Study on adsorptive features of 1,2,3-trichlorobenzene in water using MWNTs and MWNTs/TiO2

Key words: 
• multi-walled carbon nanotubes /
• 1,2,3-trichlorobenzene /
• adsorption /
• kinetics /
• thermodynamics

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.