ZIF-67-based Composite Membranes Generated from Carboxymethyl Chitosan and Nylon Mesh for Separation Applications

Nylon mesh has been applied in various fields because of its intrinsic mechanical and chemical stability. However, its application is limited by its surface property. In this work, nylon mesh was first designed to integrate with a zeolitic imidazolate framework-67 (ZIF-67) with a distinct hydrophobic property. Herein, the mechanically stable nylon mesh/carboxymethyl chitosan/ZIF-67 (NY/CMCS/ZIF-67) composite membranes were prepared via layer-by-layer self-assembly of CMCS surface functional groups to coordinate with cobalt ion and in situ growth of ZIF-67. The prepared NY/CMCS/ZIF-67 membranes were characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis. After modifications, the ZIF-67 content in the membranes reached 22 %. The water contact angle increased from 47.5 degrees for nylon mesh to 128.8 degrees for NY/CMCS/ZIF-67. The NY/CMCS/ZIF-67 composite membranes exhibited good oil-water emulsion separation property and oil absorption ability. After 15 oil absorption-drying cycle experiments, the oil absorption ability of the membrane was still greater than 95 %, and the oil absorption rate was 6.8 g/g. The modified nylon mesh could still be used for dye removal, the adsorption capacity of the membrane increased by 50 % compared with that of NY/CMCS, and the adsorption processes followed the pseudo-second-order model. Thus, this research provides new insights into the preparation of efficient modified nylon film with great application potential for filtration and separation in complex environments.

Automated summary

Nylon mesh was designed to integrate with ZIF-67 to prepare mechanically stable composite membranes with excellent oil-water separation properties and oil absorption ability. The ZIF-67 content reached 22%, and the water contact angle significantly increased. After 15 oil absorption-drying cycles, the oil absorption ability remained above 95%.