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Title

Lizardite serpentine dissolution kinetics as a function of pH and temperature, including effects of elevated pCO(2)

Publication Year

2013

Author(s)
  • Daval, Damien
  • Hellmann, Roland
  • Martinez, Isabelle
  • Gangloff, Sophie
  • Guyot, Francois
Source
CHEMICAL GEOLOGY Volume: 351 Pages: 245-256 Published: 2013
ISSN
0009-2541
Abstract

Measurements of the dissolution rate of lizardite (r) were carried out as a function of pH (2.5 <= pH <= 6.7) and temperature (27 degrees C <= T <= 90 degrees C) in continuously stirred flow-through systems, either in liquid-filled reactors or in aqueous solutions equilibrated with a headspace of gaseous CO2 (4 MPa <= pCO(2) <= 6 MPa). For the whole dataset, the stoichiometty of the reaction was highly correlated with the extent of Mg release, and congruent reactions were observed for the whole pH range only at T = 90 degrees C. Far from equilibrium, dissolution rates in dilute HCl solutions based on Si release and normalized to BET surface area can be described by: r = k(0) exp(-E-a/RT)a(H+)(n) with k(0) = 10(-2.27 +/- 0.56) mol.m(-2).s(-1); E-a = 42.0 +/- 1.5 kJ.mol(-1); R is the gas constant, n = 0.53 +/- 0.08. Moreover, in the pH range 3.2-6.2, the concentration of protons at the lizardite surface is proportional to a(H+)(0.47), which suggests that the dissolution rate has a first-order dependence on the surface concentration of protons. When the reaction was initiated in solutions equilibrated with elevated pCO(2), a slight increase of the dissolution rate (up to a 5-fold factor at pH = 5.0) was observed with respect to CO2-free solutions at the same pH. This may be attributed to the rate enhancing effect of HCO3- ligands. For any single pH-T condition investigated in the present study, lizardite dissolution rates are orders of magnitude lower than those of other anhydrous basic silicates, such as olivine or pyroxenes. The sluggishness of the dissolution reaction probably explains the slow carbonation rates that have been measured in previous studies. Crown Copyright (c) 2013 Published by Elsevier B.V. All rights reserved.

Author Keyword(s)
  • Serpentine
  • Dissolution rate laws
  • CO2 sequestration
  • Hydrothermal fluids
  • Phyllosilicates
  • Weathering
KeyWord(s) Plus
  • SOLUTION SATURATION STATE
  • ALBITE-WATER SYSTEM
  • FORSTERITE DISSOLUTION
  • OLIVINE DISSOLUTION
  • MINERAL CARBONATION
  • PRECIPITATION KINETICS
  • KAOLINITE DISSOLUTION
  • CHRYSOTILE ASBESTOS
  • CO2 SEQUESTRATION
  • SILICATE MINERALS
ESI Discipline(s)
  • Geosciences
Web of Science Category(ies)
  • Geochemistry & Geophysics
Adress(es)

[Daval, Damien; Martinez, Isabelle; Guyot, Francois] Ctr Rech Stockage Geol CO2, Inst Phys Globe Paris, F-75238 Paris 05, France; [Daval, Damien; Gangloff, Sophie] Univ Strasbourg, Lab Hydrol & Geochim Strasbourg, CNRS, EOST,UMR 7517, F-67084 Strasbourg, France; [Hellmann, Roland] Univ Grenoble 1, Inst Sci Terre, CNRS, UMR C5275,OSUG, F-38041 Grenoble 9, France; [Guyot, Francois] Univ Paris 06, Inst Mineral & Phys Milieux Condenses, CNRS, F-75005 Paris, France; [Guyot, Francois] Univ Paris 07, Inst Mineral & Phys Milieux Condenses, CNRS, F-75005 Paris, France

Reprint Adress

Daval, D (reprint author), Univ Strasbourg, Lab Hydrol & Geochim Strasbourg, CNRS, EOST,UMR 7517, 1 Rue Blessig, F-67084 Strasbourg, France.

Country(ies)
  • France
CNRS - Adress(es)
  • Ecole et Observatoire des sciences de la Terre (EOST), UMS830
  • Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), UMR7590
  • Institut de Physique du Globe de Paris (IPGP), UMR7154
  • Institut des Sciences de la Terre (ISTerre), UMR5275
  • Laboratoire d'Hydrologie et de Géochimie de Strasbourg (LHyGeS), UMR7517
  • Observatoire des Sciences de l'Univers de Grenoble (OSUG), UMS832
Accession Number
WOS:000322857500019
uid:/WDXXFQPD
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