MWNTs及MWNTs/TiO_2对水中1,2,3-三氯苯的吸附特性研究

Study on adsorptive features of 1,2,3-trichlorobenzene in water using MWNTs and MWNTs/TiO_2

采用批量平衡实验,对比研究了多壁碳纳米管（MWNTs）及多壁碳纳米管/二氧化钛复合材料（MWNTs/TiO2）对水中1,2,3-三氯苯的吸附特性。结果表明,在相同条件下,MWNTs及MWNTs/TiO2对1,2,3-三氯苯（1,2,3-TCB）的最大吸附量分别为71.8 mg/g和3.05 mg/g,pH值在2~11之间变化时,两者的吸附均不受pH值变化的影响。2种吸附剂的吸附过程均符合拟二级动力学方程,但MWNTs/TiO2对1,2,3-TCB的吸附速率常数为0.4159 g/（mg.m in）,约为MWNTs的50倍左右,说明MWNTs/TiO2具有更强的吸附驱动力。1,2,3-TCB在2种吸附剂上的吸附过程均可用Freund lich吸附等温线来描述,其热力学参数吉布斯自由能△G0均为负、标准焓变△H0与熵变△S0均为正表明,MWNTs及MWNTs/TiO2吸附1,2,3-TCB过程为自发吸热反应。与MWNTs相比,MWNTs/TiO2具有可光催化再生的优点,能用于被污染水体的原位修复。

Adsorptive characteristics of 1,2,3-TCB in aqueous solutions on both MWNTs and MWNTs/TiO2 were comparatively studied through batch equilibrium tests.The results showed that,under the same tested condition,the maximum adsorption capacity of MWNTs and MWNTs/TiO2 were 71.8 mg/g and 3.05 mg/g,respectively,and none of the adsorption was depended on pH value variation from 2~11.The adsorption of the two tested adsorbents conformed to be pseudo-second-order kinetics,however,the adsorption rate constant of MWNTs/TiO2 towards 1,2,3-TCB was 0.4159 g/（mg·min）,which was around 50 times that of the MWNTs.This results indicated that MWNTs/TiO2 had a stronger adsorptive driving force on 1,2,3-TCB.The Freundlich adsorption isotherm well described both the adsorption process of the two adsorbents towards 1,2,3-TCB.According to the results,the thermodynamic parameters were determined,and it was found that gibbs free energy（△G0） was always negative while standard enthalpy change（△H0） and standard entropy change（△S0） were always positive,which suggested that the adsorption processes of 1,2,3-TCB on both MWNTs and MWNTs/TiO2 were spontaneous and endothermic.Further compared with MWNTs,it was found that MWNTs/TiO2 could be well regenerated by photocatalysis,implying it might be applied to in-situ remediation of the contaminated water.