多壁碳纳米管吸附水中三氯苯动力学及热力学研究

Kinetic and Thermodynamic Studies on the Adsorption of Trichlorobenzene in Water onto Multiwalled Carbon Nanotubes

采用多壁碳纳米管（MWNTs）对水中三氯苯（TCB）的3种同分异构体进行吸附试验,测定了三氯苯在多壁碳纳米管上的吸附等温线和动力学曲线,并研究了pH值对吸附的影响。结果表明,碳纳米管对三氯苯的吸附仅需150min就能基本达到平衡;其吸附动力学和热力学过程可分别用假二级反应动力学模型和Freundlich吸附等温线模型来描述。其热力学参数表明MWNTs吸附TCB过程为自发吸热反应。当pH值在2～11之间变化时,吸附量基本不变,表明H键对MWNTs吸附TCB过程无显著影响,MWNTs对TCB的强吸附作用可能是MWNTs表面与三氯苯苯环之间的π电子共轭作用与疏水性吸附共同作用的结果。

Multiwalled nanotubes（MWNTs） were used as adsorbents to remove trichlorobenzene（TCB） from water,and the gravimetric method was adopted to calculate the adsorption isotherm and kinetic curves of TCB onto carbon nanotubes.Experiments demonstrated that it took only 150 minutes for MWNTs adsorbing to reach equilibrium.The adsorption kinetics and isotherm could be well described by using a pseudo-second-order model and Freundlich isotherm,respectively.The thermodynamic parameters such as equilibrium constant （K？？standard free energy changes（A G？？standard enthalpy change（A H？？and standard entropy change（A S？？were obtained.It indicated that the TCB adsorption process onto MWNTs was spontaneous and endothermic. The fact that the variation of pH values from 2 to 11 had little effect on the TCB adsorption onto MWNTs suggested that H bond between TCB and MWNTs was almost irrelevant.The strong adsorption of TCB onto MWNTs may result from a coaction of hydrophobic adsorption and？Хlectron conjugation between surface of MWNTs and benzene ring of TCB.