Preparation of methyl vinyl silicone rubber-based separation-photocatalytic composite membrane and its separation and degradation performance of coal chemical volatile organic compounds

The integration of photocatalysis into polymer membranes for volatile organic compounds (VOCs) abatement is often hindered by the poor dispersion and interfacial compatibility of inorganic fillers within the polymer matrix. This study presents a novel dual-function composite membrane by performing surface modification of bismuth oxybromide (BiOBr) to obtain the functional catalyst (BiNSi), followed by incorporating BiNSi into a methyl vinyl silicone rubber (MVQ) matrix. The BiOBr was functionalized with (3-Aminopropyl)triethoxysilane (APTS) and epoxy-modified silicone oil (E-PDMS), which transformed its surface from hydrophilic to highly hydrophobic (water contact angle increased from 66° to 127°). This modification significantly enhanced its compatibility with the MVQ matrix, as confirmed by rheological analysis and molecular dynamics (MD) simulations, which revealed a favorable interaction energy of -599.746 kcal/mol. The optimized membrane, with 0.7 wt% BiNSi loading (M4), exhibited a uniform filler dispersion that created a wrinkled surface morphology, enlarging the specific surface area and increasing the fractional free volume. Consequently, under visible light irradiation (λ ≥ 420 nm), the M4 membrane demonstrated exceptional performance, achieving high removal efficiencies of approximately 90.72% for n-hexane, 97.07% for o-xylene, and 88.23% for an actual coal chemical VOCs mixture with robust long-term stability. Mechanistic investigations revealed that the enhanced photocatalytic activity stems from efficient charge separation, synergistically driven by hydroxyl radicals (·OH), superoxide radicals (·O 2 ⁻), and oxygen vacancies (OVs). This work provides a robust strategy of interfacial engineering to overcome filler agglomeration, successfully coupling high-efficiency VOCs separation with in-situ photocatalytic degradation in a single membrane system. • Interfacial engineering enhances BiNSi filler compatibility with the MVQ matrix. • Composite membrane couples high VOCs separation with photocatalytic activity. • VOCs are degraded in-situ on catalyst surfaces within the membrane. • Photocatalytic mechanism is dominated by ·OH, ·O₂⁻ and OVs synergy.