Influence of supercritical carbon dioxide (scCO₂) curing on carbonation and strength development of brucite recovered from desalination reject brine

Brucite is a potentially sustainable alternative to reactive magnesium oxide (MgO) cement (RMC) with no calcination requirement. This study investigated the effect of elevated CO₂ curing concentrations on CO₂ sequestration, the formation of carbonate phases, and the compressive strength of compacted pellets of brucite nanopowders synthesized from reject brine. It was revealed that the compressive strength of the compacted brucite pellets with optimum water-to-binder ratio (w/b) enhanced by 45% within 4 h under supercritical CO₂ (scCO₂) conditions compared to the maximum strength observed under 20% CO₂ and 80% relative humidity (RH) at 30 ºC conditions_. The scCO₂ curing enabled the formation of a high-density nesquehonite phase primarily responsible for the strength development of the brucite pellets. In addition, the CO₂ sequestration in the scCO₂-cured brucite pellets reached up to 66% of their maximum storage capacity, indicating their excellent CO₂ absorption capability.