Assessing Dissolution Rates and Passivating Layer Effects in Olivine Weathering for Enhanced Carbon Mineralization

Olivine is an appealing material for the mineralization of CO2 due to its inherent susceptibility to chemical weathering in aqueous environments. This natural process involves the dissolution and subsequent reprecipitation of olivine, yielding silica and carbonate species as primary products. Olivine dissolution is heavily dependent on pH and temperature; however, it tends to be slow at the conditions necessary for artificially enhanced weathering. One of the key factors contributing to that is the creation of a silica-rich passivation layer. This interfacial layer acts as a barrier, constraining the transfer of mass and inhibiting the reaction at the interface between the electrolyte and the mineral.
The composition of the interface between olivine and aqueous solutions and the processes involved have been assessed using Confocal Raman Microscopy (CRM) and Fluorescence Lifetime Imaging Microscopy (FLIM). During the ex-situ dissolution of olivine in acidic solutions like H2SO4 and HCl, the formation of an alteration layer has been observed and monitored over time. A comprehensive understanding of the evolution of this interphase during dissolution will offer valuable insights into the kinetics of olivine weathering. Such insights may pave the way for more efficient olivine-based technologies aimed at Carbon Capture and Storage (CCS).