Photocatalytic degradation of BTEX from aqueous solution with CNTs/TiO2 nanocomposites

• Main Authors: Yen-Tung Chen, 陳彥彤
• Other Authors: Chung-sying Lu
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/97585289332477123323

碩士 === 國立中興大學 === 環境工程學系所 === 98 === Carbon nanotube/titanium dioxide(CNT/TiO2) nanocomposites were prepared by the sol-gel method and CNTs were oxidized by NaOCl solution before prepared the nanocomposites. TiO2 nanoparticles were chemically absorbed at CNTs defect sites via an ester-type linkage (esterification) between carboxylic acid groups of the oxidized CNTs surfaces and the hydroxyl groups at the surface of the TiO2 nanoparticles. CNT/TiO2 can enhance the photocatalytic activity of benzene, toluene, ethylbenzene and xylene (BTEX) photodegradation in an aqueous solution since CNTs will increase the specific surface area(reactive sites) and reduce the rate of electron/hole pairs recombination. The conversion and rate constant of BTEX photodegradation for CNT/TiO2 had optimal conditions at 1.0 g/L, 10%CNT contents, and 400oC calcinations temperature, respectively, which were much higher than TiO2 and Degussa P25. The reaction obeys pseudo-first-order kinetics. The removal efficiency for BTEX were less than 19.6% from the background experiment, which including photolysis and dark reaction. This means that major mechanism in the whole photoreaction process was photocatalytic degradation. At the influence of aqueous parameters on the rate constant of BTEX photodegradation increased with solution pH and the H2O2 dosage at low concentration, but appeared no remarkable change with solution ionic strength. A comparative study of the effect of initial BTEX concentration on the reaction rate showed that the rate constant decreased with increased the initial concentration of BTEX under the same conditions. This suggests that CNTs exhibit a synergistic effect and can increase the efficiency of electron transfer from TiO2 to CNTs in enhancing the photocatalytic activity. Thus, this study showed the potential use of CNT/TiO2 nanocomposite in degradation of BTEX from wastewater.