The temperature dependence of the solubility product constant of vivianite

Al-Borno, Amal; Tomson, Mason B.

doi:10.1016/0016-7037(94)90236-4

Cited by 105 publications

(59 citation statements)

References 5 publications

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“…Estimating the thermodynamic properties of phosphate minerals 115 Wagman et al (1982), (2) Vieillard & Tardy (1984), (3) Wagman (1968), (4) Latimer (1952), (5) Parker et al (1971), (6) Naumov et al (1971), (7) Duff (1971a), (8) Rossini et al (1952), (9) Duff (1972), (10) Robie et al (1979), (11) Duff (1971b), (12) Tacker & Stormer (1989), (13) Al-Borno & Tomson (1994), (14) Woods & Garrels (1987). -3,783.85 -3,781.27 -3,708.57 -3,700.27 -3,633.63 -3,619.27 -3,559.16 -3,538.27 Ca 5 (P0 4 ) [3][4][5][6]928.26 Ca 5 (P0 4 ) 3 0H 763.91 (1) Robie et al (1979); (2) Calculated using values of Table 3.…”

Section: Resultsmentioning

confidence: 99%

Estimating the thermodynamic properties of phosphate minerals at high and low temperature from the sum of constituent units

Iglesia¹

2009

Estud. geol.

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Using the polyhedral units model of Hazen and employing a method of least-squares, the contribution of nineteen constituent units to the free energy and fifteen units to the enthalpy, at 298 K and 1 bar of pressure, have been calculated for mineral phosphates. The contribution of these constituent units to the free energy at higher temperatures has also been calculated.From these data we can estimate the thermodynamic properties of phosphates by summing the contribution of the distinct units, with more accuracy than the methods published up until now.

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Section: Resultsmentioning

confidence: 99%

Estimating the thermodynamic properties of phosphate minerals at high and low temperature from the sum of constituent units

Iglesia¹

2009

Estud. geol.

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“…First, the layer may have been disrupted under single bacteria or biofilm patches as a result of oxygen depletion, possibly enhanced by excretion products. Once small holes in the oxide layer were formed, corrosion of the underlying iron, according to the equation Fe ϩ 1 2 O 2 ϩ H 2 O3Fe(OH) 2 , could have added to the consumption of oxygen (28). The steel surface would now have consisted of two electrochemically different types of areas: a large area without biofilm coverage where E was still high and a smaller area with few biofilmcovered spots where E was already at E min .…”

Section: Discussionmentioning

confidence: 99%

Bacterial Phosphating of Mild (Unalloyed) Steel

Volkland

Harms

Müller

et al. 2000

Appl Environ Microbiol

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Mild (unalloyed) steel electrodes were incubated in phosphate-buffered cultures of aerobic, biofilm-forming Rhodococcus sp. strain C125 and Pseudomonas putida mt2. A resulting surface reaction leading to the formation of a corrosion-inhibiting vivianite layer was accompanied by a characteristic electrochemical potential (E) curve. First, E increased slightly due to the interaction of phosphate with the iron oxides covering the steel surface. Subsequently, E decreased rapidly and after 1 day reached ؊510 mV, the potential of free iron, indicating the removal of the iron oxides. At this point, only scattered patches of bacteria covered the surface. A surface reaction, in which iron was released and vivianite precipitated, started. E remained at ؊510 mV for about 2 days, during which the vivianite layer grew steadily. Thereafter, E increased markedly to the initial value, and the release of iron stopped. Changes in E and formation of vivianite were results of bacterial activity, with oxygen consumption by the biofilm being the driving force. These findings indicate that biofilms may protect steel surfaces and might be used as an alternative method to combat corrosion.Due to the poor corrosion resistance of mild (unalloyed) steel, virtually all items made of this material have to be protected against corrosion. The most common protection method is phosphating, i.e., coating the steel surface with the phosphates of zinc, iron, or manganese (34). This procedure is carried out at temperatures up to 95°C and pH values between 2 and 3.5 (21). Media used for phosphating normally contain high concentrations of zinc (in the range of several grams per liter) or manganese and also contain accelerators like nitrate, nitrite, chlorate, peroxides, and organic nitrocompounds (31). During phosphating, a considerable amount of heavy metal sludge is formed and must be removed. Several attempts have been made to develop alternative methods that are less toxic to the environment.Pedersen et al. (17) showed that Pseudomonas sp. strain S9 and Serratia marcescens sp. strain EF 190 can decrease the corrosion rate of mild steel when applied as dense suspensions (10 9 ml Ϫ1 ) or as living biofilms (17)(18)(19). A protective effect of Pseudomonas fragi and Escherichia coli DH5 was found by Jayaraman et al. (13). Here, the formation of a biofilm was crucial, as oxygen depletion under the biofilm was responsible for the corrosion protection (12). However, the mechanical instability of biofilms was seen as a drawback for their technical application.In a recent study (32), we showed that growing the aerobic biofilm-forming bacteria Rhodococcus sp. strain C125 and Pseudomonas putida mt2 in mineral medium containing more than 2 mM phosphate induced a surface reaction on mild steel coupons, resulting in the formation of vivianite. Vivianite, a barely insoluble iron(II) phosphate, is one of the compounds formed in technical acidic phosphating and is known for its corrosion protective effect. The biologically vivianite-coated steel coupons showed goo...

