Enhanced degradation of tetrabromobisphenol A by magnetic Fe3O4@ZIF-67 composites as a heterogeneous Fenton-like catalyst

Magnetic Fe 3 O 4 @ZIF-67 composites were prepared, characterized, and used as heterogeneous catalysts to activate peroxymonosulfate (PMS) for the degradation of tetrabromobisphenol A (TBBPA). It was observed that all the added TBBPA (40 mg L −1 ) was completely degraded in 3 min in the Fe 3 O 4 @ZIF-67 (0.1 g L −1 ) + PMS (0.1 g L −1 ) system with a pseudo second-order degradation rate constant ( k ) of 110.3 L g −1  min −1 , being nearly 10 times that (11.8 L g −1  min −1 ) in the ZIF-67 + PMS system and 2000 times that (0.06 L g −1  min −1 ) in the Fe 3 O 4  + PMS system. The observed synergistic catalysis between Fe 3 O 4 and ZIF-67 in Fe 3 O 4 @ZIF-67 enhanced not only the degradation of TBBPA, but also the TOC removal and the release of Br − during the degradation of TBBPA. Multiple reactive species including OH, SO 4 − and 1 O 2 were responsible for the degradation of TBBPA, but 1 O 2 was the dominant one. The synergistic catalytic mechanism of PMS activation by Fe 3 O 4 @ZIF-67 was proposed, which mainly involved the electron donating ability of Fe 2+ in Fe 3 O 4 for enhancing the Co 3+ /Co 2+ cycle. Moreover, Fe 3 O 4 @ZIF-67 showed good recyclability and could be easily recycled by magnetic separation. This work provides an opportunity to construct highly efficient catalysts with magnetic recycling capability.