Design and Efficient Construction of Bilayer Al<sub>2</sub>O<sub>3</sub>/ZrO<sub>2</sub> Mesoporous Membranes for Effective Treatment of Suspension Systems
Dong Zou, Ziyi Meng, Enrico Drioli, Xiaowei Da, Xianfu Chen, Minghui Qiu, Yiqun Fan
Abstract
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.