One-step sintering for anti-fouling piezoelectric α-quartz and thin layer of alumina membrane

Lead-free piezoelectric ceramics are attracting significant attention in the construction of separation membranes because they offer a self-cleaning function and have no risk of lead leaching from the materials. In this study, the fabrication of cost-sensitive and self-cleaning ceramic composite membranes via co-sintering of a porous α-quartz green support and an alumina microfiltration layer is reported. The α-quartz green support prepared by aqueous gel-casting has benign wettability and flexural strength, which is beneficial for forming a thinner and homogeneous membrane layer by dip-coating. The effects of the co-sintering temperature and dip-coating parameters on the pore size, permeance, mechanical and chemical stabilities, and piezoelectric properties were further investigated. The optimal membrane had an average pore size of 190 nm by co-sintering at 1200 °C and a strongest ultrasound response of 15 mV at an alternating voltage (AV) of 100 V. Finite element analysis showed that the composite membrane generated a beneficial displacement and acoustic pressure (acpr) for cavitation effect. In-situ mitigation of fouling was demonstrated during 500 ppm oil-in-water (O/W) emulsion filtration, which resulted in a stationary flux (J_stat) of 190 L m⁻² h⁻¹·bar⁻¹, increased by 65.7% at 100 V AV.