Advanced Oxidant Process with Fe(II)-Catalyzed Alkaline H2O2 Systems for Highly Efficient Concurrent Scavenging of NO and SO2 in High Gravitational Fields

The simultaneous removal of NO and SO2 has always been challenging in a single reactor. The key to solving this problem is to enhance NO conversion to soluble N species. In this study, a high-gravity (HiGee)-enhanced advanced oxidation process (AOP) using a Fe2+-catalyzed alkaline H2O2 system was proposed to improve NO oxidation for simultaneous NO and SO2 attenuation within a single rotating packed bed (RPB). We found that the mixture solution obtained by momentarily mixing FeSO4 and alkaline H2O2 had excellent capacity for thoroughly removing NO and SO2 in the RPB. O2·– has proven to be the dominant radical responsible for NO conversion, with ONOO– acting as an intermediate. FeSO4 promotes NO removal by providing ̇OH from alkaline H2O2, resulting in higher O2·– yields. Increased NaOH is conducive to NO removal because it promotes O2·– generation from H2O2. A high gravity level in the HiGee process significantly intensified NO and SO2 capture because the rapid renewal of the liquid film provided more opportunities for ̇OH, O2·–, and H2O2 to be exposed on the surface of the liquid film. Exploiting this inherent but novel mechanism provides theoretical guidance for developing HiGee-enhanced AOP technology that can simultaneously remove NO and SO2.