Recovery and direct carbonation of brucite from desalination reject brine for use as a construction material

This study investigated the direct carbonation of brucite recovered from reject brine of desalination plants and its mechanical property development as part of an assessment for its potential use as a construction material. Brucite nano-powder was synthesized from reject brine through chemical precipitation with calcium oxide (CaO). Formation of brucite with nano-platelet-like structures was observed. Compacted pellets produced with the brucite precipitates and exposed to 20% carbon dioxide (CO₂) attained a 4-fold increase in the compressive strength (~30 MPa) within one day relative to those cured under the ambient condition. Thermogravimetry and morphological analyses of fragments extracted from the carbonated pellets revealed the formation of amorphous hydrated magnesium carbonates, which contributed to the matrix densification and strength gain. The findings confirm that brucite can be synthesized from reject brine with low-cost and energy-effective procedures and has the capability to sequester CO₂, making it a promising and sustainable material for the construction industry.