UV absorption spectra, iodometric determination and pH variation in ozonated water using ozone generator

Abstract

An UV absorption spectroscopy technique for real time detecting of reactive ozone and nitrogen oxides species in ozonated water was compared with the traditional iodometric method. The UV absorption spectra are important for understanding the composition of ozonated water. A commercially available ozone generator was used to obtain ozonated water by the bubbling method. A volume of 200 ml of distilled water was treated with the gaseous mixture resulted from the ozone generator. The UV absorption spectra were recorded between 200-300 nm and the ozone concentration wasdetermined by the iodometric method. The results showed the presence of some characteristic peaks for nitrogen oxides and ozonespecies in the UV absorption spectra, the values of the absorbance increasing in time. It has been shown that, due to the high nitrogen content in the air passed through the corona discharge, nitrogen oxides are mainly produced and less ozone. This could explain also the strong decrease of the pH values, after one hour of water ozonation. The iodometric analysis method showed the synthesis of some agents with strong oxidative potential, which can be both ozone and nitrogen oxides. The water sample treated for one hour with the ozone generator was analysed again after one week and one month, the results showing that reactive oxidizing species were kept also after this time. The UV absorption spectra, concentration of ozone (g·l-1) determined by the traditional iodometric method and evolution of the pH values were assessed.