Dissolution of serpentine using recyclable ammonium salts for CO2 mineral carbonation

Low efficiency of mineral dissolution and unrecyclable use of additives are two barriers for the development of CO2 mineral carbonation. A new pH-swing CO2 mineralisation process using recyclable ammonium salts is proposed to overcome these barriers. This paper presents the studies of mineral dissolution with ammonium salts. In this study, dissolution of a serpentine sample was performed using a series of aqueous solutions, which include (NH4)2SO4, NH4Cl, NH4HSO4 and H2SO4. NH4HSO4 is the most efficient in terms of extracting Mg extraction from the serpentine sample. At 100 °C 1.4 M NH4HSO4 extracted 100% of Mg from serpentine in 3 h, as well as 98% of Fe and 17.6% of Si. The rate limiting mechanism of serpentine dissolution with NH4HSO4 is a chemical reaction with product layer diffusion control and the activation energy of this dissolution was 40.9 kJ mol−1.