Preparation of ZnO-glass composite hollow fiber and its application in formation of ZIF-8 membrane

The sintering temperature of ZnO ceramic hollow fibers (HFs) is generally up to 1400 degrees C and presents a major challenge to obtain HFs with high permeability and mechanical strength at lower sintering temperature. This work proposed a glass powder-assisted method to reduce the sintering temperature by using their adhesive property. ZnO-glass composite HFs with longer finger-like channels, high permeability (3.12 x 10(-5)-9.1 x 10(-6) mol center dot m(-2)center dot s(-1)center dot Pa-1) and good mechanical strength (42.12-52.75 MPa) were obtained at sintering temperature of 1150 degrees C. More glass powders can generate stronger bonding effect during the ZnO particles, resulting in a decrease in porosity and an increase in the mechanical strength of ZnO-HF. These ZnO-HFs were further applied for inducing ZIF-8 membranes by one-step solvothermal growth. ZnO not only provides the growth and nucleation centers but also acts as transitional bridge to make the ZIF embed into support to improve the bonding force between membrane and support. Therefore, HF-supported-ZIF-8 membrane exhibited both mechanical and thermal robustness by maintaining their gas separation performance during the 30-min sonication treatment and 50-h operation testing at 25-200 degrees C. Furthermore, this membrane provided good reproducibility. This work opens prospects for preparing ceramic HFs at lower sintering temperature and their functional applications as well as the preparation of MOF membranes.