Alteration kinetics of basaltic glass in acidic conditions: The effect of temperature and pH on glass dissolution and alteration layer formation
Abstract
Quantifying basaltic glass alteration kinetics is essential for modelling carbon sequestration and global biogeochemical cycles. However, current literature rates diverge by up to two orders of magnitude due to surface area normalization uncertainties (BET vs. geometric) and conflicting reports on the pH-dependence of activation energies (E a ). In this study, we resolve these inconsistencies by combining Vertical Scanning Interferometry (VSI) and in situ synchrotron X-ray Reflectivity (XRR) to decouple glass network dissolution from Amorphous Silicarich Surface Layer (ASSL) growth between 5 and 60 • C and pH 2-5. Our results demonstrate that both dissolution and ASSL growth proceed linearly over time, following a surface-reaction-controlled regime. We show that the surface retreat method (VSI) provides a robust, normalization-independent proxy for network breakdown, yielding rates consistent with Si release. Furthermore, XRR data reveal that steady-state ASSL densities decrease with increasing growth rates, suggesting the formation of more porous structures at low pH. Contrary to common assumptions in long-term field rates, we find no evidence of surface passivation: ASSLs remain permeable and do not act as diffusion barriers over weeks-long experiments, accounting for up to 80% of the total altered volume. The temperature dependence of the dissolution rate (r) is best described by a pH-dependent Arrhenius law: H+ where A pH is the pH-dependent preexponential factor, R is the gas constant, a H+ is the activity of protons, n the reaction order with respect to protons, which is close to 1 on the investigated temperature range, and where the apparent E a decreases from 62.9 ± 2.0 kJ/mol at pH 2 to values near zero (< 20 kJ/mol) as the pH approaches the point of zero charge of the glass. By providing quantitatively decoupled kinetics for substrate dissolution and layer formation, this work offers a high-resolution framework to refine predictive models of basalt weathering in both natural and engineered acidic environments.
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BibTeX
@article{pusztai2026alteration,
title = {{Alteration kinetics of basaltic glass in acidic conditions: The effect of temperature and pH on glass dissolution and alteration layer formation}},
author = {Arpad Pusztai and Bastien Wild and Samuel Tardif and Zijie Liu and François Guyot and Imene Esteve and Alejandro Fernandez-Martinez and Damien Daval},
journal = {Chemical Geology},
year = {2026},
month = jun,
doi = {10.1016/j.chemgeo.2026.123577},
url = {https://hal.science/hal-05763273v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Alteration kinetics of basaltic glass in acidic conditions: The effect of temperature and pH on glass dissolution and alteration layer formation
AU - Arpad Pusztai
AU - Bastien Wild
AU - Samuel Tardif
AU - Zijie Liu
AU - François Guyot
AU - Imene Esteve
AU - Alejandro Fernandez-Martinez
AU - Damien Daval
PY - 2026
DA - 2026/06/26
JO - Chemical Geology
DO - 10.1016/j.chemgeo.2026.123577
UR - https://hal.science/hal-05763273v1
AB - Quantifying basaltic glass alteration kinetics is essential for modelling carbon sequestration and global biogeochemical cycles. However, current literature rates diverge by up to two orders of magnitude due to surface area normalization uncertainties (BET vs. geometric) and conflicting reports on the pH-dependence of activation energies (E a ). In this study, we resolve these inconsistencies by combining Vertical Scanning Interferometry (VSI) and in situ synchrotron X-ray Reflectivity (XRR) to decouple glass network dissolution from Amorphous Silicarich Surface Layer (ASSL) growth between 5 and 60 • C and pH 2-5. Our results demonstrate that both dissolution and ASSL growth proceed linearly over time, following a surface-reaction-controlled regime. We show that the surface retreat method (VSI) provides a robust, normalization-independent proxy for network breakdown, yielding rates consistent with Si release. Furthermore, XRR data reveal that steady-state ASSL densities decrease with increasing growth rates, suggesting the formation of more porous structures at low pH. Contrary to common assumptions in long-term field rates, we find no evidence of surface passivation: ASSLs remain permeable and do not act as diffusion barriers over weeks-long experiments, accounting for up to 80% of the total altered volume. The temperature dependence of the dissolution rate (r) is best described by a pH-dependent Arrhenius law: H+ where A pH is the pH-dependent preexponential factor, R is the gas constant, a H+ is the activity of protons, n the reaction order with respect to protons, which is close to 1 on the investigated temperature range, and where the apparent E a decreases from 62.9 ± 2.0 kJ/mol at pH 2 to values near zero (< 20 kJ/mol) as the pH approaches the point of zero charge of the glass. By providing quantitatively decoupled kinetics for substrate dissolution and layer formation, this work offers a high-resolution framework to refine predictive models of basalt weathering in both natural and engineered acidic environments.
SN - 0009-2541
ER -