Rate of dibutylsulfide decomposition by ozonation and the O3/H2O2 advanced oxidation process

A process of dibutylsulfide (DBS) oxidation using advanced methods of oxidation with ozone and hydrogen peroxide was studied. It was demonstrated that depending on pH value there are two mechanisms of DBS oxidation present: ionic and radical. The ionic mechanism predominates in acidic environment and the radical mechanism predominates in alkaline environment. At high pH ozone stability decreases and hydrogen peroxide has a deciding effect on DBS oxidation rate. At pH 9, and at high concentration of hydrogen peroxide (ranging from 0.1 to 1 mol/L), a clear increase in DBS decomposition rate was observed. That was caused by production of hydroperoxide radicals in reaction of hydrogen peroxide and ozone. In solutions pH value of which is close to 2, the rate of DBS oxidation by ozone alone is slower than in a O-3/H2O2 system, regardless the H2O2 concentration. For higher H2O2 concentrations (ranging from 0.1 to 1 mol/L), regardless the pH value of the solution, oxidation in a O-3/H2O2 system is faster, compared to a situation in which ozone is a sole oxidizer. For H2O2 concentrations below 0.1 mol/L and when pH > 2 DBS oxidation in O-3/H2O2 system is slower compared to the situation in which ozone was the only oxidizer. (C) 2008 Elsevier B.V. All rights reserved.