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首页> 外文期刊>Langmuir: The ACS Journal of Surfaces and Colloids >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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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

机译：超临界CO2中金属氧化物表面的化学改性：超临界CO2与吸附水层和二氧化硅表面的表面羟基的相互作用

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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 the hydroxyl groups was studied using deuterated silica. Using a dry or wet deuterated silica, the physisorption of CO2 with the isolated SiOD groups is shown to be weak in nature and of the same magnitude as that measured in CCl4. The SiOD band at 2762 cm(-1) is completely shifted to 2710 cm(-1) at relatively low pressures of CO2 (5 bar) and remains shifted with increasing amounts of CO2 up to the highest pressures studied (200 bar). [References: 21]
机译：红外光谱用于探测超临界流体（SCF）条件下二氧化碳与气相二氧化硅的相互作用。通过使用氘化二氧化硅或通过在获得光谱之前排放CO2可以克服与羟​​基光谱区域中的红外光吸收CO2相关的实验难题。结果表明，就与表面上水的吸附层的相互作用而言，CO2的行为与传统的非水溶剂（即四氯化碳，甲苯和环己烷）有很大不同。干燥的二氧化硅很容易提取和吸收这些非水溶剂中残留的水，而相反，干燥的二氧化硅与SCF CO2接触时仍保持干燥。而且，CO 2从湿的二氧化硅中提取吸附的水。 SCF溶剂以增加的密度将更多的地表水提取到液相中，并且使用SCF CO2重复提取循环可从表面除去所有水。使用氘化二氧化硅研究了SCF CO2与羟基的相互作用。使用干的或湿的氘化二氧化硅，表明具有分离的SiOD基团的CO2的物理吸附性质较弱，其大小与CCl4中的测量值相同。在相对较低的CO2压力（5 bar）下，在2762 cm（-1）处的SiOD带已完全移至2710 cm（-1），并且随着CO2量的增加，直至高达所研究的最高压力（200 bar）时，SiOD带仍保持偏移。 [参考：21]

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