Portlandite wet-synthesis process from phosphogypsum waste using hydroxide medium: application in both CO₂ capture and brine water salinity reduction

Portlandite (Ca(OH)(2)) preparation from phosphogypsum waste (PGW) was evaluated in numerous works; however, the use of this compound is not applied yet in the brine water salinity reduction. In this work, the purity of Ca(OH)(2) prepared from PGW and soda aqueous solution was tested for different NaOH/PG molar ratios (MR) close to the stochiometric value (1.5 < MR < 3). The obtained Ca(OH)(2) at the optimal conditions was used for both the CO2 capture and brine water (BW) salinity reduction, resulting in high-quality calcium carbonate synthesizing. The XRD results show that a MR higher than the stochiometric value (MR > 2) is most efficient to obtain high-quality portlandite (P-2.5 and P-3). An estimation of the carbon capture efficiency of the prepared portlandite was made. Based on the results of this work, using 4 g of P-2.5 allows to capture 2.4 L of CO2 and treat 0.4 L of BW. Overall, our work confirms the technical viability of the proposed route to synergize CO2 capture, BW and PGW recycling. From an economic and ecological standpoint, our investigated routes were eco-friendly and cost-effective.