A metal-organic framework (MOF) and graphene oxide (GO) based peroxymonosulfate (PMS) activator applied in pollutant removal

Abstract

Fenton-like reactions based on the peroxymonosulfate (PMS) can efficiently degrade pollutants and have attracted widespread attention. Herein, we reported a facile strategy to synthesize a heterogeneous PMS activator (Zn/Co-MOF@rGO-600) derived from a cobalt-zinc bimetallic metal-organic framework (MOF). The Zn/Co-MOF@rGO-600 was applied as the catalyst for the effective tetracycline (TC) removal during the PMS activation process. The introduction of Zn and the presence of graphene oxide (GO) not only enhanced the yield of the single-atom cobalt (Co0) in the catalyst through the bimetallic synergy but also had a positive effect on adjusting the morphology of the catalyst. The charge transfer resistance (Rct) of Zn/Co-MOF@rGO-600 decreased by 3.15 times after GO modification. The reaction rate constant (k) increased by 14.88 times in the reaction system with Zn/Co-MOF@rGO-600 as PMS activator, the corresponding efficiencies of TC removal and mineralization increased to 91.66 % and 45.04 %, respectively. Density functional theory (DFT) calculation suggested that the bonding energy (Ebon) between PMS and the Zn-Co atom was low enough to − 2.76 eV so that the Zn/Co-MOF@rGO-600 could act as an effective PMS activator. The quenching experiment and the radical spin trap test showed the main generated reactive species were SO4•-, O2•- and 1O2. The presence of SO4•- was the main driving factor for the generation of other radicals such as 1O2 and •OH during the PMS activation process. This research proposes a new reference to fabricate an effective catalyst for PMS activation, which was derived from a bimetallic (Zn/Co) MOFs.