摘要:
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·min)，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Freundlich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。
Abstract:
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.
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