Metal-organic framework self-cleaning membrane enhanced water purification based on collaborative separation and photocatalysis process

The existence of membrane contamination will not only affect the flux and rejection of the membrane, but also greatly reduce the service life of the membrane. Therefore, the coupling of photocatalytic Metal-organic frameworks (MOFs) with separation membrane to prepare catalytic self-cleaning membrane can effectively alleviate membrane pollution and maintain membrane flux and rejection. The challenge of photocatalytic selfcleaning membrane treatment of organic wastewater is how to ensure a stable catalyst load while maintaining a high membrane flux, rejection and cycle life. In this paper, the heterojunction photocatalyst NH2-MIL- 125@MIL-88B constructed based on the MOF-on-MOF principle was supported on Polyethersulfone (PES) substrate membrane by vacuum filtration method. Then, polyacrylic acid (PAA) and chitosan (CTS) are adhered to the loading side through a co crosslinking reaction, introducing PAA@CTS layer. The PAA@CTS layer not only improves the load stability of the photocatalyst but also enhances the hydrophilicity of the self-cleaning membrane in collaboration with the photocatalyst. The construction of the self-cleaning membrane further increases its flux without affecting the rejection of the base membrane, breaking the tradeoff between permeability and rejection. The rejection of the best self-cleaning membrane was 96.6 %, and the flux was 58.4 L center dot m- 2 center dot h- 1 . In the treatment process of simulated antibiotic wastewater, the flux recovery rate (FRR) of M-2 is as high as 98 %, and the irreversible fouling ratio (Rir) is only 1 %, which proves its good antifouling properties and stability, and is expected to be used for efficient treatment of antibiotic wastewater.