Design and Efficient Construction of Bilayer Al₂O₃/ZrO₂ Mesoporous Membranes for Effective Treatment of Suspension Systems

To treat industrial suspensions efficiently using cost-effective membrane filtration technology, we report the design and efficient construction of a bilayer Al₂O₃/ZrO₂ membrane on a macroporous substrate with an optimized membrane structure and membrane material. To produce the membrane, an Al₂O₃ layer (pore size of 100 nm) was first deposited on the substrate to prevent layer penetration issues, and the thickness of the membrane was optimized using the Hagen-Poiseuille and Darcy equations to model the membrane resistance. A thickness of 6-10 μm was found to be sufficient to cover the rough ceramic substrate. Then, a ZrO₂ layer (mean pore size of 50 nm) was added to the wet Al₂O₃ layer. On the basis of the individual sintering behaviors of each layer, the Al₂O₃ and ZrO₂ layers were cosintered at an appropriate sintering rate, which significantly reduced the energy consumption and fabrication period. Membranes having a pore size of ∼50 nm achieved a higher permeance (650 L m^-2 h^-1 bar^-1) than those reported in the literature. In the treatment of kaolin suspensions, the membranes showed great potential for reducing the turbidity (by nearly 100%) of the suspensions and showed highly stable permeate flux and good regeneration performance, even at high turbidities. This work provides comprehensive research into the design and construction of cost-effective membrane materials for the industrial suspension separation process.