Improved degradation of the aqueous flutriafol using a nanostructure macroporous PbO₂ as reactive electrochemical membrane

Highlights: •The role of structure of 3DEM-PbO₂ REM on electrochemical removal of FTF in the EFR was studied. •The ·OH utilization rate was significantly improved with large oxidation capacity and enhanced mass transfer by EFR. •3DEM-PbO₂ REM operated in EFR is efficient for the polishing of effluent containing FTF. -- Abstract: In order to develop an electrochemical technology with low-energy consumption for water treatment applications, we fabricated a novel reactive electrochemical membrane (REM) operated in cross-flow filtration mode. The REM with three-dimensional ordered macroporous PbO₂ (3DEM-PbO₂) film was synthesized via templated deposition that was based on a porous Ti substrate. Compared to conventional flat Ti/PbO₂ (F-Ti/PbO₂) electrode, the 3DEM-PbO₂ possessed larger specific surface area (38.89 m² g⁻¹), higher oxygen evolution potential (OEP, 1.9 V), larger Voltammetric charge (238 mC cm⁻²) and smaller electron transfer resistance (1.43 Ω). Furthermore, advection-enhanced mass transfer was obtained when the 3DEM-PbO₂ REM is operated in an electrochemical filtration reactor (EFR), relative to a traditional batch reactor (BR). The electrochemical mineralization experiments with flutriafol (FTF) demonstrated that the 3DEM-PbO₂ REM operated in the EFR was active for FTF and TOC removal at a low current density of 5 mA cm⁻². The oxidation current efficiency of REM operated in a EFR was much higher than that of conventional electrochemical system, and the corresponding energy consumption was lower (0.0505 kWh g⁻¹ FTF, at FTF removal of 75%). The hydroxyl radicals (·OH) production and its utilization rate of the REM was significantly improved, resulting from a combination of the strong catalytic activity of 3DEM-PbO₂ and the enhanced mass transfer by filtration mode. Furthermore, computational fluid dynamics (CFD) method was carried out to help explain the improvement of oxidation performance with 3DEM-PbO₂ REM in a EFR. Eventually, the electrocatalysis experiments of practical wastewater demonstrated the extreme promise of 3DEM-PbO₂ REM for tailwater advanced treatment applications.