Ultrasonic-assisted fabrication of high flux T-type zeolite membranes on alumina hollow fibers

Ultrasonic-assisted pretreatment prior to hydrothermal synthesis is employed for the first time in the preparation of T-type zeolite membranes on α-Al2O3 hollow fibers by secondary growth. The synthesis time can be shortened from 40h to 24h with only 0.5h ultrasonic pretreatment of the synthesis solution. Elongating ultrasonic treatment time to 1.0h has no further improvement for the formation of dense membrane. Typically, the pure phase T-type zeolite membrane synthesized in 24h with 0.5h ultrasonic pretreatment has a separation factor of > 10,000 and a flux of 12.2kgm−2h−1 for 90.0wt% isopropanol aqueous solution at 75°C. When the porosity of the hollow fiber support is 68%, the flux is as high as 14.3kgm−2h−1, which is the highest flux ever reported. The high flux of the membrane can be mainly ascribed to the special structure and porosity of the α-Al2O3 hollow fiber support. Finally, a mechanism for ultrasonic-assisted membrane preparation is proposed.