Single-Atom Cobalt-Modified Catalytic Membrane for Pollutant Degradation with High Tolerance of Environmental Interferences

Peroxymonosulfate (PMS)-based catalytic oxidation processes represent promising means of degrading organic contaminants for wastewater treatment. However, these systems typically use dispersions of catalytic particles that require challenging recovery steps, and the radical-based oxidation processes are inefficient due to reactions with background species present in natural waters. Herein, we incorporate single-atom cobalt into a catalytic membrane (Co–C3N4) for the selective production of high-valent cobalt-oxo species (Co(IV)=O). The generation of Co(IV)═O is confirmed by 18O isotopic labeling and scavenger experiments. Furthermore, density functional theory calculations show that Co(IV)═O formation rather than radical formation is thermodynamically favorable in the Co–C3N4/PMS process. The Co–C3N4 membrane activates PMS with a rate constant of kobs = 11.1540 min–1, which is nearly 105 times greater than that for traditional heterogeneous catalytic dispersions (i.e., kobs = 0.1065 min–1). Additionally, the Co(IV)═O-mediated oxidation process degrades contaminants with low ionization potentials at accelerated rates (e.g., kobs = 17.2860 min–1 for guaiacol). The process also demonstrates improved resistance to background ions and humic acid, in comparison with conventional radical-based oxidation processes. Our study presents a facile approach to engineer single-atom catalytic membranes for high-valent metal-oxo-mediated PMS-based catalytic oxidation processes, providing promising opportunities for efficiently removing persistent pollutants while mitigating interference from background species.