The azo dyes cannot be treated using conventional methods because of their stability in natural environment and resistance to light and chemical agents. In this research Fe3O4 nanoparticles were synthesized and then the removal of acid red 88 (AR88) in catalyzed ozonation process (COP) was investigated. The removal of AR88 in COP was compared with the sole ozonation process (SOP). In SOP, the removal efficiency of AR88 in 30 min ozonation reaches 72%, while the 80ppm of Fe3O4 improves the removal efficiency and completely the removes dye in 20 min. Effect of various factors (e.g. AR88 and catalyst concentration, and solution pH) on the performance of COP was evaluated. By increasing the catalyst concentration to 400ppm, less time was needed to completely degradation the AR88 due to the availability of ozone molecules to Lewis acid sites on the catalyst surface. In addition, in the pH=10, the ozone molecule invaded the molecule AR88 from the indirect pathway (reactive hydroxyl production) and obtained better results than pH=4 and 7 for AR88 removal.
