Piezoceramic membrane equipped with superwetting interface and in-situ ultrasound performance for efficient oil/water emulsion separation

Piezoceramic membranes can generate in-situ ultrasound during filtration to mitigate fouling, but their developments are limited due to the lead-rich membrane material and high energy cost. Here, a high-performance lead-free piezoceramic membrane equipped with superwetting interface is presented. The novel membrane consists of a piezoceramic porous quartz support and a superhydrophilic/underwater superoleophobic nanofiber membrane. SiO₂-Al₂O₃-MgO system was promoted in the quartz-based ceramic to obtain a porous support with mechanical strength of 23 MPa and ultrasound emission of 3.4 mV. Microfiltration membrane (pore size of 210 nm) with rough surface was constructed by the attapulgite nanofiber. The underwater oil contact angle of the membrane is 158° and the sliding angle is no more than 7°. The stationary permeance of the piezoceramic membrane was 217 L·m⁻²·h⁻¹·bar⁻¹ when dealing with soybean oil/water emulsion. Ascribed to the low adhesion between oil droplets and the superwetting membrane, its permeance increased by 25.3 % when an in-situ ultrasound at low intensity was applied, while the rejection remained above 99.7 %. The outstanding performance of this superwetting piezoceramic membrane provided a new strategy to develop high-efficient and low energy consumption membrane.