Co-sintering of ZrO2/Al2O3 bi-layer ultrafiltration membranes supported on built-in piezoelectric quartz

A co-sintering route for fabricating ZrO 2 /Al 2 O 3 bi-layer ultrafiltration membranes on quartz supports was proposed. By combining the piezoelectric support and the weak capillary force of transition layer, a thin (∼300 nm), narrowly distributed pore size, and built-in ultrasonic antifouling ultrafiltration membrane was prepared. Considering the mechanical strength of the Al 2 O 3 layer and the interfacial bonding, a co-sintering temperature of 950 °C was selected. Meanwhile, a holding step at 600 °C was introduced to alleviate the thermodynamic mismatch between the two layers caused by the phase transition of the support. The membrane maintained excellent piezoelectric response, along with high flux (366 L·m −2 ·h −1 ·bar −1 ), low roughness (11.6 nm), and small pore size (∼16 nm). The antifouling performance of the piezoelectric ultrafiltration membrane was evaluated through filtration experiments of nano-sized water-in-oil emulsions. The stable permeability of the ultrafiltration membrane was 2.8 times higher than that of the support and further increased by 16.4 % when in situ ultrasound is applied, reaching 0.829 in the stable normalized flux ( J/J 0 ). Additionally, after cleaning, the membrane flux was almost completely restored. The piezoelectric ceramic membranes prepared by this method have great potential for oil-water separation.