limit the precipitation process. The response of the system during rapid rates of degassing, prior to precipitation, was not entirely consistent with quasi-thermodynamic predictions. During precipitation, higher rates of degassing produced similar alkalisation and precipitation trends to that observed for lower rates of degassing. Our results agree with the formation of travertine deposits in nature, where the degassing of solutions enriched with inorganic carbon, and enhanced alkalisation by microorganisms, have been shown to influence carbonate formation. The results demonstrate a catalytic effect of CA on the rate limiting carbonate reactions, increasing CO2 exchange between nitrogen and water, and indirectly accelerating the precipitation of carbonates for a system controlled by rate of degassing. The results of this study have applications to large-scale storage of CO2 by mineralisation.

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Collaboration types
Domestic collaboration
Citation topics
2 Chemistry
2.165 Nanofibers, Scaffolds & Fabrication
2.165.1082 Calcium Carbonate Crystallization
Web Of Science research areas
Engineering, Chemical
Mineralogy
Mining & Mineral Processing
ESI research areas
Geosciences
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