Two-dimensional Prussian blue analog-based catalytic membrane for effective decontamination of micropollutants

Abstract

Cost-effective, stable, and highly efficient catalytic technology is the key challenge for wastewater treatment based on advanced oxidation processes. Catalytic membranes, functioning as heterogeneous advanced oxidation microreactors, offer substantial advantages in the removal of organic pollutants. However, creating catalytic membranes with a high density of active sites for efficient and rapid degradation of pollutants in continuously flowing solutions poses challenges for practical applications. In this study, a two-dimensional Co/Fe-PBA catalytic membrane was developed and fixed onto a hydrophilic polytetrafluoroethylene (PTFE) membrane modified with polydopamine (PDA) through vacuum filtration. This membrane was used to activate peracetic acid (PAA) for the degradation of 17α-ethinylestradiol (EE2), an emerging environmental endocrine disruptor. The interaction between PAA and Co/Fe-PBA induces the continuous and rapid generation of free radicals and singlet oxygen (¹O₂). Furthermore, the hydrophilic catalytic membrane, containing nano-confined channels, facilitates the efficient transfer of aqueous solutions. The introduction of a PDA layer acts as an in-situ metal ion chelator, dynamically capturing leached metal ion during catalysis and thereby mitigating efficiency loss while reducing metal ion leaching. The Co/Fe-PBA/PDA catalytic membrane shows excellent efficiency in activating PAA to degrade EE2, with a catalytic efficiency close to 100 % in a single-pass filtration mode. In continuous flow mode, it maintains a 95 % degradation rate after 5 h of continuous filtration. The CH₃C(O)OO• radical and non-radical ¹O₂ are the primary reactive oxygen species (ROS) responsible for the oxidation of EE2. The degradation products of EE2 were identified through LC-MS analysis, and computational predictions indicate that, compared to EE2, the overall ecotoxicity of the degradation products is lower. The catalytic membrane also exhibits high degradation efficiencies for various organic pollutants. The activation of PAA by the catalytic membrane for EE2 degradation demonstrates excellent catalytic performance and mass transfer efficiency, overcoming the challenge of recycling powdery catalysts and providing new insights for the removal of emerging contaminants.