Microwave-matter interaction for enhanced carbon capture by mineral carbonation

The formation of stable and insoluble Mg- and Ca-carbonates and/or hydroxy-carbonate hydrates, through water-mediated reaction of Mg(OH)2 (brucite) and Ca(OH)2 (portlandite) with carbon dioxide, is referred to as mineral carbonation (MC). MC is among the most promising potential solutions for long-term carbon capture and storage (CCS), since it is spontaneous under a wide range of conditions. However, kinetic barriers pose severe limitations to the practical exploitation of MC, implying energy requirements to reach sufficiently high reaction rates. Trying to overcome these hindrances, we show here the application of microwave (MW)-assisted processes for the carbonation of brucite, used as a model system for the carbonation occurring in a number of widely diffused minerals, such as serpentine. The mechanism, kinetics, and energy costs of the reaction, together with the chemical characteristics of the products obtained, are inferred by a combined study, carried out by both a MW synthesizer on bulk brucite water slurries and a purposedly developed microscopy platform, working on nano-scale regions of the surface of brucite single crystals.