Dynamics and isotherms of water vapor sorption on mesoporous silica gels modified by different salts
Dynamics and isotherms of water vapor sorption on mesoporous silica gels modified by different salts
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DOI：
10.1134/s0023158410050186
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发表时间：
2010-10
影响因子：
1.1
通讯作者：
Xin Li;Huiling Li;S. Huo;Zhong Li
中科院分区：
文献类型：
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作者：
Xin Li;Huiling Li;S. Huo;Zhong Li
制备了不同金属盐浸渍的介孔硅胶，并对其进行了研究。用氮气吸附法测定了吸附剂的孔结构和比表面积。然后，在303K和不同相对湿度(RH)下测定了水蒸气的吸附等温线和动力学。通过程序升温脱附实验估算了水在硅胶上脱附的活化能。结果表明，随着离子半径的增大(除钙离子外)，介孔硅胶对水的吸附能力降低，CaCl2和LiCl2特别适合用于介孔硅胶的改性，以提高其在中低相对湿度(RH<；80%)下的吸水率和水蒸气容量。初始硅胶的平均孔径和孔容越大，经吸湿盐改性后的吸水率和吸湿容量的累积率越高。由于Ca~(2+)的极化率高于Li~+，CaCl2改性的介孔硅胶的水脱附活化能远高于LiCl改性的介孔硅胶。
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 (Ed) 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 CaCl2and 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 CaCl2were much higher than that on the silica gel modified by LiCl, because the polarizability of the Ca2+was higher than that of Li+.