吸附剂的物理结构和表面性质的研究——酸处理对硅胶孔结构和吸附性能的影响

Studies on the Physical Structure and Surface Properties of Adsorbents——Effect of Acid-Treatment on Structure and Adsorption Properties of Silica Gels

测定了样品的孔结构参数和水蒸气吸附性能。试验表明:用pH3.00酸化的自来水洗涤酸性水凝胶可制得典型的细孔硅胶;用3mol/L以上的硫酸溶液浸泡酸性水凝胶可制得平均孔半径约为300的特粗孔硅胶。

Na Silicate and H2SO4 are reacted to produce acidic silicic acid hydro-gel. If the hydrogel is washed with acidifying tap water at pH 3, the product is typical fine-pored silica gel with av. pore radius (r) 7.5-8.2A, specific surface area (S) 637-690m2/g and pore volume (V) 0.26mL/g. After the impregnation of acidic hydrogel with H2SO4 solutions of various concentrations for 24 h (and then dried at once), the specific surface area and apparent density decreased with increasing the concentration of the acid used, but the pore volume, av. pore radius and av. particle diameter increased with increasing the concentration of the acid used. When the concentration is sufficiently high (3-l8mol/L), the pore structure and adsorption properties of the resulting silica gel are similar, all of these products are extremely coarse-pored silica gels (r= 292-30oA, S-98m2/g, V= 1.43-1.47ml/g). On the other hand, if the same hydrogel is impregnated with HC1 solutions of various concentrations, the relationship between pore structure of silica gel and concetration of the acid used is roughly similar to that as mentioned above.In the concentration range of 3-16mol/L, the properties of the resulting silica gel are almost consistent, but they are not typical coarse-pored silica gels (r=53A, S = 270m2/g, V = 0.71-0.72mL/g).