The role of carbonate ions in pyrite oxidation in aqueous systems

Caldeira, Claudia L.; Ciminelli, Virgínia S. T.; Osseo‐Asare, K.

doi:10.1016/j.gca.2009.12.014

Cited by 79 publications

(42 citation statements)

References 50 publications

(118 reference statements)

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“…This is supported by increases to Fe 2+ / Fe 3+ ratios in the 0.5 M HCl extractable fraction during anoxic conditions. Frequent rapid reoxidation of ferrous sulfide due to air sparging in the reactor experiment, and extensive in situ bioturbation, likely prevents formation of more recalcitrant and slow-forming iron sulfide minerals such as pyrite, despite strong thermodynamic favorability for pyrite formation (SI up to +13.13) (Caldeira et al, 2010;Peiffer et al, 2015). This is consistent with the results of XRD analysis, which did not identify pyrite (Fig.…”

Section: Fe : P Ratiossupporting

confidence: 85%

“…The kinetic constraints on precipitation were not, however, considered. No significant cumulative change to extractable Fe 2+ / Fe 3+ occurred after five full reduction-oxidation cycles, indicating that solid-phase Fe redox cycling was reversible, potentially due to rapid oxidation of solid Fe 2+ in the presence of O 2 and carbonate (Caldeira et al, 2010).…”

Section: Experimental Redox Oscillation: Aqueous Chemistrymentioning

confidence: 99%

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Sediment phosphorus speciation and mobility under dynamic redox conditions

Parsons¹,

Rezanezhad²,

O’Connell³

et al. 2017

Biogeosciences

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Abstract. Anthropogenic nutrient enrichment has caused phosphorus (P) accumulation in many freshwater sediments, raising concerns that internal loading from legacy P may delay the recovery of aquatic ecosystems suffering from eutrophication. Benthic recycling of P strongly depends on the redox regime within surficial sediment. In many shallow environments, redox conditions tend to be highly dynamic as a result of, among others, bioturbation by macrofauna, root activity, sediment resuspension and seasonal variations in bottom-water oxygen (O 2 ) concentrations. To gain insight into the mobility and biogeochemistry of P under fluctuating redox conditions, a suspension of sediment from a hypereutrophic freshwater marsh was exposed to alternating 7-day periods of purging with air and nitrogen gas (N 2 ), for a total duration of 74 days, in a bioreactor system. We present comprehensive data time series of bulk aqueous-and solidphase chemistry, solid-phase phosphorus speciation and hydrolytic enzyme activities demonstrating the mass balanced redistribution of P in sediment during redox cycling. Aqueous phosphate concentrations remained low (∼ 2.5 µM) under oxic conditions due to sorption to iron(III) oxyhydroxides. During anoxic periods, once nitrate was depleted, the reductive dissolution of iron(III) oxyhydroxides released P. However, only 4.5 % of the released P accumulated in solution while the rest was redistributed between the MgCl 2 and NaHCO 3 extractable fractions of the solid phase. Thus, under the short redox fluctuations imposed in the experiments, P remobilization to the aqueous phase remained relatively limited. Orthophosphate predominated at all times during the experiment in both the solid and aqueous phase. Combined P monoesters and diesters accounted for between 9 and 16 % of sediment particulate P. Phosphatase activities up to 2.4 mmol h −1 kg −1 indicated the potential for rapid mineralization of organic P (P o ), in particular during periods of aeration when the activity of phosphomonoesterases was 37 % higher than under N 2 sparging. The results emphasize that the magnitude and timing of internal P loading during periods of anoxia are dependent on both P redistribution within sediments and bottom-water nitrate concentrations.

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Section: Fe : P Ratiossupporting

confidence: 85%

Section: Experimental Redox Oscillation: Aqueous Chemistrymentioning

confidence: 99%

Sediment phosphorus speciation and mobility under dynamic redox conditions

Parsons¹,

Rezanezhad²,

O’Connell³

et al. 2017

Biogeosciences

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“…We focus our attention on pyrite since we expect it to be much more chemically active than the other major minerals, siderite and ankerite. Our review of the literature indicates that the surface of pyrite can undergo oxidation under either acidic or basic conditions and that, with oxygen in a high-pH medium (sodium carbonate at pH 10-11), the result is a coating on the pyrite of a group of amorphous iron oxides that appears to include ferrihydrite as the main constituent, possibly also with ferrous hydroxyl carbonate (Caldeira et al, 2003, Caldeira et al, 2010. Given that the dithionite mixture has been used for removal of oxidized iron species, especially amorphous materials, we would anticipate that it would have the same effect on the amorphous iron oxides on the surface of pyrite.…”

Section: Introductionmentioning

confidence: 99%

Restoration of Reservoir Cores to Reservoir Condition before Chemical Flooding Tests

et al. 2014

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Chemical EOR can be a very efficient enhanced oil recovery method when properly designed, but specialized laboratory tests must be done to tailor it to the specific reservoir fluids and mineralogy. The final step in the laboratory evaluation process is to test the chemicals in reservoir cores under reservoir conditions. Unfortunately, available reservoir cores are typically not in their native state. In particular, they are usually in a highly oxidized state (high E h ) compared to the reservoir formation. The oxidation state of the minerals affects the surfactants and polymers used for chemical EOR. In particular, at high E h some of the iron-containing minerals may have surficial ferric ions that were originally ferrous under the low E h conditions in the reservoir. Ferric ions can cause polymer degradation, poor polymer transport, and increased surfactant adsorption to the matrix, among other problems contributing to lower oil recovery. In general, to obtain valid test results, such cores must be restored to reservoir conditions to ensure valid results from core floods. We have investigated methods suitable for removing these ferric ions and restoring the core to reservoir condition. The new restoration method described in this paper dramatically improved polymer transport, reduced polymer and surfactant retention, and improved the oil recovery performance by the chemicals in several core floods. It should also be considered for other types of core floods to avoid getting laboratory results that are not representative of the behavior in the actual reservoir, which is in a reduced oxidation state compared to old cores.

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“…There have been extensive studies of the rate and mechanism of pyrite oxidation due to its importance in the mining industry (in mineral processing, metal extraction, and acid mine drainage). The situation is complex and the process is dependent on temperature and pH.…”

Section: Resultsmentioning

confidence: 99%

The Application of Ionic Nanoparticles in the Conservation of Archaelogical Wood

Chadwick

Howland

Went

et al. 2014

Macromolecular Symposia

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Summary A potential method for the de‐acidification of water‐logged archaeological wood is through a treatment with alkaline nanoparticles. In previous studies, we have shown that strontium carbonate nanoparticles are especially effective in removing sulfuric acid from the Mary Rose timbers. In this contribution, we report the effect of these nanoparticles on other known sulfur compounds in the timbers. Overall, these effects are beneficial, yielding benign compounds and removing the possibility for the conversion to sulfuric acid.

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The role of carbonate ions in pyrite oxidation in aqueous systems

Cited by 79 publications

References 50 publications

Sediment phosphorus speciation and mobility under dynamic redox conditions

Sediment phosphorus speciation and mobility under dynamic redox conditions

Restoration of Reservoir Cores to Reservoir Condition before Chemical Flooding Tests

The Application of Ionic Nanoparticles in the Conservation of Archaelogical Wood

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