Novel NbCo-MOF as an advanced peroxymonosulfate catalyst for organic pollutants removal: Growth, performance and mechanism study

Multivariate metal-organic frameworks (MTV-MOFs) are expected as catalyst to apply to the advanced oxidation processes (AOPs) based on sulfate radical (SO4·-) to treat wastewater containing organic pollutants. Mixing metals de novo method was combined with stringent solvothermal conditions to synthesize macaroon-like NbCo-MOF catalyst. NbCo-MOF catalyst prepared with different atom ratios and growth time presented various morphology, structure, performance, and distinctive MTV-MOFs growth law which were confirmed by SEM, TEM, EDS, XRD, FTIR, raman spectra and UV-vis spectra. Besides, optimum peroxymonosulfate (PMS) catalytic activation conditions were studied. Furthermore, the effects of anions (Cl-, NO3-, HCO3-, and C2O42-) on NbCo-MOF catalytic activation were explored which were proved very limited. Particularly, the Co2+/Co3+ cycle combining with the Nb4+/Nb5+ cycle for PMS activation were verified by XPS. EPR and quenching experiment results indicated exists non-radical pathway (1O2), but radical pathways are dominant (SO4·- O2·-, and ·OH). Moreover, the TC removal rate exhibited no significant reduce after three times run. Furthermore, NbCo-MOF exhibited excellent decomposing ability towards methylene blue, tylosin tartrate, rhodamine B, and tetracycline with the removal rate reaching to 100%, 98.4%, 99.7%, and 99.7% in 30 min respectively and also maintained good performance in actual water environment.