Mineral carbonation of flue gas desulfurization gypsum to produce solid nano carbonates for building materials and allied characterizations

Abstract

This study evaluates the mineral carbonation of flue gas desulfurization (FGD) gypsum to produce solid nano carbonates for building materials and allied characterizations. Solid nano calcium carbonate is produced within 60 min with the application of NaOH and acetone for improving reaction stability and achieving high concentration calcite (CaCO₃) particles. This study details the optimization of a method for synthesizing nano CaCO₃ from FGD gypsum and CO₂ at ambient temperature and atmospheric pressure. In contrast to previous research, this methodology incorporates acetone as a stabilizing agent to inhibit re-dissolution and facilitate the creation of high purity nano calcite. The impact of the selected process on the characteristics of CaCO₃ particles is assessed using Thermal gravimetric analysis and differential thermal analysis (TGA-DTA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy-energy dispersive spectroscopy (FESEM-EDS) and High resolution transmission electron microscopy (HRTEM) techniques. 1 M NaOH solution sample (C1) has shown the optimum conversion of FGD gypsum into solid nano carbonates with 84.08 % CaCO₃ purity, 87.67 % carbonation rate and 94.01 % carbonation efficiency. The mean particle size of produced nano carbonate is found to be 45.72 nm with rhomboidal and spherical shapes. The selected area electron diffraction (SAED) of solid nano carbonates sample showed a distinct spot pattern, indicating its single crystalline nature. This work proposed an advantageous solution, as it facilitates both CO₂ fixation and the generation of solid nano calcium carbonate particles for application in building materials. Future research should focus on the mineral carbonation utilizing various feedstocks, the advancement of efficient processes and the implementation of mineral carbonation at the pilot scale from the perspectives of waste management and circular economy.