Preparation of oxygen-vacant TiO 2-x and activated carbon fiber composite using a single-step thermal plasma method for low-concentration elemental mercury removal
Journal
Chemical Engineering Journal
Journal Volume
200-202
Pages
18
Date Issued
2012-08-15
Author(s)
Tsai, Cheng Yen
Abstract
Oxygen-vacant TiO 2 (TiO 2-x ) nanoparticles and TiO 2-x /activated carbon fiber (ACF) composites were developed via a N 2 /Ar/He thermal plasma system. The TiO 2-x nanoparticles and TiO 2-x /ACF composites were characterized with TEM, XRD, UV-Vis, ESEM and N 2 adsorption isotherms. The removal effectiveness of TiO 2-x /ACF for gaseous Hg 0 at ppb concentration level and various conditions was subsequently evaluated. The experimental results indicated that the formed TiO 2-x nanoparticles had a size within 10-40nm and a mixture of anatase and rutile phases. The TiO 2-x formed at 7% N 2 concentration had an evident red-shift in wavelength absorption. The ESEM and N 2 adsorption results suggested that the synthesized TiO 2-x nanoparticles unevenly deposited on the ACF surface causing a decrease in total and micropore surface areas/volumes. Hg breakthrough tests revealed that TiO 2-x /ACF composites had a greater Hg removal under UV or visible-light irradiation than those obtained in the dark condition. The presence of O 2 up to 12% greatly enhanced the Hg removal, implying the positive effects of catalytic oxidation. However, moisture reduced Hg removal performance, especially when visible-light irradiation was applied. These results revealed the competitive adsorption between Hg species and H 2 O and the physisorption nature of Hg species on the light-induced hydrophilic TiO 2-x /ACF surface. © 2012 Elsevier B.V.
Subjects
Carbon fiber | Mercury | Oxygen vacancy | Photocatalyst | Thermal plasma
Publisher
ELSEVIER SCIENCE SA
Type
journal article