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“…In phosphate-rich reducing environments, vivianite (Fe 3 (PO 4 ) 2 Á8H 2 O) is an important sink for dissolved Fe(II) and is considered a stable mineral due to its low solubility at neutral pH (Nriagu and Dell, 1974;Buffle et al, 1989;Manning et al, 1991;Al-Borno and Tomson, 1994;Viollier et al, 1997;Sapota et al, 2006). Under anoxic conditions, vivianite is very stable (K sp = 10 À36 ; (Nriagu, 1972)) and can exert significant control over the geochemical cycles of Fe and P. Vivianite has also been reported as an end product of bacterial Fe(III) reduction Zachara et al, 1998;Roh et al, 2007;Peretyazhko et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Products of abiotic U(VI) reduction by biogenic magnetite and vivianite

Veeramani

Alessi

Suvorova

et al. 2011

Geochimica et Cosmochimica Acta

138

122

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Reductive immobilization of uranium by the stimulation of dissimilatory metal-reducing bacteria (DMRB) has been investigated as a remediation strategy for subsurface U(VI) contamination. In those environments, DMRB may utilize a variety of electron acceptors, such as ferric iron which can lead to the formation of reactive biogenic Fe(II) phases. These biogenic phases could potentially mediate abiotic U(VI) reduction. In this work, the DMRB Shewanella putrefaciens strain CN32 was used to synthesize two biogenic Fe(II)-bearing minerals: magnetite (a mixed Fe(II)-Fe(III) oxide) and vivianite (an Fe(II)-phosphate). Analysis of abiotic redox interactions between these biogenic minerals and U(VI) showed that both biogenic minerals reduced U(VI) completely. XAS analysis indicates significant differences in speciation of the reduced uranium after reaction with the two biogenic Fe(II)-bearing minerals. While biogenic magnetite favored the formation of structurally ordered, crystalline UO 2 , biogenic vivianite led to the formation of a monomeric U(IV) species lacking U-U associations in the corresponding EXAFS spectrum. To investigate the role of phosphate in the formation of monomeric U(IV) such as sorbed U(IV) species complexed by mineral surfaces, versus a U(IV) mineral, uranium was reduced by biogenic magnetite that was pre-sorbed with phosphate. XAS analysis of this sample also revealed the formation of monomeric U(IV) species suggesting that the presence of phosphate hinders formation of UO 2 . This work shows that U(VI) reduction products formed during in situ biostimulation can be influenced by the mineralogical and geochemical composition of the surrounding environment, as well as by the interfacial solute-solid chemistry of the solid-phase reductant.

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The temperature dependence of the solubility product constant of vivianite

Cited by 105 publications

References 5 publications

Estimating the thermodynamic properties of phosphate minerals at high and low temperature from the sum of constituent units

Estimating the thermodynamic properties of phosphate minerals at high and low temperature from the sum of constituent units

Bacterial Phosphating of Mild (Unalloyed) Steel

Products of abiotic U(VI) reduction by biogenic magnetite and vivianite

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