Carbon-Based Catalysts in Ozonation of Aqueous Organic Pollutants

This review summarizes recent applications of carbon-based materials as catalysts in the ozonation of wastewater contaminated with persistent organic pollutants. Methods available for production of commonly used inexpensive carbonaceous materials such as biochar and hydrochar are presented. Differences between production methods of active carbon and biochar or hydrochar are discussed. Interestingly, biochar, in a role of rather simple and cheap charcoal, is catalytically active and increases the rate of oxidative degradation of nonbiodegradable aqueous contaminants such as drugs or textile dyestuffs. This review documents that even the addition of biochar to the ozonized wastewater increases the rate of removal of persistent organic pollutants. Cheap bio-based carbonaceous materials such as biochar work as adsorbent of dissolved pollutants and catalysts for ozone-based degradation of organic compounds via the formation of reactive oxygen species (ROS). Low-molecular-weight degradation products produced by ozonation of pharmaceuticals and textile dyes are presented. The combination of air-based ozone generation, together with application of biochar, represents a sustainable AOP-based wastewater treatment method.