3D-printed N-doped porous carbon aerogels for efficient flow-through degradation and disinfection of wastewater

Peroxymonosulfate (PMS)-based advanced oxidation processes (AOPs) have great potential for water treatment. Herein, a 3D nitrogen-doped porous carbon (3D-NPC) aerogel has been prepared by direct ink writing of a hydrogel containing agarose, urea, sodium chloride and hydroxypropyl methylcellulose, and subsequent freeze-drying and pyrolysis. The obtained 3D-printed aerogel exhibits multiple desirable properties including self-supportability, hierarchical porous structure, and good structural stability, and thus can be used as a monolithic catalytic filter in flow-through experiments. The 3D-NPC catalysts have demonstrated excellent PMS-based performances toward degradation of organic dyes and disinfection of bacterial culture. The degradation efficiency of Rhodamine B by 3D-NPC is as high as 97.2% within 5 min and the high degradation efficiency can be sustained for 5 h. Moreover, 100% inactivation of bacteria by 3D-NPC can also be maintained for at least 5 h, which far exceeds those of traditional catalysts. The key reactive species of the 3D-NPC + PMS system is found to be singlet oxygen in both Rhodamine B degradation and antibacterial disinfection, where the non-radical pathway contributes to the majority of the catalytic activity. Our work has innovatively presented a 3D-printed monolithic catalyst for efficient flow-through degradation and disinfection.