Effect of experimental parameters on the carbonate mineralization with CaSO sub(4) times 2H sub(2)O using CO sub(2) microbubbles

Carbonate mineralization fixes CO sub(2) as carbonate minerals such as CaCO sub(3) mitigating anthropogenic CO sub(2) related problems. However, studies on the carbonate mineralization using CaSO sub(4) times 2H sub(2)O have not been made widely, even though it is a good source of Ca super(2+). In this study, the CO sub(2) fixation using CaSO sub(4) times 2H sub(2)O was investigated without swinging pH. In addition, the effect of using microbubbles was evaluated and compared with the conventional CO sub(2) bubbles. We injected CO sub(2) microbubbles into the CaSO sub(4) times 2H sub(2)O suspension in which the NaOH solution added to maintain alkaline pH. The development of the carbonation reaction was considered by quantitative analysis of the solid phases using an X-ray diffraction technique. The phase composition study revealed that the efficiency of the carbonate mineralization changes with the concentration ratio (OH super(-)/Ca super(2+)). The condition for 100% CaCO sub(3) was achieved when the concentration ratio was chosen to be between 2 and 3. We also suggested the transformation pathways of CaSO sub(4) times 2H sub(2)O to CaCO sub(3) in terms of the concentration ratio. We believe that the result in this study would be helpful to find the optimal reaction conditions for the CO sub(2) fixing carbonate mineralization when calcium source was chosen from various materials.