Visible light responsive photocatalytic applications of transition metal (M = Cu, Ni and Co) doped a-Fe 2 O 3 nanoparticles R. Satheesh a,1 , K. Vignesh b,1 , A. Suganthi c, *, M. Rajarajan d, * a Department of Chemistry, Sethu Institute of Technology, Madurai 626115, Tamil Nadu, India b Department of Chemistry, College of Science, Yeungnam University, Gyeongbuk 712749, Republic of Korea c P.G. & Research Department of Chemistry, Thiagarajar College, Madurai 625009, Tamil Nadu, India d P.G. & Research Department of Chemistry, C.P.A. College, Bodinayakanur 626513, Tamil Nadu, India A R T I C L E I N F O Article history: Received 30 May 2014 Accepted 18 August 2014 Keywords: Photocatalysis a-Fe 2 O 3 Acid Red-27 VSM Visible light A B S T R A C T Transition metal (M = Cu, Ni and Co) doped iron oxide (Fe 2 O 3 ) nanoparticles with crystallite size in the range of 16–26 nm were successfully prepared by simple co-precipitation technique. The optical, structural and magnetic properties were characterized with UV–vis diffuse reflectance spectroscopy (UV–vis DRS), FT-IR, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and vibrational sample magnetometer (VSM) techniques. The surface area was measured by Brunauer–Emmett–Teller (BET) analysis. The photocatalytic activity was evaluated by the degradation of Acid Red-27 (AR-27) dye under visible light irradiation. The photocatalytic activity of Cu–Fe 2 O 3 was obviously affected by the reaction parameters. The photocatalytic activity of Cu–Fe 2 O 3 was found to be higher than that of Fe 2 O 3, Ni–Fe 2 O 3, and Co–Fe 2 O 3. Moreover, the photocatalyst could be reused for four times without remarkable loss of its activity. ã 2014 Elsevier Ltd. All rights reserved. Introduction In recent years, approximately 12–20% of synthetic dyes have been frequently used in textile industries to color cotton, woolen and polyamide fibers. The untreated dyes are often discharged into the environment owing to incomplete use and washing operations. Discharge of those dye effluents into the natural streams is a dramatic source of water pollution, eutrophication and perturba- tion of aquatic life. Most of these dyes are potentially carcinogenic in human, while some others could inhibit light penetration into streams and photosynthetic process is often affected. Therefore, removal of dyes from water has received increasing attention. Many processes have been extensively used to remove the dye molecules from waste water such as incineration, biological treatment, ozonation, adsorption, coagulation, foam floatation, electrochemical oxidation and membrane separation. These conventional techniques of waste water treatment usually suffer from some drawbacks, including complicated procedures, forma- tion of by-products, expensive energy-intensive, limited versatility and less adaptability to a wide range of dye waste waters. For this reasons, the development of an efficient technology to degrade the dye is the need of the hour. In this context, efforts have been devoted to find other effective treatment methods, among which are called advanced oxidation processes (AOPs). Among the AOPs, semiconductor photocatalysis using metal oxides has emerged as a novel destructive technology which leads to the total mineraliza- tion of organic pollutants without generating harmful by-products at relatively lower costs [1]. TiO 2 , WO 3 , ZnO, CdS, CeO 2 , SnO 2 , ZrO 2 , Sm 2 O 3 , Fe 2 O 3 , Bi 2 O 3 , Sb 2 O 3 , Al 2 O 3 , MoO 3 etc., have been employed as conventional photocatalysts owing to their apposite band gap, chemical stability and high photocatalytic activity [2–4]. Among the conventional photocatalysts, iron oxide (a-Fe 2 O 3 ) has been paid intensive attention due to its stability, eco-friendly, high efficiency, non-toxic and inexpensive nature [5,6]. In addition, magnetic iron oxides can be separated and removed from solution by simply applying an external magnetic field. It is the most important advantage of magnetic based iron oxides [7]. a-Fe 2 O 3 has relatively small bandgap (~2.1 eV) that is appropriate for receiving visible light, corresponds well with the solar spectrum and its conduction band edge is more negative than the H 2 O/H 2 redox potential [8]. However, upon excitation by light there is a competition between electron–hole pair recombination and charge carrier trapping and mediates interfacial charge transfer [9]. Hence, something must be done to prevent recombination of the trapped carriers. This can be achieved by depositing or * Corresponding authors. Tel.: +91 4546 280209; fax: +91 4546 280793. E-mail addresses: suganthitcarts@gmail.com (A. Suganthi), rajarajan_1962@yahoo.com (M. Rajarajan). 1 These authors contributed equally to this work. http://dx.doi.org/10.1016/j.jece.2014.08.016 2213-3437/ ã 2014 Elsevier Ltd. All rights reserved. Journal of Environmental Chemical Engineering 2 (2014) 1956–1968 Contents lists available at ScienceDirect Journal of Environmental Chemical Engineering journal homepage: www.elsevier.com/locate/je ce Downloaded from http://www.elearnica.ir