Functionalized MIL-53 and its derivatives modified Bi2WO6 as effective piezocatalysts and membranes for adsorption and decomposition of organic pollutants

• MIL-53(Fe) particles are calcined to form porous carbon materials doped with Fe 3 O 4 . • Hydrophilic MIL-53(Al) and C/Fe 3 O 4 formed a multifunctional piezocatalyst with Bi 2 WO 6 . • Porous carbon induces surface adsorption and pore diffusion of C/Fe 3 O 4 /MIL-53(Al)/BWO. • Accelerated electron transfer of C/Fe 3 O 4 improves the piezocatalytic activity. • Magnet modulates the surface exposure of MOFs/Bi 2 WO 6 during PVDF membrane casting. Carbon-based composites with high activity and selectivity have broad prospects in the field of synthesis and catalysis. This work describes the controllable encapsulation of Bi 2 WO 6 (BWO) piezocatalysts with the mixture of derivatives and frameworks obtained by calcining MIL-53 metal-organic frameworks (MOFs). The mesoporous carbon and multi-functional groups of C/Fe 3 O 4 derived from the pyrolysis of MIL-53(Fe) can mediate the magnetic recyclability of catalysts and act as electron transfer units. Due to the high thermal stability, MIL-53(Al) mixed together still retains the frameworks and shows ameliorated hydrophobicity induced by porous carbon, which ensures the continuous generation of active radicals. The MOFs-assembled BWO nanoflowers possess the characteristics of complete adsorption-release and piezocatalytic degradation of organic pollutants, and the piezocatalytic degradation efficiency reaches 3.7 times higher than that of pure BWO nanoflowers. We also proposed a magnetic modulation method to obtain efficient macroporous BWO/MOFs-PVDF membranes. The magnetic composite powders can be highly exposed to the membrane surface to form more active sites for piezocatalytic reaction, which can overcome the problem of catalysts embedding in the membrane. This work not only proposes a novel way of synthesizing carbon composite piezocatalysts, but also provides the possibility to obtain more convenient, recyclable and high-performance piezocatalytic membrane, which is of great significance to explore the extensive application of piezocatalyst in sewage treatment.