Integrating adsorption and in-situ catalytic regeneration on N doped carbon aerogel for sustainable continuous-flow water treatment.

Abstract

Peroxymonosulfate (PMS) activation renders a promising way for in-situ regeneration of carbon-based adsorbents towards sustainable water decontamination, but the effects of structure and composition of carbon adsorbent on its adsorption and catalytic regeneration performances remains unclear. Herein, the nitrogen-doped carbon aerogels (NCAs) were prepared to couple adsorption and PMS activation in a continuous fixed-bed reactor for effective bisphenol A (BPA) removal. The nitrogen species and carbon structure of NCAs were varied by changing carbonization temperature (700 °C, 800 °C, 900 °C and 1000 °C) to investigate their correlation with the adsorption and catalytic regeneration abilities of NCAs. Results showed the PMS activation significantly boosted the adsorption capacity of NCAs and extended the breakthrough time of BPA. The optimal NCA-800/PMS system showed 1.8 times higher adsorption capacity and 37.5 times longer breakthrough time that those of NCA-800 alone. Moreover, the NCA-800/PMS system also demonstrated good adaptability across a broad pH range (3.0-12.0) and maintained high performance in real surface water matrices. Experimental and characteristic results collectively confirmed the critical roles of carbon structure and N species of NCA in adsorption and catalytic regeneration: On one hand, the intrinsic carbon defects served as the main adsorption site for BPA; on the other hand, the pyrrolic N and graphitic N promoted PMS adsorption and surface-mediated electron transfer process, while the electron-deficient C atoms adjacent to N species induced PMS oxidation into ¹O₂, which jointly contributed to efficient BPA degradation for in-situ regeneration of NCA.