Emerging ozone generation strategies: mechanistic insights and application-driven developments

Ozone finds widespread use in water and wastewater treatment, air purification, food preservation, and medical sanitation since it has a very high oxidative potential and it decays easily to produce oxygen without leaving any long-lasting residues. However, in practice, the use of ozone on a large scale and over long periods is often limited due to such practical considerations as high energy use, the possibility of the formation of unwanted oxidation by-products, problems of operational and occupational safety, and restrictions on regulatory standards. This review will provide a critical evaluation of the technologies of ozone generation and its use, with the aspects of environmental protection and process safety taken into consideration. It initially describes the basic physical and chemical properties of ozone, the most commonly used methods of its measurement, monitoring and safe handling. Then, the key methods of ozone generation, i.e., ultraviolet irradiation, dielectric barrier discharge, and electrochemical processes are analyzed and compared systematically in the light of their working principles, system design, energy efficiency, economic viability throughout the system operation, and regarding their safety issues. An assignment of practical application cases is then conducted in order to show performance constraints to realistic operating environments. Lastly, the review presents significant barriers to large-scale deployment, including scale-up, system integration and safety management, and points to future directions of coming up with ozone technologies that are safer, more energy-efficient, and more sustainable.