We can't find the internet
Attempting to reconnect
Something went wrong!
Hang in there while we get back on track
Magnetite–covalent organic framework/polyvinylidene fluoride composite membranes for dual adsorption and visible-light-driven degradation of polystyrene microplastics
Original title: Magnetite–covalent organic framework/polyvinylidene fluoride composite membranes for dual adsorption and visible-light-driven degradation of polystyrene microplastics
Summary
Scientists have created a magnetic, sunlight-powered filter that not only traps tiny plastic particles (polystyrene microplastics) from water but actually breaks them down into harmless components, removing over 95% of them. This matters because microplastics are increasingly found in our water, food, and even our bodies, and this reusable material could offer a practical way to clean them out of water supplies before they reach us. The filter also held up well after ten reuse cycles, suggesting it could be a durable, real-world solution rather than just a lab curiosity.
The widespread accumulation of polystyrene (PS) microplastics in aquatic systems necessitates the development of materials capable of both efficient capture and in situ degradation. Herein, we report magnetically recoverable magnetite (Fe₃O₄)-incorporated covalent organic framework (COF)/polyvinylidene fluoride (PVDF) composite membranes that integrate high-surface-area COFs with Fe₃O₄ nanoparticles within a chemically robust polymer matrix. Three COFs, denoted as AS-COF (bipyridine-based), FA-COF (sulfonated biphenyl-based), and NM-COF (triazine-based), with surface areas of 1280, 1150, and 980 m² g⁻¹, respectively, were employed to systematically tune the electronic structure, interfacial interactions, and photocatalytic performance of the resulting membranes. Structural, spectroscopic, electrochemical, and optical characterization confirmed successful Fe₃O₄ incorporation, preservation of the COF framework, enhanced visible-light absorption, band-gap narrowing, improved charge-transfer behavior, and the formation of interfacial electronic interactions between Fe₃O₄ and the COF framework. Linker-dependent variations in aromaticity, polarity, and electronic structure influenced Fe₃O₄ dispersion, charge-transfer behavior, and photocatalytic activity under visible-light irradiation. The resulting membranes demonstrated rapid adsorption of PS microplastics, achieving adsorption capacities of 400, 315, and 260 mg g⁻¹ for AS-, FA-, and NM-based systems, respectively, with equilibrium attained within 10–20 min and adsorption kinetics well described by a pseudo-second-order model. Among the investigated systems, the AS-based membrane exhibited the highest adsorption and photocatalytic performance, which was attributed to its electron-rich bipyridine framework, enhanced π-conjugation, and stronger interaction with Fe₃O₄ nanoparticles. Under visible-light irradiation, the membranes achieved >95% PS removal efficiency, accompanied by substantial TOC reduction, significant molecular-weight decrease, and FTIR evidence of oxidative polymer degradation, confirming that the observed removal resulted from genuine photocatalytic degradation rather than simple adsorption or membrane filtration. The membranes maintained approximately 80% of their initial activity after ten reuse cycles with negligible iron leaching. This work establishes a multifunctional membrane platform that couples high-capacity adsorption with visible-light-driven photocatalytic degradation, offering a scalable and sustainable approach for the remediation of persistent microplastic pollutants.