Development of heterogeneous O3/peroxides and O3/light hybrid techniques in water purification

Hybrid O3/peroxides and UV/O3 processes were designed to overcome the selective reaction between O3 and pollutant during water purification, but these techniques were restrained by the low oxidant-to-ROS convey ratio and high sensitivity to water matrixes, especially solution pH. To these end, the heterogeneous O3/peroxides (O3/H2O2 and O3/persulfate) and photocatalytic ozonation processes emerged. With the addition of effective catalysts, the ROS production, pollutant degradation, and oxidant utilization of these processes were significantly increased. Moreover, some catalysts changed the electronic interaction between O3, H2O2 and persulfate, which broadened their environmental adaptability. However, the interfacial interaction mechanism between catalysts and oxidants was still not clear. The influence of organic pollutants on the electronic interaction mechanism between catalysts and oxidants were often ignored. In addition, due to the flaw in experimental design especially for the inappropriate use of radical scavengers, the mechanisms of the above technologies were controversy. This article reviewed the recent development on the heterogeneous peroxone, heterogeneous O3/persulfate and photocatalytic ozonation processes in water purification, including catalysts design and their function mechanism as well as the existing limitations. This study will deepen understanding of the above technologies.