Preparation of hydrophilic ZIF-8-NH2/PES mixed matrix membranes based on the co-solvent strategy for dye/salt separation

Doping metal-organic frameworks into the casting solution is a common method for preparing mixed matrix membranes. However, metal-organic frameworks are prone to agglomeration and poor dispersion. This can lead to a decline in membrane performance. To address these issues, this work proposed “co-solvent synthesis and in-situ doping” strategy. In this strategy, N,N-Dimethylformamide, which was also the solvent in the casting solution, was chosen as the synthesis carrier for ZIF-8-NH 2 nanoparticles. The prepared ZIF-8-NH 2 suspension could be directly doped into the casting solution in situ. This process eliminated the drying and pre-dispersion steps. Research showed that with 0.5 wt% ZIF-8-NH 2 , the membrane's hydrophilicity significantly improved, with the water contact angle of 72.5°. The pure water flux reached 229 Lm −2 h −1 . Moreover, the retention rates of Congo Red and NaCl were 97.3 % and 3.5 % respectively, demonstrating excellent dye/salt separation. In particular, the flux recovery rate was maintained at more than 91 %, demonstrating good anti-fouling performance. This work provides a promising technical strategy for the efficient treatment of textile dyeing wastewater and resource recovery.