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

Abstract

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.

Keywords

• Brucite
• Desalination reject brine
• Accelerated carbonation with supercritical CO2
• CO2 sequestration
• Strength development