Synthesis and characterization of anionic/nonionic surfactant-interceded iron-doped TiO 2 to enhance sorbent/photo-catalytic properties Ajit Sharma, Byeong-Kyu Lee n Department of Civil and Environmental Engineering, University of Ulsan, Nam-gu, Daehak ro 93, Ulsan 680-749, Republic of Korea article info Article history: Received 21 March 2015 Accepted 26 April 2015 Available online 12 May 2015 Keywords: SDS Triton X-100 As(V) TiO 2 /Fe Photo-catalyst Adsorbent abstract We investigated the synthesis, characterization, and application of surfactant-interceded Fe nanoparticle-doped TiO 2 (TiO 2 /Fe-S1 and TiO 2 /Fe-S2) that were used as adsorbents and photo- catalysts for the removal of As(V) ions from aqueous media. Two types of surfactant (anionic (sodium dodecyl sulfate), S1 and non-ionic (Triton X-100), S2) were used to obtain the separation and mono- dispersion of Fe(III) ions in the reaction solution. The nanocomposites were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), UV–vis, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX) and elemental mapping analysis before and after As(V) removal. The Langmuir capacities (q e , mg/g) of the sodium dodecyl sulfate (SDS) and Triton X-100 interceded nanocomposites (TiO 2 /Fe-S1 and TiO 2 /Fe-S2, respectively) for arsenic removal were determined to be 65.79 and 50.76 mg/g, respectively, in aqueous media with As (V) concentration ranges of 0–10 mg/L at pH 6.5. & 2015 Elsevier Inc. All rights reserved. 1. Introduction Arsenic removal by adsorption and photo-catalytic processes is advantageous because of ease of handling, economy and high removal efficiency at low concentrations [1]. Arsenic removal has been developed extensively using titanium dioxide (TiO 2 ). Arsenic removal with titanium is mainly dependent on the characteristics of the adsorbent and the oxidation state of the arsenic ions. TiO 2 offers higher sorption capacities and oxidization of As(III) to As (V) under UV irradiation, which provides more hydroxyl radicals as reactive oxidizing species. Titanium dioxide shows higher removal of As(V) than As(III) as an adsorbent and does not require light irradiation [2–4]. To enhance the arsenic removal efficiency, some bimetal oxide adsorbents have been prepared by researchers [5–9]. TiO 2 combined with oxides of cerium, lanthanum and zirconium can significantly enhance the arsenic removal efficiency [2,10,11]. Iron-doped TiO 2 has also been reported for arsenic removal. For example, the adsorption capacity for As(V) of Fe- doped TiO 2 was twice as high as the parent TiO 2 under similar environmental conditions [12]. Nanoparticles of zero valent iron, iron oxide and titanium dioxide used as nano-sorbents are efficient and effective compared with their macro-sized counter- parts because of the high proportion of active sites on their surface, resulting in increased reactivity and unique catalytic activity [1,3]. Nanoparticles, such as aluminum, nickel, manganese and iron are generally used as bi-functional materials with TiO 2 [2,13–15]. In this study, we focused on size scheming and homogeneous dispersion of the metal nanoparticles, particularly as dopants, on the TiO 2 nano-texture. One method to obtain the size scheme with homogeneous dispersion of metal nanoparticles is the use of surfactants during the precursor reaction solution. The particles surface chemistry is important for size scheming to obtain well- defined and uniform dispersions of metal nanoparticles in the host matrix. The molecules of surfactant typically react with nanopar- ticles in a disperse medium. The particle surface chemistry is changed with treatment by surfactant molecules, which are commonly made as pseudo-aggregates of particle clusters. The surfaces of nanoparticles are difficult to modify because they are evenly covered by negatively charged particles on composite matrices. Nanoparticle synthesis by the precipitation method with molecules of interceded surfactant is an effective process for obtaining uniform modified particle surfaces in a single step and allows controlling the size and surface chemistry [16–18]. Many studies have reported the use of surfactants, such as sodium dodecyl sulfate (SDS), cetyl trimethylammonium chloride, cetyl trimethylammonium bromide and Triton X-100, in the synthesis of nickel oxide, silver oxide and iron oxide nanoparticles [19–23]. Thus, the incorporation of iron nanoparticles into TiO 2 may offer a relatively inexpensive method that could be effective in Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/jssc Journal of Solid State Chemistry http://dx.doi.org/10.1016/j.jssc.2015.04.042 0022-4596/& 2015 Elsevier Inc. All rights reserved. n Corresponding author. Tel.: þ82 52 259 2864; fax: þ82 52 259 2629. E-mail address: bklee@ulsan.ac.kr (B.-K. Lee). Journal of Solid State Chemistry 229 (2015) 1–9