Simultaneous Oxidation of SO2 and NOX via Hydroxyl Radicals Using Ozone-Cavitation-Absorption System

The ozone-wet absorption process has attracted widespread attention as an efficient and low-pollution approach for flue gas simultaneous desulfurization and denitrification. Key issues for ozone-wet absorption process mainly focused on how to enhance the ozonation efficiencies, which were always confined by the relatively low mass transfer because of low solubility and stability of ozone in the liquid phase. Cavitation is an effective way to reduce ozone mass transfer resistance by causing turbulence in bulk solution and microcirculation surrounding cavitation bubbles. Therefore, this study innovatively combines cavitation with the ozone-wet oxidation process and applies it for the rapid and simultaneous oxidation of NO X and SO 2 from flue gases as a desulfurization and denitrification process. The system as developed was examined under different operating conditions such as system pH, sodium dodecylbenzene sulfonate (SDBS) concentration, iron (Fe 2+ ), and manganese (Mn 2+ ) content. All of the investigated parameters influenced NO X removal, and the SO 2 removal rate was always kept high. The NO X and SO 2 removal efficiency of as design process was found to be 89.2% for NO X and 98.7% for SO 2 under optimum experimental conditions (i.e., 0.06 g/L of SDBS, 1.5 mmol/L of Fe 2+ and pH of 12.0). The involvement of reactive ·OH was identified using tert-butanol alcohol for the oxidative removal of SO 2 and NO X . The system can be used for the reduction of flue gas pollutants and environmental cleanup. Graphical Abstract