One-step coating and characterization of α-Al2O3 microfiltration membrane

•One-step coating MF membranes were prepared on macroporous tubular supports.•The membrane fired at 1300 °C for 2 h has a pure water flux of 441 L m−2 h−1 bar−1.•The membrane has a narrow pore size distribution centered at around 0.27 μm.•The largest pore size of membrane is about 0.3 μm.•Hydrogen bondings lead to crosslinking acceleration and giant network formation.

An one-step coating α-Al2O3 microfiltration membrane without any intermediate layers was prepared directly on macroporous alumina tubular support by dip-coating. Coating suspension was obtained by dispersing α-Al2O3 powder (d50=100 nm) in 1.8 wt% boehmite sol followed by addition of PVA in determined weight percentage and 0.8 g PVP. The hydrogen bondings of boehmite and PVA absorbed on the surface of α-Al2O3 particles lead to crosslinking acceleration and giant network formation. This impedes particles in the membrane forming suspension to infiltrate into the macroporous support. The morphology, pore size distribution and permeance of membrane were investigated. The crack-free membrane fired at 1300 °C for 2 h prepared using the suspension with 25 vol% α-Al2O3 and 3.01 wt% PVA has a permeance of 441 L m−2 h−1 bar−1 with the resistance of 9.55×1011 m−1. The membrane has a narrow pore size distribution centered at around 0.27 μm. Its largest pore size is about 0.3 μm.

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