Hajar Salehi - Environmental Science and Technology Research Center, Department of Environmental Health Engineering, Schoolof Public Health, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
Mohammad Hassan Ehrampoush - Environmental Science and Technology Research Center, Department of Environmental Health Engineering, Schoolof Public Health, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
Mohammad Hossein Salmani - Environmental Science and Technology Research Center, Department of Environmental Health Engineering, School of Public Health, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
Hossein Fallahzadeh - Research Center of Prevention and Epidemiology of Non-Communicable Disease, Shahid Sadoughi University of Medical Sciences, Yazd, Iran

Introduction: The use of arsenic contaminated water can cause a variety of adverse health effects in humans. Therefore, it is essential to seek out a method to remove arsenic more efficiently. This study examined the amount of arsenic oxidation by response surface methodology (RSM) based on Box-Bencken design.Materials and Methods: In this study, oxidizing arsenite to arsenate was performed by activation of persulfate with UV and the optimal conditions determined using the RSM based on Box-Bencken design to evaluate the effects of independent variables on the response (arsenite oxidation efficiency) performance and to predict the best response rate. In this study, the effects of different parameters such as pH (3-11), concentration of persulfate (4-14 mM), and initial concentration of arsenic (0.1-0.9 mg/l) on process efficiency were investigated. The number of tests in this study was 45, and the oxidation rate was measured using the UV visible spectrophotometer (DR 6000) and the molybdate colorimetric method.Results: Increasing the concentration of arsenic increased oxidation. However,with increasing pH, the oxidation rate decreased and the highest oxidation rate atall concentrations was observed at pH 3. The value higher than R2 (0.934)indicated that the oxidation of arsenic (v) could be determined by this model.Conclusion: Arsenite is a highly toxic metal that is difficult to remove byconventional treatment methods, but a pre-treatment phase can convert arseniteinto arsenate and facilitate the removal process. In this study, the use of UVactivatedpersulfate increased the efficiency of arsenic oxidation to 96%.

Persulfate Oxidation, Ultraviolet Radiation, Aqueous Solution, Arsenic.