CO_2 Sequestration through Mineral Carbonation of Iron Oxyhydroxides

摘要

Carbon dioxide sequestration via the use of sulfide reductants and mineral carbonation of the iron oxyhydr-oxide polymorphs lepidocrocite, goethite, and akaganeite with supercritical CO_2 (scCO_2) was investigated using in situ attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diflraction (XRD), and transmission electron microscopy (TEM). The exposure of the different iron oxyhydroxides to aqueous sulfide in contact with scCO_2 at -70-100 ℃ resulted in the partial transformation of the minerals to siderite (FeCO_3) and sulfide phases such as pyrite (FeS_2). The relative yield of siderite to iron sulfide bearing mineral product was a strong function of theinitial sulfide concentration. The order o/mmeial reactivity with regard to the amount of sderite fonnation in the scCO_2/sulfide eirvironment for a specific reaction time was goethite< lepidocrociti