Chemical modification of metal oxide surfaces in supercritical CO2 : The interaction of supercritical CO2 with the adsorbed water layer and the surface hydroxyl groups of a silica surface
Chemical modification of metal oxide surfaces in supercritical CO2 : The interaction of supercritical CO2 with the adsorbed water layer and the surface hydroxyl groups of a silica surface
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DOI：
10.1021/la9805701
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发表时间：
1998-12
期刊：
影响因子：
3.9
通讯作者：
C. Tripp;J. Combes
中科院分区：
文献类型：
--
作者：
C. Tripp;J. Combes
红外光谱法用于探测超临界流体（SCF）条件下CO2与气相二氧化硅的相互作用。通过使用氘代二氧化硅或通过在获得光谱之前排出CO2来克服与羟基光谱区域中的红外光的CO2吸收相关联的实验困难。结果表明，CO2的行为与传统的非水溶剂（即，四氯化碳、甲苯和环己烷）与表面上的水吸附层的相互作用。干燥的二氧化硅容易提取和吸附存在于这些非水溶剂中的残留水，而相反，干燥的二氧化硅在与超临界流体CO2接触时保持干燥。此外，CO2从湿二氧化硅中提取吸附的水。超临界流体溶剂将更多的表面水提取到密度增加的流体相中，并且使用超临界流体CO2的重复提取循环导致从表面去除所有水。研究了超临界CO_2气体与土壤的相互作用。
Infrared spectroscopy was used to probe the interaction of CO2 under supercritical fluid (SCF) conditions with a fumed silica. The experimental difficulties associated with CO2 absorption of infrared light in the hydroxyl spectral region are overcome by using deuterated silica or by venting of the CO2 prior to obtaining a spectrum. It is shown that CO2 behaves quite differently from traditional nonaqueous solvents (i.e., carbon tetrachloride, toluene, and cyclohexane) with respect to interactions with the adsorbed layer of water on the surface. A dry silica easily extracts and adsorbs the residual water present in these nonaqueous solvents whereas, in contrast, a dry silica remains dry when placed in contact with the SCF CO2. Moreover, the CO2 extracts the adsorbed water from wet silica. The SCF solvent extracts more surface water into the fluid phase with increasing density, and repeated extraction cycles with SCF CO2 result in the removal of all water from the surface. The interaction of SCF CO2 with th...