Sonophotocatalytic degradation of Orange II dye using low cost photocatalyst Marcos May-Lozano a , Víctor Mendoza-Escamilla b , Elizabeth Rojas-García a , Ricardo L  opez-Medina a , Gabriela Rivadeneyra-Romero c , Sergio A. Martinez-Delgadillo a, * a Departamento de Ciencias B asicas, Universidad Aut onoma Metropolitana-Azcapotzalco, Av. San Pablo 180, Col. Reynosa Tamaulipas, M exico, D. F., 02200, Mexico b Depto. Electr onica, Universidad Aut onoma Metropolitana-Azcapotzalco, Av. San Pablo 180, Col. Reynosa Tamaulipas, M exico, D. F., 02200, Mexico c Depto. Ingeniería de Petr oleos, Universidad del Istmo, Ciudad Universitaria S/N, Barrio Santa Cruz, 4a. Secci on, Sto. Domingo, Tehuantepec, Oax., C.P. 70760, Mexico article info Article history: Received 31 October 2016 Received in revised form 8 February 2017 Accepted 8 February 2017 Keywords: Photocatalyst Fe 2 O 3 -TiO 2 Sonophotocatalysis Degradation Dyes Orange II abstract The photocatalytic and sonophotocatalytic degradation of Orange II was investigated using a synthesized catalyst with low cost materials. Iron (III) oxide-titanium (IV) oxide (1% Fe) photocatalyst was synthe- sized by sol-gel method and pure titanium dioxide was used as photocatalytic reference material. Their crystallographic structures were determined by X-ray diffraction. The surface area and pore diameter was studied by BrunauereEmmetteTeller method (N 2 adsorption/desorption). The samples were char- acterized by Scanning Electron Microscopy (SEM) with Energy Dispersive X-Ray Analysis (EDX). SEM images show the formation of particles with spherical geometry. Synergistic effects of ultrasound and photocatalysis were demonstrated. Three different ultrasonic frequencies were tested 250 kHz, 500 kHz and 1000 kHz. The best catalytic activity (higher Orange II degradation efficiency) was obtained at 500 kHz. Test results show that it is possible the total decolourisation of the Orange II dye in aqueous media by the sonophotocatalytic process using visible light, without producing hazardous by-products. The process can be considered as a potential environmentally friendly technique for organic synthetic dyes degradation. © 2017 Elsevier Ltd. All rights reserved. 1. Introduction From food and clothing to cosmetics and drugs, color is a chief aspect of industrialized products (Pereira and Alves, 2012). Such demand has a serious environmental cost, because industrial pro- duction and use of colorants requires large amounts of water that is polluted throughout the process (Kant, 2012). Such industrial ef- fluents have long become a serious environmental issue (Ratana and Padhi, 2012.). Due to their solubility, organic synthetic dyes are among the major contributors to water pollution (Zaharia and Suteu, 2012). About 50% of the world production of dyes is azo dyes (Heng et al., 2014), such as Orange II. Industrial wastewaters containing dyes have a high environmental footprint because they are chemically stable, non-biodegradable and potentially carcinogenic (Zaharia and Suteu, 2012). Dyes-containing effluents also carry other harmful chemicals, which form a poisonous mixture that is not chemically inert (Kant, 2012). Therefore direct discharge is undesirable because such effluents are toxic, carcino- genic or mutagenic (Chong et al., 2010). Even if a treatment process before discharge existed, conventional water treatments are not designed to remove synthetic dyes and their degradation by- products (Chuan et al., 2012). Dyes also affect photosynthesis by decreasing light penetration, reducing the amount of dissolved oxygen by blocking the oxygen interchange at the surface and increasing the biochemical oxygen demand (Kant, 2012). Moreover, due to their chemical stability azo dyes cannot be removed effi- ciently by classical wastewater treatments (Heng et al., 2014). Consequently, there is an urgent need to develop effective water treatments that reduce water pollution and increase recycling and reuse. In order to remove dyes from industrial wastewaters, several advanced oxidation processes (AOPs) have been tried (Chong et al., 2010). Among the various AOPs, ultrasonic assisted treatments have * Corresponding author. E-mail address: samd@correo.azc.uam.mx (S.A. Martinez-Delgadillo). Contents lists available at ScienceDirect Journal of Cleaner Production journal homepage: www.elsevier.com/locate/jclepro http://dx.doi.org/10.1016/j.jclepro.2017.02.061 0959-6526/© 2017 Elsevier Ltd. All rights reserved. Journal of Cleaner Production 148 (2017) 836e844