2026-04-02 パシフィック・ノースウェスト国立研究所（PNNL）
Microscopy and surface-sensitive spectroscopy techniques reveal how substrate surface affects cobalt mobility and mineralogy on carbonate mineral surfaces.(Image by Nathan Johnson | Pacific Northwest National Laboratory)
＜関連情報＞
- https://www.pnnl.gov/publications/substrate-structure-influences-critical-mineral-availability-shallow-subsurface
- https://www.sciencedirect.com/science/article/abs/pii/S0009254126000987
炭酸塩表面における水酸化コバルトと炭酸コバルトの競合成長に対する温度の影響 Temperature effects on cobalt hydroxide–cobalt carbonate competitive growth on carbonate surfaces
Shawn L. Riechers, Sebastian T. Mergelsberg, Eugene S. Ilton, Nabajit Lahiri, Yingge Du, Odeta Qafoku, Sebastien N. Kerisit
Chemical Geology Available online: 25 February 2026
DOI:https://doi.org/10.1016/j.chemgeo.2026.123329
Abstract
Cobalt (Co), a critical metal essential for various environmental and industrial processes, undergoes speciation and immobilization in natural systems, primarily interacting with existing mineral surfaces. Understanding the underlying mechanisms of Co immobilization on abundant carbonate surfaces under different environmental conditions is critical for predicting Co mobility, availability, and recovery. In this study, we investigated the temperature-dependent competition between CoCO3 and Co(OH)2 formation on calcite (CaCO3) and magnesite (MgCO3) surfaces. Using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS), we analyzed carbonate substrates exposed to CoCl2 solutions at varying concentrations (0–500 μM) and temperatures (22, 50, and 80 °C). Magnesite surfaces promoted CoCO3 formation due to its low lattice mismatch with sphaerocobaltite (CoCO3). However, this slow-growing CoCO3 component was progressively outcompeted by Co(OH)2 formation as the temperature and/or initial Co concentration increased. On calcite surfaces, the poor lattice mismatch between calcite and sphaerocobaltite led to Co(OH)2 outcompeting CoCO3 formation at all three temperatures. These findings provide critical insights into the roles of substrate composition, solution chemistry, and temperature in controlling Co speciation and mobility. They carry important implications for environmental transport, geochemical cycling, and industrial recovery of cobalt in carbonate-rich systems.
