Background and purpose: Ethyl benzene is a toxic aromatic compound derived from petroleum hydrocarbons which usually enters the environment through leakage of oil industries and activities, wastes and effluents released by pharmaceutical industry, plastics, resins and petrochemicals. This study aimed to examine the feasibility of the use of MgO nanoparticles as catalysts in the ozonation process for ethyl-benzene removal from the aqueous environments under laboratory conditions.

Materials and methods: This experimental study was performed on a laboratory scale in a semi-continuous reactor. We studied the effect of different variables such as pH values (3, 5, 7, 12, and 13), ozonation time (5, 10, 20, 30 and 50 min), the dose of MgO nanoparticles (0.1, 0.2, 0.3, 0.4, and 0.5 g), and initial concentration of ethylbenzene (10, 50, 100, 150 and 200 mg/L) on ethyl benzene degradation under catalytic ozonation process. In order to achieve the optimal experimental conditions, response surface methodology (RSM) model was designed and applied. Also, gas chromatography method was used for measuring the residual amounts of ethyl benzene at the end of process.

Results: The results of data analysis showed that the pH (P= 0.0063) and catalyst dose (P= 0.0004) had the greatest impact on the response variable (percent removal of ethyl benzene). Also, optimum removal condition based on suitable analysis of variance and model was achieved at 50 min reaction time, pH 12, initial concentration lower than 50 mg/L, and 0.5 g/L catalyst dose. Under these conditions, the removal efficiency of 99.99% was achieved.

Conclusion: Catalytic ozonation process in the presence of MgO nanoparticles has a high efficiency in the removal of ethylbenzene from aqueous environments.