Growth of TiO2 nano-wall on activated carbon fibers for enhancing the photocatalytic oxidation of benzene in aqueous phase

摘要

In the present study, TiO2 nano-wall networks (TNWs) were successfully grown on the surface of activated carbon fibers (ACFs) pre-coated with TiO2 nanoparticles (TNPs) via a hydrothermal process. The TNWs with an average length of 0.7-0.9 tim grew on the ACFs (ACF-TNW) surface in a three-dimensional direction to a complex structure with good uniformity and high crystallinity, as confirmed by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The maximum removal capacities of benzene in a combined process of photo-oxidation and sorption affinity were 111.6 and 144.8 mg/g for ACF-TiO2 and ACF-TNW, respectively, at pH 5, under UV light irradiation within 80 min. The highest benzene removal efficiency of 98.7% in the ACF-TNW system (in 100 mL of 50 mg/L), also confirmed by the CO2 emission results, was accompanied by total organic carbon (TOC) and chemical oxygen demand (COD) reductions of 79.5 and 82.3%, respectively. The ACF-TNW nanocomposite also showed a higher photocatalytic oxidation of benzene than that of TNPs due to the minimization of electron-hole recombination resulting from the transfer of photo-induced electrons through the ACFs surface. The ACF-TNW nanocomposite was also easily separated from aqueous solution for regeneration and showed good stability after multiple uses. (C) 2016 Elsevier B.V. All rights reserved.