In situ small-angle X-ray scattering study of cluster formation in carbon micropores
In situ small-angle X-ray scattering study of cluster formation in carbon micropores
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DOI：
10.1016/j.colsurfa.2004.04.008
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发表时间：
2004-07
期刊：
影响因子：
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通讯作者：
T. Iiyama;Y. Kobayashi;K. Kaneko;S. Ozeki
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文献类型：
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作者：
T. Iiyama;Y. Kobayashi;K. Kaneko;S. Ozeki
在303 K下，测量了不同相对压力下沥青基活性炭纤维（ACF）表面吸附水和四氯化碳的原位小角X射线散射（SAXS）。我们将Debye-Bueche理论推广到三相混合体系（碳、吸附相和空位），得到了吸附相的平均维数。X射线散射的零角强度I 0和lag直接反映了分子组装体的形状和尺寸。CCl 4分子均匀地填充微孔，另一方面，水分子通过形成约12个分子的团簇状组装体填充微孔，而与孔宽无关。在小孔径体系（w=0.75nm）中，团簇尺寸不随填充分数φ的变化而变化。而在较宽的孔体系（w=1.13nm）中，团簇随φ的增大而增大。吸附和解吸过程中水团簇的大小和形状的差异可能是导致吸附滞后的原因。因此，原位小角X射线散射测量的I 0、Ia和平均空区尺寸LV可以给出微孔中分子组装的直接信息。
The in situ small-angle X-ray scattering (SAXS) of water and CCl4adsorbed on pitch-based activated carbon fibers (ACF) were measured with different relative pressures at 303K. We extended the Debye-Bueche theory to the three-phase mixed system (carbon, adsorbed phase, and vacant space) to obtain the average dimension of adsorbed phase la. The zero-angle intensity of X-ray scattering I0and lagave direct information on the shape and size of molecular assemblies in micropore. CCl4molecules fill uniformly the micropores, on the other hand, water molecules fill the micropores via the formation of cluster-like assemblies comprising about 12 molecules, irrespective of pore width. In the small pore system (w=0.75nm) the cluster size was unchanged with fractional filling φ. On the other hand, in the wider pore system (w=1.13nm), the cluster grew with φ. It seems that the the difference in the size and shape of water clusters in the adsorption and desorption processes should lead to the adsorption hysteresis. Thus, the I0, la, and average dimension of vacant space lvfrom in situ SAXS measurements may give the direct information on molecular assemblies in micropores.