Pore-scale investigation of shielding effects on CaCO
- 1State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China; Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering of the Ministry of Education, Wuhan University, Wuhan 430072, China
- 2State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China; Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering of the Ministry of Education, Wuhan University, Wuhan 430072, China; Corresponding authors.
Abstract
The coupled mineral dissolution-precipitation process plays a critical role in natural and engineered systems with fluid-rock interaction including geological CO 2 sequestration and contamination treatment of groundwater. A representative scenario is the reaction between limestone and acidic, sulfate-bearing solutions, where the dissolution of carbonate minerals drives gypsum precipitation. Previous studies have investigated the impact of this coupled process on hydraulic parameters through core-flooding experiments. However, the interplay between calcite dissolution (CaCO 3 ) and secondary precipitation (CaSO 4 ) as well as its influence on the reaction rate of CaCO 3 remains unclear. Here, we combine flow visualization experiments in limestone-based microfluidics with post-experiment SEM-EDS characterization to probe how sulfate concentration affects both precipitation morphology and CaCO 3 dissolution rates under the same pH condition (pH=1). Two distinct dissolution-precipitation coupling regimes have been identified. At low sulfate concentrations, the dissolution-dominated regime causes continuous dissolution of limestone throughout experiments because the porous gypsum layer permits continuous acid infiltration into the rock surfaces. Conversely, high sulfate concentrations induce a precipitation-dominated regime, reducing dissolution rates by an order of magnitude as a dense, thick layer completely shields the reactive surface area. We find a critical sulfate concentration threshold that triggers regime transition, wherein the released calcium concentration equilibrates with the supplied sulfate in solution, facilitating the formation of a dense coating layer. Quantified results indicate that the average dissolution rate decreases linearly with the saturation index by one order of magnitude as sulfate concentration increases from 0 to 0.2 mol/L. These findings provide insights into coupled geochemical processes and offer practical guidance for predicting reaction rates in reactive transport modeling.
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BibTeX
@article{zhang2026porescale,
title = {{Pore-scale investigation of shielding effects on CaCO}},
author = {Yanan Zhang and Ran Hu and Chenxing Zhou and Zhi-Bing Yang and Yifeng Chen},
journal = {Biogeotechnics},
year = {2026},
month = oct,
doi = {10.1016/j.bgtech.2025.100186},
url = {https://doi.org/10.1016/j.bgtech.2025.100186},
note = {CC BY},
}
RIS
TY - JOUR
TI - Pore-scale investigation of shielding effects on CaCO
AU - Yanan Zhang
AU - Ran Hu
AU - Chenxing Zhou
AU - Zhi-Bing Yang
AU - Yifeng Chen
PY - 2026
DA - 2026/10/30
JO - Biogeotechnics
DO - 10.1016/j.bgtech.2025.100186
UR - https://doi.org/10.1016/j.bgtech.2025.100186
AB - The coupled mineral dissolution-precipitation process plays a critical role in natural and engineered systems with fluid-rock interaction including geological CO 2 sequestration and contamination treatment of groundwater. A representative scenario is the reaction between limestone and acidic, sulfate-bearing solutions, where the dissolution of carbonate minerals drives gypsum precipitation. Previous studies have investigated the impact of this coupled process on hydraulic parameters through core-flooding experiments. However, the interplay between calcite dissolution (CaCO 3 ) and secondary precipitation (CaSO 4 ) as well as its influence on the reaction rate of CaCO 3 remains unclear. Here, we combine flow visualization experiments in limestone-based microfluidics with post-experiment SEM-EDS characterization to probe how sulfate concentration affects both precipitation morphology and CaCO 3 dissolution rates under the same pH condition (pH=1). Two distinct dissolution-precipitation coupling regimes have been identified. At low sulfate concentrations, the dissolution-dominated regime causes continuous dissolution of limestone throughout experiments because the porous gypsum layer permits continuous acid infiltration into the rock surfaces. Conversely, high sulfate concentrations induce a precipitation-dominated regime, reducing dissolution rates by an order of magnitude as a dense, thick layer completely shields the reactive surface area. We find a critical sulfate concentration threshold that triggers regime transition, wherein the released calcium concentration equilibrates with the supplied sulfate in solution, facilitating the formation of a dense coating layer. Quantified results indicate that the average dissolution rate decreases linearly with the saturation index by one order of magnitude as sulfate concentration increases from 0 to 0.2 mol/L. These findings provide insights into coupled geochemical processes and offer practical guidance for predicting reaction rates in reactive transport modeling.
SN - 2949-9291
ER -