J. Mater. Environ. Sci. 7(3) (2016) 685-693 Azad et al. ISSN: 2028-2508 CODEN: JMESCN 685 Rapid Decolorization of Acid Orange II in Aqueous Solution by Waste Iron Oxide Particles Md. Abul Kalam Azad 1 , Md. Hamidur Rahman 1 , Sheikh Jaber Nurani 1, *, Md. Abdul Halim 1, 2 , Md. Adnan Karim 1 , Fahmida Gulshan 1 1 Department of Materials and Metallurgical Engineering, Bangladesh University of Engineering and Technology, Dhaka- 1000, Bangladesh. 2 Department of Materials Science and Engineering, King Abdullah University of Science & Technology, Saudi Arabia. Received 12 Sept 2015, Revised 13 Dec 2015, Accepted 13 Dec 2015 * Corresponding Author. E-mail: sheikh.jaber.nurani@gmail.com ; Tel: (+8801771360183) Abstract Discharges of highly colored dye effluents in natural water constitute a significant burden on the environment. The solar driven photo-Fenton process based on Fe(III)-oxalate complexes, an important advanced oxidation processes (AOP) technology, has been attracting growing attention for the decomposition of organic dyes. Such processes are based on the light enhanced generation of the highly reactive hydroxyl radicals, which oxidize the organic matter in solution and convert it completely into water, CO 2 and inorganic compounds. In the present study, the effectiveness of iron oxide wastes generated in steel re-rolling mills to decompose a synthesized textile dye named Acid Orange II under UV illuminations was investigated. The decomposition of dye by iron oxide suspension at neutral solution pH was investigated. The experiments were carried out by varying amount of Iron Oxide (IO) catalyst (0.05–1 g/100mL) in Oxalic Acid (OA) concentration of 1mmol/100 mL solution and with initial dye concentration of 0.1 mmol/100mL solution. The optimum catalyst dose was found to be 0.05 g/100mL solution. We also studied the effect of pH and initial dye concentration on the degradation behaviour. From this study it was found that iron oxide wastes could be useful in treating dye wastes thus can play an important role to minimize both iron oxide and dye wastes. Keywords: Photocatalytic activity, Photo-ferrioxalate process, Acid Orange II. 1. Introduction Water is an indispensable requirement of life, as well as industries which are working for the betterment of human life and health. Industrialization made a deep impact on human health directly or indirectly creating environment (air , water ,soil ) polluted by releasing wastes and untreated wastewater , into the environment. In many countries, most of the textile industries are using color materials like dyes and pigments, and effluents are released as a textile effluent to canal, river, and sea without further treatments and purifications. In presence of these organic compounds, water becomes unusable for practical uses. Colorants – dyes and pigments – are a growing pollution problem in the industrial and household wastewater as a result of their extensive use and relative stability towards degradation. Dyes undergo chemical changes as well as biological changes in the aquatic system, consume dissolved O2 and thus disturb the aquatic eco-system. The untreated dyes in effluents from textile and coloring are a group of hazardous chemicals as well as major sources of water pollution. It is therefore necessary to treat the water containing color dyes and other organic compounds to discharge them. Due to the complex aromatic structure and stability of these dyes, conventional biological pre-treatment methods are ineffective for degradation. Also low efficiency and low reaction rate are associated with these methods caused the methods to be ineffective. The typical dyestuff treatment includes physical and chemical methods, such as coagulation/flocculation, activated carbon, adsorption and bio-treatment, ozonation, sodium hypochlorite treatment, photochemical decolourization. Amongst the disadvantages of these methods are either formation of large amounts of sludge, or generation of toxic byproducts (aromatic amines) when the