The textile industries contribute to contaminate the environment, especially water resources, due to its high water consumption [1] and the low fixation degree of raw materials such as starching agents, detergents, dyes and others. Congo red is a benzidine-based dye with two azo groups. It causes serious dangers due to its toxic to many organisms, suspected carcinogen and mutagen [2]. Magnetic nanospheres with core-shell structures have applications in bio and environmental due to their high surface area and easy separation under external magnetic fields. Recently, great attention has been paid to combined methods with ultrasound especially in the pollutants removal due to acoustic cavitation which is the formation and subsequent collapse of microbubbles in a liquid [3, 4]. In this work, Fe₃O₄@TiO₂ magnetic nano particle with a core-shell structure were prepared via two steps. The nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and zeta-potential measurement. It was used as an adsorbent for removing anionic Congo red (CR) dye from aqueous solution by a particular amount of Fe₃O₄@TiO₂ (1.4g/L) in the presence and absence of ultrasound. The effects of different parameters such as contact time, pH and temperature were studied in the removal of the pollutant. The results have shown that the decolorization of CR in the presence of ultrasound and Fe₃O₄@TiO₂ was much higher than the mechanical stirring method. The adsorption was increased by decreasing pH and increasing the temperature. Therefore, by increasing positively charged surface of adsorbent, the adsorption percentage increased. Finally, a complete decolorization was achived within 4 min by using ultrasound while it is 20 min by mechanical stirring method. Therefore, the Fe₃O₄@TiO₂ magnetic nanoparticles can be used as an effective adsorbent for the removal of CR from water and wastewater treatment and then it is easy the separate the sorbent from aqueous solution by external magnetic.

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