Dynamics and isotherms of water vapor sorption on mesoporous silica gels modified by different salts |
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| Authors: | Xin Li Huiling Li Siqi Huo Zhong Li |
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| Institution: | 1.Institute of Biomaterial, College of Science,South China Agricultural University,Guangzhou,China;2.The Guangdong Provincial Laboratory of Green Chemical Technology, School of Chemistry and Chemical Engineering,South China University of Technology,Guangzhou,China |
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| Abstract: | The mesoporous silica gels impregnated with different metal salts were prepared and studied. The pore structure and specific
surface area of adsorbents were evaluated using nitrogen adsorption. Then, the sorption isotherms and dynamics of water vapor
were carried out at 303 K and different relative humidity (RH). The temperature programmed desorption experiments were conducted
to estimate the activation energy (E
d) of water desorption on the silica gels. The results showed that the sorption capacity for water decreased with the increase
of the ionic radius (except the calcium ion) and that CaCl2 and LiCl were particularly suitable for use in modification of the mesoporous silica gel to improve their sorption rates
and capacities for water vapor at the lower and medium RH (RH < 80%). The larger the average pore diameter and pore volume
of the initial silica gels, higher the accrual rates of the water vapor sorption rate and capacity were after modification
with hygroscopic salts. The activation energy of the water desorption on the mesoporous silica gel modified by CaCl2 were much higher than that on the silica gel modified by LiCl, because the polarizability of the Ca2+ was higher than that of Li+. |
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