Thermodynamic Controls on the Kinetics of Microbial Low-pH Fe(II) Oxidation
| Autor: | Bradley Kaley, Javier Sánchez-España, Lance N. Larson, William D. Burgos, Kyle Bibby, Yizhi Sheng |
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| Rok vydání: | 2014 |
| Předmět: |
Appalachian Region
Iberian Pyrite Belt Chemistry Iron Kinetics Industrial Waste Mineralogy General Chemistry Hydrogen-Ion Concentration Acid mine drainage Mining Gibbs free energy symbols.namesake Spain Coal basin Environmental chemistry symbols Bioreactor Thermodynamics Environmental Chemistry Groundwater quality Oxidation-Reduction |
| Zdroj: | Environmental Science & Technology. 48:9246-9254 |
| ISSN: | 1520-5851 0013-936X |
| DOI: | 10.1021/es501322d |
| Popis: | Acid mine drainage (AMD) is a major worldwide environmental threat to surface and groundwater quality. Microbial low-pH Fe(II) oxidation could be exploited for cost-effective AMD treatment; however, its use is limited because of uncertainties associated with its rate and ability to remove Fe from solution. We developed a thermodynamic-based framework to evaluate the kinetics of low-pH Fe(II) oxidation. We measured the kinetics of low-pH Fe(II) oxidation at five sites in the Appalachian Coal Basin in the US and three sites in the Iberian Pyrite Belt in Spain and found that the fastest rates of Fe(II) oxidation occurred at the sites with the lowest pH values. Thermodynamic calculations showed that the Gibbs free energy of Fe(II) oxidation (ΔG(oxidation)) was also most negative at the sites with the lowest pH values. We then conducted two series of microbial Fe(II) oxidation experiments in laboratory-scale chemostatic bioreactors operated through a series of pH values (2.1-4.2) and found the same relationships between Fe(II) oxidation kinetics, ΔG(oxidation), and pH. Conditions that favored the fastest rates of Fe(II) oxidation coincided with higher Fe(III) solubility. The solubility of Fe(III) minerals, thus plays an important role on Fe(II) oxidation kinetics. Methods to incorporate microbial low-pH Fe(II) oxidation into active and passive AMD treatment systems are discussed in the context of these findings. This study presents a simplified model that describes the relationship between free energy and microbial kinetics and should be broadly applicable to many biogeochemical systems. |
| Databáze: | OpenAIRE |
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