Synergy between heterogeneous catalysis and homogeneous radical reactions for pharmaceutical waste destruction: Perspective

Enormous quantities of pharmaceuticals are consumed by humans leading to a growing and continuous release of harmful components into the environment. Existing conventional water treatment plants are designed mainly for eliminating biodegradable organics and nutrients and cannot degrade pharmaceuticals and personal care products efficiently enough due to their chemical stability. Advanced oxidation processes using radicals generated from ozone can be efficiently combined with heterogeneous catalysis for treatment of wastewater containing pharmaceuticals and personal care products. From the technology viewpoint, elimination of pharmaceuticals from water by heterogeneously catalyzed ozonation should done in a continuous fixed bed reactor. The structured catalysts can be prepared by additive manufacturing using 3D-direct printing of supports/catalysts allowing a high degree of freedom in both the composition and design of the final catalytic material for a fixed bed heterogeneous-homogeneous reaction. Structured materials can exhibit non-periodic structure, such as for example semi-ordered structures, inspired by nature. For periodic and semi-periodic structures, heat and mass transfer should be investigated using computational fluid dynamics and flow imaging methods, guiding further design of novel architectures and subsequently allowing in combination with the materials development efficient control of activity and selectivity. The innovative catalytic reactor engineering should include experimental and numerical investigation of the stage wise injection of the oxidation agent, variation of the reactor cross-section size, changing the distance between the catalyst beds and introduction of the recycle loops.