Rates of feldspar dissolution at pH 3-7 with 0-8 m M oxalic acid

Lisa L. Stillings, James I. Drever, Susan Louise Brantley, Yanting Sun, Rachael Oxburgh

Research output: Contribution to journalArticle

145 Citations (Scopus)

Abstract

Feldspar dissolution rates were measured in flow-through reactors, over a pH range of 3-7, oxalic acid concentration of 0-8 m M, and feldspar compositional range of An0-An76. Dissolution rates in O and l m M concentrations of oxalic acid increased linearly with increasing mole percent anorthite in the solid. Dissolution was nonstoichiometric in oxalic acid, due to a preferential release of Al at steady state, 1 m M concentrations of oxalic acid increased dissolution rates by a factor of 2-5 at pH 3 and 2-15 at pH 5-6. At pH 5-6 the rate enhancement due to oxalic acid may increase with increasing anorthite content of the feldspar. The ligand-promoted rate, RL, defined as the observed total rate in oxalic acid minus the proton-promoted rate, Rt - RH, was estimated as 10-12.8(aHOx-+ aOx2)0.75, suggesting that both HC2O-4 (bioxalate) and C2O2-4 (oxalate) play a role in the dissolution mechanism.

Original languageEnglish (US)
Pages (from-to)79-89
Number of pages11
JournalChemical Geology
Volume132
Issue number1-4 SPEC. ISS.
StatePublished - Oct 30 1996

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Oxalic Acid
oxalic acid
feldspar
Dissolution
dissolution
anorthite
Oxalates
oxalate
rate
Protons
ligand
Ligands

All Science Journal Classification (ASJC) codes

  • Geology
  • Geochemistry and Petrology

Cite this

Stillings, L. L., Drever, J. I., Brantley, S. L., Sun, Y., & Oxburgh, R. (1996). Rates of feldspar dissolution at pH 3-7 with 0-8 m M oxalic acid. Chemical Geology, 132(1-4 SPEC. ISS.), 79-89.
Stillings, Lisa L. ; Drever, James I. ; Brantley, Susan Louise ; Sun, Yanting ; Oxburgh, Rachael. / Rates of feldspar dissolution at pH 3-7 with 0-8 m M oxalic acid. In: Chemical Geology. 1996 ; Vol. 132, No. 1-4 SPEC. ISS. pp. 79-89.
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Stillings, LL, Drever, JI, Brantley, SL, Sun, Y & Oxburgh, R 1996, 'Rates of feldspar dissolution at pH 3-7 with 0-8 m M oxalic acid', Chemical Geology, vol. 132, no. 1-4 SPEC. ISS., pp. 79-89.

Rates of feldspar dissolution at pH 3-7 with 0-8 m M oxalic acid. / Stillings, Lisa L.; Drever, James I.; Brantley, Susan Louise; Sun, Yanting; Oxburgh, Rachael.

In: Chemical Geology, Vol. 132, No. 1-4 SPEC. ISS., 30.10.1996, p. 79-89.

Research output: Contribution to journalArticle

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AU - Drever, James I.

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N2 - Feldspar dissolution rates were measured in flow-through reactors, over a pH range of 3-7, oxalic acid concentration of 0-8 m M, and feldspar compositional range of An0-An76. Dissolution rates in O and l m M concentrations of oxalic acid increased linearly with increasing mole percent anorthite in the solid. Dissolution was nonstoichiometric in oxalic acid, due to a preferential release of Al at steady state, 1 m M concentrations of oxalic acid increased dissolution rates by a factor of 2-5 at pH 3 and 2-15 at pH 5-6. At pH 5-6 the rate enhancement due to oxalic acid may increase with increasing anorthite content of the feldspar. The ligand-promoted rate, RL, defined as the observed total rate in oxalic acid minus the proton-promoted rate, Rt - RH, was estimated as 10-12.8(aHOx-+ aOx2)0.75, suggesting that both HC2O-4 (bioxalate) and C2O2-4 (oxalate) play a role in the dissolution mechanism.

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Stillings LL, Drever JI, Brantley SL, Sun Y, Oxburgh R. Rates of feldspar dissolution at pH 3-7 with 0-8 m M oxalic acid. Chemical Geology. 1996 Oct 30;132(1-4 SPEC. ISS.):79-89.