Ultrafast degradation of organic pollutants enabled by nanofluidic ZIF-67/GO membranes via efficient nanoconfined peroxymonosulfate activation

Abstract

Peroxymonosulfate (PMS)-based advanced oxidation processes are often suggested as a solution for degrading persistent organic pollutants in water. However, despite significant efforts to increase PMS activator catalytic activity, the low yield and short lifespan of reactive radicals present a challenge to their practical application in wastewater treatment, particularly under alkaline conditions. To address this, we have developed nanofluidic zeolite imidazolate framework-67 (ZIF-67)/graphene oxide (GO) membranes for confined PMS activation to remove bisphenol A (BPA) and other organic pollutants from wastewater. The membrane achieves a 100% degradation efficiency of the pollutants at high water fluxes of up to 875 L m-2 h-1 bar-1, with a superfast reaction rate constant (39000 min-1) over all previously reported membrane-based catalyst systems. Quenching experiments and chemical probes confirm that both hydroxyl radicals (·OH) and sulfate radicals (SO4·-) play dominant roles in the degradation of organic pollutants, as supported by electrochemical characterizations. The hybrid porous structure of the ZIF-67/GO membrane consisting of 2D nanochannels between ZIF-67/GO nanosheets and intrinsic ZIF-67 nanopores could offer adjacent pathways for efficient PMS activation and ultrafast BPA degradation. Our findings provide new insight into designing alkaline PMS activators and pave the way for nanoconfinement catalysis in water purification.