Biobased biodegradable chelating agents enhance coupled ex situ and in situ carbon dioxide mineralization via peridotite dissolution and wormholing

Mantle peridotite, which is also present in near-surface environments, reacts readily with CO 2 , and is expected to be suitable for CO 2 mineralization. However, the low permeability and porosity of mantle peridotite, in addition to its volume changes during carbonation remain major obstacles to large-scale CO 2 mineralization. Here we propose a coupled ex-situ and in-situ CO 2 mineralization approach employing biobased and biodegradable chelating agents. This involves the injection of an acidic chelating agent to enhance the permeability and porosity, along with divalent metal ion extraction to achieve ex-situ CO 2 mineralization on the surface (stage 1). Subsequently, an alkaline chelating agent is employed for CO 2 capture, injection, and enhanced in-situ mineralization (stage 2). This study experimentally demonstrated a substantial permeability enhancement and Mg-Fe cation extraction by chelating agents, a crucial process of stage 1. The injection of acidic chelating agents leads to the formation of prominent wormholes, resulting in a 21-fold increase in permeability within ~20 minutes, indicating the potential to enhance the injectivity and CO 2 mineralization capacity of peridotite.