硅气凝胶常压制备、表征及对狄氏剂吸附性能研究

Ambient Pressure Synthesis and Characterization of Silica Aerogel as Adsorbent for Dieldrin

以工业水玻璃为硅源,采用三甲基氯硅烷[（CH3）3SiCl,TMCS]/乙醇[CH3CH2OH,EtOH]/正己烷[C6H14]混合液对硅水凝胶进行溶剂交换和表面改性,在常压干燥条件下获得疏水硅气凝胶材料,并对其吸附狄氏剂性能进行了系统评价.BET、FTIR、热重等表征结果显示,制得的硅气凝胶材料接触角在135°--142°之间,比表面积在444--560 m^2.g^-1之间,孔径范围为17.5--23.4nm,孔隙率为94.8%--95.6%,材料在空气中的耐热温度约为380℃.改性剂用量与组成比例对材料性能有较大影响,在TMCS∶EtOH∶C6H14摩尔比为1∶1∶1时,材料疏水性、比表面积和孔容孔径等物理化学性质达到最大值.本方法制备的疏水硅气凝胶对狄氏剂表现出良好的吸附性能,4 h内狄氏剂去除率达到84%;吸附动力学符合准二级动力学模型,吸附速率常数随疏水性增强而增大;Freundlich系数Kf为30.22μg.g^-1,是活性炭的11倍.

Hydrophobic silica aerogels were prepared from cheap waterglass precursors via surface modification of wet gels and ambient pressure drying route. Its adsorption capacity of Dieldrin, a typical of persistent organic pollutants （POPs）, was examined. It is characterized via BET, FTIR, and DSC-TGA. The silica aerogels were highly hydrophobic with contact angles of 135°-142°, and the hydrophobieity of the aerogels could be maintained up to the temperature of 380℃ . The silica aerogels were porous with, pore size distribution of 17.5-23.4 nm, porosity of 94.8 %-95.6 %, and surface area of 444-560 m^2.g^-1 . The results of adsorption experiments indicated that the hydrophobic aerogels could remove 84 % of dieldrin from aqueous solution within 4 h; the adsorption process followed the pseudo-second-order kinetics process. Based on the adsorption equilibrium results, the adsorption capacity of silica aerogel was 11 times bigger than by active carbon.