Fabrication of Fe-doped cobalt zeolitic imidazolate framework derived from Co(OH)2 for degradation of tetracycline via peroxymonosulfate activation

The exploration of transforming insoluble solid hydroxide as a metal source into metal organic frameworks (MOFs) has attracted much attention in recent years. Herein, Fe-doped cobalt zeolitic imidazolate framework (Co-ZIF-(Fe)x, x meant the different adding amount of Fe3+) were successfully synthesized by using radical cobalt layered double hydroxide (Co(OH)2) as a cobalt ion source. The catalytic performance of samples was evaluated by activating peroxymonosulfate (PMS) to degrade tetracycline hydrochloride (TC) from aqueous solution. Remarkably, the Co-ZIF-(Fe)0.5 demonstrated the highest catalytic activity that the removal efficiency of TC could reach up to 96.71% within 5 min, which was 1.136 times higher than Co-ZIF. The Co-ZIF-(Fe)0.5 have a larger surface area (268.97 m2 g−1) and pore volume (0.25 cm3 g−1), which can be contributed to a large number of accessible active sites. The possible TC degradation pathways were investigated on basis of the intermediates. According to the classical radical-quenching test and electron paramagnetic resonance (EPR) characterization, manifested that the degradation of TC was accomplished by the free radical (SO4 −) and the non-radical (1O2) pathways. Moreover, the Co-ZIF-(Fe)0.5/PMS system exhibited a high activity in a wide pH range (4–10) and less influenced by organic and inorganic ions. The effect of actual water (medical wastewater, river water and tap water) was discussed in detail, and the reusability was also be considered. Therefore, this study provided a reference for the fabricating of MOF-based catalysts for wastewater treatment.