Adsorption of water vapor and hydrophobicity of ordered mesoporous silica, FSM-16
Adsorption of water vapor and hydrophobicity of ordered mesoporous silica, FSM-16
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DOI：
10.1016/s1387-1811(98)00075-4
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发表时间：
1998-05-01
影响因子：
5.2
通讯作者：
Fukushima, Y
中科院分区：
文献类型：
--
作者：
Inagaki, S;Fukushima, Y
FSM-16的表面疏水性通过在相同样品上对水的重复吸附-解吸等温线测量来评估。还讨论了FSM-16的孔径大小对吸附滞后的影响。尽管煅烧的FSM-16样品显示出疏水性特征，但即使在25 ℃下与水蒸气接触也会降低疏水性。液态水和FSM-16表面之间的接触角，这是从等温线通过使用修正的开尔文方程计算，从42度下降到19度，在第一，第二和第三次测量的等温线。水在FSM-16表面上的不可逆吸附将改变其疏水性质;这由FSM-16与水蒸气接触前后的红外光谱和苯吸附等温线表明。对于孔径为2.7 nm的FSM-16样品观察到的大滞后随着孔径的减小而减小，并且在1.4 nm处消失。尽管对于其他吸附物如氮气、氩气和氧气也观察到类似的滞后消失行为，但是对于水滞后消失的孔径小于对于其他吸附物的孔径。(C)1998 Elsevier Science B. V.保留所有权利。
Surface hydrophobicity of FSM-16 was evaluated by repeated adsorption-desorption isotherm measurements for water on the same sample. The influence of the pore size of FSM-16 on an adsorption hysteresis was also discussed. Although the calcined FSM-16 sample showed hydrophobic features, the hydrophobicity was decreased by contact with water vapor even at 25 degrees C. The contact angle between liquid water and FSM-16 surface, which was calculated from the isotherm by using the corrected Kelvin equation, decreased from 42 to 19 degrees during the first, second and third measurements of the isotherm. An irreversible adsorption of water on the FSM-16 surface would change the hydrophobic property; this is suggested by infrared spectroscopy and benzene adsorption isotherms of FSM-16 before and after contact with water vapor. Large hysteresis observed for the FSM-16 sample with pore diameter of 2.7 nm was decreased with decreasing the pore size and disappeared at 1.4 nm. Although similar behavior of disappearing hysteresis is also observed for the other adsorbates such as nitrogen, argon and oxygen, the pore size at which the hysteresis disappears for water is smaller than that for the other adsorbates. (C) 1998 Elsevier Science B.V. All rights reserved.