Direct air capture (DAC) and CO2 sequestration with waste brine using a novel sorbent at ambient temperature

Abstract

There is a global consensus that CO₂ capture and sequestration should continue at an accelerated pace to meet the IPCC (Intergovernmental Panel on Climate Change) recommendation in lowering the CO₂ concentration in the atmosphere. In recent years, deployment of direct air capture (DAC) has been on the rise through use of solid sorbents. In this study, we present for the first time a new DAC process that eliminates the need for geological storage and thermal desorption. A hybrid polymeric ion exchanger for decarbonization (DeCarbon-HIX), that is robust and durable, forms the heart of the process. Besides high CO₂ capture capacity from the atmosphere, the DeCarbon-HIX sorbent is amenable to regeneration with waste brine solution (e.g., produced water) containing Ca²⁺ whereby CO₂ is mineralized as solid, innocuous CaCO₃(s). Note that other recently developed DAC processes, namely, moisture swing DAC and electrochemistry-driven processes, operate without thermal energy but require CO₂ storage. This new avenue for DAC offers great opportunities to capture CO₂ in countries and islands where reliable geological storage is non-existent. This carbon dioxide removal methodology can be rapidly scaled up in many regions that are currently inaccessible to DAC.