Lamorena Rheo B, Lee Woojin
Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, 373-1 Guseong-Dong, Yuseong-Gu, Daejon 305-701, Korea.
Environ Sci Technol. 2008 Apr 15;42(8):2753-9. doi: 10.1021/es702179p.
We have identified the effects of solid surface (soil, bentonite, kaolinite, nontronite, and pyrite) and electrolyte (NaCl, KCl, CaCl2, and MgCl2) types on the formation and dissociation of CO2 hydrate in this study. The hydrate formation experiments were conducted by injecting CO2 gas into the soil suspensions with and without electrolytes in a 50 mL pressurized vessel. The formation of CO2 hydrate in deionized water was faster than that in aqueous electrolyte solutions. The addition of soil suspensions accelerated the formation of CO2 hydrate in the electrolyte solutions. The hydrate formation times in the solid suspensions without electrolytes were very similar to that in the deionized water. We did not observe any significant differences between the hydrate dissociation in the solid suspension and that in the deionized water. The pHs of clay mineral suspensions decreased significantly after CO2 hydrate formation and dissociation experiments, while the pH of the soil suspension slightly decreased by less than pH 1 and that of pyrite slightly increased due to the dissolution of CO2 forming carbonic acid. The results obtained from this research could be indirectly applied to the fate of CO2 sequestered into geological formations as well as its storage as a form of CO2 hydrate.
在本研究中，我们确定了固体表面（土壤、膨润土、高岭土、绿脱石和黄铁矿）和电解质（NaCl、KCl、CaCl2和MgCl2）类型对CO2水合物形成和解离的影响。水合物形成实验是通过在一个50 mL的加压容器中，向含有和不含电解质的土壤悬浮液中注入CO2气体来进行的。去离子水中CO2水合物的形成比含水电解质溶液中更快。添加土壤悬浮液加速了含水电解质溶液中CO2水合物的形成。不含电解质的固体悬浮液中的水合物形成时间与去离子水中的非常相似。我们没有观察到固体悬浮液中的水合物解离与去离子水中的水合物解离之间有任何显著差异。在CO2水合物形成和解离实验后，粘土矿物悬浮液的pH值显著下降，而土壤悬浮液的pH值略有下降，降幅小于1个pH单位，黄铁矿悬浮液的pH值因CO2溶解形成碳酸而略有上升。本研究所得结果可间接应用于地质构造中封存的CO2的归宿及其以CO2水合物形式的储存。
