Constructing the purification-permeability balance via polymerization route: a novel confined layered double...

Although catalytic membranes (CMs) offer advantages in the degradation of emerging contaminants, the purification-permeability imbalance still constrains the development of advanced CMs. Herein, this study ingeniously adopts "memory effect" to embed iron (Fe) single atoms into layered double hydroxide for the construction of a confined Fe_SA-in-LDH CM, which is employed for peroxymonosulfate (PMS) activation. In the Fe_SA-in-LDH/M/PMS system, the thermodynamically favored polymerization-dominated oxidative process is innovatively coupled with the nanoconfinement and convection-enhanced mass transfer in CM. The Fe_SA-in-LDH CM exhibits record-high water purification capability (100% BPA removal and 93.4% TOC reduction), fast kinetics (0.11 and 0.053 ms^-1 for BPA removal and corresponding TOC reduction, respectively), and demonstrates outstanding performance with chemical input efficiency of 0.02 mmol mg^-1 and high permeability of 569.4 L m^-2 h^-1 bar^-1, establishing a stable permeability-purification balance. Moreover, mechanistic insights confirm the vital role of non-radical electron-transfer process in initiating polymerization. The Fe_SA-in-LDH CM demonstrates stable water purification across various interfering anions and a wide pH range, along with versatile applicability in real water matrices. This work elicits a prospective approach to completely eliminate contaminants with minimal chemical usage, bridging the critical research gap in the development of advanced CMs.