Photocatalysis of low-concentration gaseous organic pollutants over electrospun iron-doped titanium dioxide nanofibers Ho-Hwan Chun a , Joon Yeob Lee b , Wan-Kuen Jo b, * a Department of Naval Architecture and Ocean Engineering, Pusan National University, Busan 609-735, Republic of Korea b Department of Environmental Engineering, Kyungpook National University, Daegu 702-701, Republic of Korea article info Article history: Received 8 June 2013 Received in revised form 22 August 2013 Accepted 28 August 2013 Available online 5 September 2013 Keywords: Spectral characteristic Photocatalytic degradation efficiency Fe-to-Ti ratio Polymer support abstract In this study, iron-doped titania (FeeTiO 2 ) nanoparticles were prepared and then coupled to a polymer material as a support to synthesize FeeTiO 2 nanofibers for photocatalytic degradation of gaseous pol- lutants (benzene, toluene, ethyl benzene, and o-xylene (BTEX)) at environmental sub-ppm levels. The characteristics of as-prepared photocatalysts were determined by SEM, XRD, and FTIR analyses. Spectral analysis of the as-prepared photocatalysts revealed that they were closely associated with the charac- teristics of Fe ions for FeeTiO 2 nanofibers. The photocatalytic degradation efficiencies (PDEs) of BTEX determined via FeeTiO 2 nanofibers varied with the ratios of Fe to Ti, suggesting the presence of an optimal Fe-to-Ti ratio. In addition, the PDEs of BTEX determined via two FeeTiO 2 nanofibers with low Fe- to-Ti ratios (0.001 and 0.004) were higher than those obtained from the undoped FeeTiO 2 nanofibers, whereas those of the other two FeeTiO 2 nanofibers with high Fe-to-Ti ratios (0.008 and 0.012) were lower. The average PDEs of BTEX decreased from 34 to 9%, 68 to 28%, 83 to 45%, and 90 to 55%, respectively, as the stream flow rates increased from 1 to 4 L min 1 . These values also decreased with increasing initial concentration (IC). Specifically, at the lowest IC of 0.1 ppm, the average PDEs of BTEX were 33, 68, 83, and 91%, respectively, while they were 5, 8,12, and 23%, respectively, at the highest IC of 2.0 ppm. Similarly, the PDEs of BTEX decreased significantly as the RH increased. Overall, the electrospun FeeTiO 2 nanofibers could be used to effectively decompose low-concentration gaseous organic pollut- ants when operational conditions were optimized. Ó 2013 Elsevier Masson SAS. All rights reserved. 1. Introduction Heterogenous photocatalytic degradation over titania (TiO 2 ) nanoparticles has become a promising technology for treatment of environmental pollutants [1,2]. Photocatalytic processes can convert a range of organic pollutants to harmless CO 2 and H 2 O via photocatalytic oxidation reactions with photo-produced super- oxide ions and hydroxyl radicals [3]. Nevertheless, photocatalytic techniques employing TiO 2 nanoparticles have often been sub- jected to low photocatalytic activity due to both the recombination effect of electron-hole pairs and low adsorption capacity [4]. Several researchers [5e8] have attempted to address this short- coming of TiO 2 nanoparticles by doping various transition metals to TiO 2 nanoparticles. The results of these efforts have revealed that many transition metal-doped TiO 2 nanoparticles can enhance the photocatalytic activity of TiO 2 owing to reduced amounts of electron-hole pair recombination and elevated adsorption capacity relative to pure TiO 2 nanoparticles. Iron (Fe) is an attractive tran- sition metal that can be doped into TiO 2 nanoparticles to enable their effective photocatalytic enhancement for degradation of aqueous pollutants [8e10]. Although some studies [11,12] have shown that excess transition metals incorporated into TiO 2 could act as electron-hole recombination centers or block reaction sites, thereby lowering photocatalytic activity, this drawback can be overcome by controlling the amount of transition metals loaded into TiO 2 [13,14]. Another advantage of this type of transition metal doping is that the price of Fe is much cheaper than that of noble metals such as Pd, Pt, Rh, Ag, and Au. Unlike aqueous applications, applications of Fe-doped TiO 2 (FeeTiO 2 ) to sub-ppm level gaseous pollutant purification are rarely found in literature. Moreover, in gas applications, nanoparticle-type photocatalysts can be blown away with treated air from photocatalytic reactors, necessitating a supporting material that prevents the loss of nanoparticle-type photocatalysts. In the present study FeeTiO 2 nanoparticles were synthesized and then coupled to a polymer material as a support to fabricate * Corresponding author. Tel.: þ82 53 950 6584; fax: þ82 53 950 6579. E-mail address: wkjo@knu.ac.kr (W.-K. Jo). Contents lists available at ScienceDirect Solid State Sciences journal homepage: www.elsevier.com/locate/ssscie 1293-2558/$ e see front matter Ó 2013 Elsevier Masson SAS. All rights reserved. http://dx.doi.org/10.1016/j.solidstatesciences.2013.08.012 Solid State Sciences 25 (2013) 103e109