Flow-through filter divided electrolytic cell enables highly efficient water purification via spatiotemporal alteration in electrocatalytic ozonation processes.

Emerging contaminants with contrasting electronic structures respond differently to molecular ozone (O3) and hydroxyl radicals (•OH), yet conventional electro-peroxone systems mainly exploit cathodic O3 activation while leaving the acidic anodic chamber underutilized. Here, a hydrophilic carbon-fiber-membrane-divided, single-pass flow-through GF/EP reactor was developed to convert the anodic chamber into an active O3-preserving oxidation zone and regulate oxidant exposure by reversing the influent direction. In the cathode-to-anode (C-A) configuration, upstream H2O2/HO2--mediated O3 activation increased the apparent •OH exposure to 0.59 × 10-10 M s, achieving 96.0% ibuprofen (electron-deficient contaminant) removal with a kobs of 0.101 min-1, compared with 82.3% and 0.076 min-1 in A-C. Conversely, the upstream acidic anodic region in A-C preserved molecular O3 and promoted selective electrophilic oxidation of electron-rich contaminants, yielding 99% benzotriazole removal with a kobs of 0.103 min-1. Product identification and DFT calculations revealed configuration-dependent pathways and toxicity evolution. Matching influent direction with contaminant reactivity reduced the specific energy consumption for ibuprofen mineralization to 0.16 kWh g-1. The system also maintained over 80% ibuprofen removal and achieved 47% COD removal in secondary effluent. These results establish flow-direction-regulated oxidant sequencing as a simple and energy-efficient strategy for treating chemically diverse contaminants.