以羧化多壁碳纳米管为基体、纳米硅溶胶粒为增强相,通过一步液相共混方法制备多壁碳纳米管/二氧化硅纳米复合材料。利用傅里叶变换红外光谱(FTIR)、电子扫描电镜(SEM)、热重(TGA)、孔结构分析(BET/BJH)对其进行了表征。以水中柴油为研究对象考察了该样品对水中柴油的吸附脱除效果,并与纳米二氧化硅胶粒、原生碳纳米管以及活性炭进行对比。结果表明:硅溶胶粒表面修饰后的多壁碳纳米管的聚团行为得以改善,而且材料具有微孔-介孔双孔道结构。对水中直馏柴油的去除率高达97.79%,并于1 h达到吸附平衡。整个吸附过程遵循准二级动力学模型,吸附体系的表观活化能为11.37 k J·mol?1,吸附等温线与Freundlich模型较为吻合,吸附效果明显强于其他3种吸附剂。
The velocity, phase fraction and fluctuation velocity of dense clusters are obtained by analysis of transient velocity signals from laser Doppler velocimeter The local velocity of dense clusters increased linearly with superficial gas velocity, while the cross sectional average solids fraction influence the velocity of dense clusters insignificantly A Boltzmann function is used to describe the velocity radial distribution of dense clusters The radial distribution of the phase fraction for dense clusters is described by using an exponential function With the increase of cross sectional average solids fraction, the local phase fraction of dense clusters increases and the area controlled by dense clusters is enlarged The turbulence intensity of dense clusters is highest in the center of the bed while decreases towards the
