BMA porous microspheres loaded with silane-modified Cu/Ni@MOF-TiO₂ for photocatalytic degradation of methylene blue

Here, we report a controllable strategy for fabricating monodispersed microspheres composed of poly(butyl methacrylate) (BMA) and silane-modified Cu/Ni-embedded metal-organic framework (MOF)-TiO₂ composites (denoted as BMA@Cu/Ni@MOF-TiO₂ microsphere) for efficient photocatalytic degradation. Monodispersed oil-in-water (O/W) emulsion templates are prepared by a microfluidic device, which contain silane-modified Cu/Ni@MOF-TiO2 in oil phase. Utilizing benzildimethyl ketal (BDK) as a photoinitiator, porous microspheres can be obtained through a straightforward photopolymerization process initiated by ultraviolet light. When the concentration of the surfactant polyglycerol polyricinoleate (PGPR 90) is 14% (w/v) and the crosslinker trimethylolpropane trimethacrylate (TMPTMA) is 12% (w/v), the BMA@Cu/Ni@MOF-TiO2 microspheres have good monodispersity, and the average diameter is 180.7 μm and coefficient of variation (CV) is 3.64%. When silane-modified Cu/Ni@MOF-TiO2 loading is 0.4% (w/v), the removal rate to methylene blue (MB) is up to 96.2% in 20 min, which is higher than that of powdered (86.6%). Under the optimal conditions, the removal rate of methylene blue reached 99.3% within 50 minutes. Moreover, after 5 cycles of testing, the degradation efficiency remained above 97.94%,, which strongly demonstrated the reusability of BMA@Cu/Ni@MOF-TiO2 microspheres. The photocatalytic mechanism involves the generation of electron-hole pairs in Cu/Ni@MOF-TiO2 under light irradiation, which react with O2 to produce reactive oxygen species (ROS) to degrad MB. The characterization results of XPS, and FTIR show that the silane-modified Cu/Ni@MOF-TiO2 is successfully loaded into the microspheres. BMA@Cu/Ni@MOF-TiO2 microspheres have a specific surface area of 5.962 m2/g and a specific volume of 2.491 cm3/g, providing sufficient diffusion channels and active sites for MB dyes. Therefore, BMA@Cu/Ni@MOF-TiO2 microspheres have excellent recyclability, high stability and attractive photocatalytic degradation efficiency, and show potential application prospects in the future treatment of dye wastewater.