Carbon Storage and Sequestration as Mineral Carbonates

Development of a CO2 Sequestration Module by Integrating Mineral Activation and Aqueous Carbonation

“…This is a significant improvement over previous studies that required temperatures >185°C and pressures of ≈13.6 MPa, as well as extensive comminution (<37 µm) [21,32].…”

“…The mineral dissolution reaction is likely to be surface-controlled, and the formation of silica-enriched zones could indicate that the reaction is diffusioncontrolled [16]. Further, the formation of silica rims on the reaction surfaces of the minerals may slow the magnesium dissolution [32].…”

“…Laboratory [32]. NETL reported that no solid precipitate was present on immediately removing the sample from the reactor, but in letting the liquid filtrate stand overnight some precipitate did appear.…”

“…The activity of carbonate and bicarbonate ions is dependent on the dissolution of CO 2 (g) and the pH of solution. Previous researchers have utilized buffers such as sodium bicarbonate, and bases such as potassium or sodium hydroxide, to adjust the pH and therefore control the speciation of carbonic acid [32]. Accordingly, experimentation was carried out with distilled water and various reagents using the Parr reactor, under CO 2 pressures ranging from 0.35 to 3.8 MPa.…”

“…Consequently, the focus centered on the carbonate and bicarbonate ion activity. The use of sodium bicarbonate in the carbonation reaction has been established to buffer the pH of solution and consequently control the speciation of bicarbonate and carbonate ions [32] The pH of solution is a fundamental parameter to producing carbonates and the scale of potential industrial applications for mineral carbonation prohibits the consumption of a base or the use of sodium bicarbonate as a "buffer," since it preferentially reacts with Mg 2+ over CO 2 (g). Referring to Figure 3, the P CO2 /pH trend shows the limitation of forming magnesium carbonates without any additional reagents.…”