Many organic pollutants are chemically stable and thus cannot be degraded by classical wastewater treatment techniques. To solve this issue, ozone-based advanced oxidation processes using hydroxyl radicals with strong oxidation ability have been recently developed. Here we review hydroxyl radicals in ozone-based advanced oxidation processes with focus on reaction characteristics, generation, detection, and quantitation of hydroxyl radicals. Hydroxyl radicals are generated using ozone micro/nano-bubbles, peroxymonosulfate-activated ozone, ozone coupled with Fenton oxidation, electro-peroxone, or catalytic ozonation. Hydroxyl radicals are detected by electron paramagnetic resonance and quenching experiments. We also present applications in wastewater treatment and reactor design. Ozone-based advanced oxidation combines direct oxidation by ozone molecules and indirect oxidation by reactive oxygen species; regulating these two pathways remains challenging. The generation of hydroxyl radicals depends on the environmental matrix and on the chemical structure, properties, and ozone reactivity of contaminants. Chain reactions among reactive oxygen species induce contradictions during the analysis of results obtained by electron paramagnetic resonance, quenching techniques, and probe methods.

许多有机污染物化学性质稳定，因此不能通过传统的废水处理技术降解。为了解决这个问题，最近开发了利用具有强氧化能力的羟基自由基的基于臭氧的高级氧化工艺。在这里，我们回顾了基于臭氧的高级氧化过程中的羟基自由基，重点关注羟基自由基的反应特征、产生、检测和定量。使用臭氧微/纳米气泡、过一硫酸盐活化臭氧、臭氧结合芬顿氧化、电过氧酮或催化臭氧化产生羟基自由基。通过电子顺磁共振和猝灭实验检测羟基自由基。我们还展示了在废水处理和反应器设计中的应用。臭氧高级氧化结合了臭氧分子的直接氧化和活性氧的间接氧化；调节这两条途径仍然具有挑战性。羟基自由基的产生取决于环境基质以及污染物的化学结构、性质和臭氧反应性。在对电子顺磁共振、猝灭技术和探针方法获得的结果进行分析时，活性氧之间的链式反应会引起矛盾。