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Title: Muscovite dissolution kinetics as a function of pH at elevated temperature

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Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 0009-2541
Grant/Contract Number:
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Chemical Geology
Additional Journal Information:
Journal Volume: 466; Journal Issue: C; Journal ID: ISSN 0009-2541
Country of Publication:
United States

Citation Formats

Lammers, Kristin, Smith, Megan M., and Carroll, Susan A.. Muscovite dissolution kinetics as a function of pH at elevated temperature. United States: N. p., 2017. Web. doi:10.1016/j.chemgeo.2017.06.003.
Lammers, Kristin, Smith, Megan M., & Carroll, Susan A.. Muscovite dissolution kinetics as a function of pH at elevated temperature. United States. doi:10.1016/j.chemgeo.2017.06.003.
Lammers, Kristin, Smith, Megan M., and Carroll, Susan A.. 2017. "Muscovite dissolution kinetics as a function of pH at elevated temperature". United States. doi:10.1016/j.chemgeo.2017.06.003.
title = {Muscovite dissolution kinetics as a function of pH at elevated temperature},
author = {Lammers, Kristin and Smith, Megan M. and Carroll, Susan A.},
abstractNote = {},
doi = {10.1016/j.chemgeo.2017.06.003},
journal = {Chemical Geology},
number = C,
volume = 466,
place = {United States},
year = 2017,
month = 9

Journal Article:
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  • Experiments were carried out in a 1-5 M potassium hydroxide solutions in the current density range 0.3-3.0 A/m/sup 2/. Time vs. potential curves were recorded with a flat electrode of Armco iron previously annealed in an atmosphere of hydrogen. Typical electrostatic curves obtained on the smooth iron electrode at various densities were presented, and the cathodic potentio-dynamic curves measured in a 4.1 M potassium hydroxide solution on electrodes which had been previously oxidized at different current densities are shown. It was shown that the equation presented encompasses the time vs. potential diagrams obtained at both 25 C and 50 C,more » which was indicative of a single mechanism for anodic oxidation in that temperature interval.« less
  • The authors have measured the dissolution rate of diopside in dilute solutions (far from equilibrium) at 25, 50, and 70[degrees]C from pH 2 through pH 12 using a flow-through reactor. Reducing the CO[sub 2] concentration tenfold produced little, if any, effect on dissolution rate at alkaline pH (pH 8 through pH 12) at 25 and 70[degrees]C. Linear dissolution kinetics (i.e., time-invariant rates) were eventually observed in all runs. The overall trend with increasing pH is decreasing diopside dissolution rate based on the release rate of all constituents. The authors fit these rates by regression to a general rate law ofmore » the form r = Ak[[alpha][sub H[sup +]]][sup n], where A is the surface area, k is the rate constant, and n is the order with respect to hydrogen ion activity. At 70[degrees]C over the range pH 2 through pH 10 in solutions equilibrated with atmospheric CO[sub 2], the rate of diopside dissolution based on Si release is rate (mol/cm[sup 2]-s) = 2.45 ([plus minus]0.96)[times]10[sup [minus]13] [alpha][sub H[sup +]][sup 0.18[plus minus]0.03]. At 50[degrees]C the rate based on Si release is rate (mol/cm[sup 2]-s) = 1.10([plus minus]0.61)[times]10[sup [minus]13] [alpha][sub H[sup +]][sup 0.21[plus minus]]0.04. At 25[degrees]C the rate based on Si release is rate (mol/cm[sup 2]-s) = 2.88([plus minus]1.33)[times]10[sup [minus]14] [alpha][sub H[sup +]][sup 0.18[plus minus]0.03]. Based on a regression of the rate constants, over the temperature interval 25 to 70[degrees]C, the activation energy for the dissolution of diopside is 9.7 [plus minus] 0.4 kcal/mol. This energy is indicative of a surface-reaction controlled dissolution process, as is the observation of crystallographically controlled etch pits. 31 refs., 5 figs., 5 tabs.« less
  • A single-pass, flow-through apparatus was used to determine the dissolution rate of quartz at 70{sup 0}C as a function of pH and time. Dissolution rate data were obtained over the pH range 1.4 to 11.8 in nine separate experiments each lasting 50 days. The quartz dissolution rates were defined by the silica release rate to solution. Speciation-solubility calculations using the geochemical modeling code EQ36 indicate that the fluid was maintained far from equilibrium with respect to quartz and well-undersaturated with respect to all possible secondary minerals in all runs. The dissolution rates were independent of pH at values (10/sup -15.3/more » molcm{sup 2} x s) consistent with the data of Rimstidt and Barnes (1980) up to approximately pH 6, but at higher pH the rates increased with increasing pH, proportional to a/sub H{sup +}//sup -0.5/, being almost four orders of magnitude higher at pH 11.8. The rate constants for quartz dissolution at 70{sup 0}C were 10/sup -15.3/ molcm{sup 2} x s in the pH-independent region extending from acid through neutral solutions, and 10/sup -17.8/ molcm{sup 2} x s in more alkaline solutions. Etch pits were strongly developed in the runs with the more alkaline solutions (pH > 8), in which the rates were the highest. This appears consistent with a surface reaction-controlled dissolution mechanism.« less
  • Of importance to geothermal energy development, oil, gas and mineral recovery, and waste storage is the characterization of the dissolution rate of host reservoir rock as a function of temperature, pressure and liquid-phase composition. As a major constitutive mineral in natural geologic systems, quartz was selected for study. Dissolution experiments were carried out in a continuous-flow, titanium autoclave reactor system at 100--200 C in various chemical environments. Acidification to pH 1.1 using nitric acid showed very little effect on the quartz dissolution rate. The effect of hydroxide ion concentration and ionic strength were evaluated in NaOH, NaOH/NaCl and NaOH/Na{sub 2}SO{submore » 4} solutions. The fractional-order dependency of the quartz dissolution rate on hydroxide ion and sodium ion (or ionic strength) concentration was determined in NaOH/NaCl solutions. The results that extend the available range of kinetic data for quartz generally agree with previous work. The observed fractional-order kinetics were qualitatively described using classical adsorption isotherms. No significant variation in the apparent reaction order of the hydroxide ion with increasing temperature could be determined due to the scatter in the data. Quartz dissolution rates were slower by about 40% in NaOH/Na{sub 2}SO{sub 4} solutions than in NaOH/NaCl solutions at sodium concentrations higher than 0.01 molal. The apparent activation energy from 100 to 200 C in NaOH/NaCl solutions up to 0.01 molal hydroxide ion and 0.1 molal sodium ion was estimated to be 72 ({+-}6) kJ/mol.« less