Catalytic degradation of antibiotic by Co nanoparticles encapsulated in nitrogen-doped nanocarbon derived from Co-MOF for promoted peroxymonosulfate activation

Simultaneously rational optimization and design of the structure and composition are extremely significant approaches to further improve the performances of catalysts. Herein, a novel magnetic material (C-Co-TN) of Co nanoparticles encapsulated in nitrogen-doped nanocarbon was successfully fabricated as a peroxymonosulfate (PMS) activation catalyst. The derivative C-Co-TN was obtained from one new MOFs of Co-TN (Co(TTPA)(4-Nba)(H2O)2]·4-Nba·0.5DMF, TTPA = tris(4-(1H-1,2,4-triazol-1-yl)phenyl)amine) as a precursor for the first time, in which the Co ions and N-ligands of Co-TN were respectively transformed to Co nanoparticles and nitrogen-doped carbon layer via a one-step pyrolysis. The C-Co-TN with a large specific surface area (258.40 m2 g−1) displayed excellent PMS activation for tetracycline hydrochloride (TCH) degradation with 93.3% efficiency within 30 min superior to the pure Co-TN, in which the obtained kinetic constant for TCH removal in the C-Co-TN/PMS system was 3 times greater than Co-TN/PMS system. The final degradation rate of TCH was maintained above 94% in a wide pH range of 4–9, and 47% of TOC could be eliminated. The higher TCH removal efficiency was attributed to Co0 nanoparticles, Co-Nx/pyridinic N and graphitic N in C-Co-TN as catalytic active sites. The SO4·−, ·OH, O2·− and 1O2 were coexisted in C-Co-TN/PMS system. The work not only provides a possibility for converting MOFs into magnetic catalyst with excellent catalytic performance for water remediation, but also gives underlying insight in non-free radical pathways of heterogeneous catalysis induced by nitrogen-doped porous carbon.