Heterogeneous electron transfer as a pathway in the dissolution of magnetite in oxalic acid solutions

Baumgartner, Erwin; Blesa, Miguel A.; Marinovich, H. A.; Maroto, A. J. G.

doi:10.1021/ic00158a002

Cited by 88 publications

(54 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Because the Fe2+-O bond is longer than the Fe3+-O bond, ferrous ions leave the structure more readily than do ferric ions, which accounts for the greater speed ofreductive dissolution. Autocatalytic dissolution has been observed for magnetite and hematite in de-aerated oxalic acid solutions (Segal and Sellars, 1984;Baumgartner et al, 1983). In both investigations, the shape of the kinetic curve was attributed to accelerated dissolution promoted by adsorbed ferrous oxalate.…”

Section: Discussionmentioning

confidence: 89%

“…It is also a component of the oxalic acid/ammonium oxalate solution that is widely used by soil scientists to dissolve noncrystalline iron oxides from mixtures of noncrystalline and crystalline oxides (Schwertmann, 1964). Several investigations have established the mechanism by which iron oxides dissolve in oxalic acid in the absence of light (DeEndreddy, 1963;Baumgartner et aL, 1983;Segal and Sellars, 1984;Zinder et aL, 1986;Miller et al, 1986). Although ultraviolet light has been shown to accelerate the reaction, the mechanism involved has not been fully established (DeEndreddy, 1963).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Photochemical Dissolution of Goethite in Acid/Oxalate Solution

Cornell

1987

Clays and clay miner.

128

View full text Add to dashboard Cite

Abstract--During photochemical dissolution of goethite in acid/oxalate solution, Fe 3+, Fe 2+, and CO2 were released and towards the end of the reaction ferrous oxalate precipitated. The dissolution process involved an initial stow stage followed by a much faster reaction. The slow stage was eliminated by addition of 20 ppm Fe z+ to the system at the start of the reaction. The presence of this Fe 2+ did not accelerate the secondary dissolution process. Both protons and oxalate ions appear to have been involved in the dissolution process. Dissolution was accelerated by an increase in oxalate concentration (from 0.0025 to 0.025 M) in the system and also depended on pH, reaching a maximum rate at pH 2.6. Highly substituted (15.9 mole % AI) goethite dissolved more slowly per unit area than unsubstituted goethite. Lepidocrocite (7-FeOOH) dissolved faster than goethite. The first stage of the dissolution process probably proceeded by slow release of Fe 3 § through complexation with oxalate adsorbed on the goethite surface. The faster, secondary step appears to have been a reductive dissolution reaction involving adsorbed ferrous oxalate.

show abstract

Section: Discussionmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Photochemical Dissolution of Goethite in Acid/Oxalate Solution

Cornell

1987

Clays and clay miner.

128

View full text Add to dashboard Cite

show abstract

“…This process is of importance to fields as diverse as environmental chemistry (Sulzberger et al, 1989;Schwertmann, 1991) and geochemical exploration (Sidhu et al, 1981). Acid and ligand dissolution of Fe-oxides such as magnetite and hematite has also been studied in relation to the descaling of reactor cooling pipes (Segal and Sellers, 1981;Baumgartner et al, 1983).…”

Section: Introductionmentioning

confidence: 99%

Properties and Acid Dissolution of Metal-Substituted Hematites

Wells

Gilkes

Fitzpatrick

2001

Clays and clay miner.

View full text Add to dashboard Cite

Abstract--The dissolution in 1 M HC1 of AI-, Mn-, and Ni-substituted hematites and the influence of metal substitution on dissolution rate and kinetics of dissolution were investigated. The inhomogeneous dissolution of most of the hematites investigated was well described by the Avrami-Erofe'ev rate equation, kt = ~/[-ln(1 -a)], where k is the dissolution rate in time, t, and ct is the Fe dissolved. Dissolution of Al-substituted hematite occurred mostly by edge attack and hole formation normal to (001), with the rate of dissolution, k, directly related to surface area (SA). Dissolution of rhombohedral Mn-and Ni-bearing hematites occurred at domain boundaries, crystal edges, and corners with k unrelated to SA. The morphology of Mn-and Ni-substituted hematites changed during dissolution with clover-leaf-like forms developing as dissolution proceeded, whereas the original plate-like morphology of Al-bearing hematite was generally retained. Acid attack of platy and rhomboidal hematite is influenced by the direct (e.g., metaloxygen bond energy, hematite crystallinity) and indirect (e.g., crystal size and shape) affects associated with incorporation of foreign ions within hematite.

show abstract

“…The dissolution chemistry of the major metal oxides present in sludge heels (Fe, Al, U, Mn) has been well characterized in the scientific literature with respect to the mechanism and kinetics of the dissolution. 11,[94][95][96][97][98][99][100][101][102] Iron oxide dissolution (hematite and magnetite) in oxalic acid has been the focus of a large amount of research due to the impact of corrosion products on boilers or other metal parts in contact with moisture in the industrial sector. The dissolution of iron shows a dependency on acid concentration, pH, and temperature.…”

Section: General Discussion On the Literature Reviewmentioning

confidence: 99%

Review of Alternative Enhanced Chemical Cleaning Options for SRS Waste Tanks

Hay¹,

Koopman²

2009

View full text Add to dashboard Cite

Heterogeneous electron transfer as a pathway in the dissolution of magnetite in oxalic acid solutions

Cited by 88 publications

References 0 publications

Photochemical Dissolution of Goethite in Acid/Oxalate Solution

Photochemical Dissolution of Goethite in Acid/Oxalate Solution

Properties and Acid Dissolution of Metal-Substituted Hematites

Review of Alternative Enhanced Chemical Cleaning Options for SRS Waste Tanks

Contact Info

Product

Resources

About