Modification of ceramic membranes for pore structure tailoring: The atomic layer deposition route

The technique of atomic layer deposition (ALD) is applied to the structural modification and pore tailoring of ceramic membranes. Ceramic microfiltration membranes with an average pore size of 50 nm are used as substrates, on which Al2O3 is deposited by ALD with the purpose to tailor their pore size. The thickness of the deposited Al2O3 layer increases with the number of ALD cycles, and it is confirmed by scanning electron microscopy that the pore size of the ceramic membrane decreases with increasing ALD cycles until the pores are completely sealed. It is found that an ultrathin selective layer with a gradient porous structure is formed, whose thickness can be tuned by varying the exposure time of percursors. With the increased ALD cycles, the Al2O3-deposited membranes have a decreasing water flux, and an increasing retention to bovine serum albumin. The membrane subjected to 600 ALD cycles has a reduced pure water flux from 1698 L (m2 h bar)−1 for an undeposited membrane to 118 L (m2 h bar)−1, while its BSA retention increases significantly from 2.9% to 97.1%.

The pore structure of ceramic membranes was precisely tailored by atomic layer deposition of uniform and conformal alumina thin films.Figure optionsDownload high-quality image (398 K)Download as PowerPoint slideHighlights
► Atomic layer deposition was used to tailor pore structure of ceramic membranes.
► The membrane pore size was reduced by forming an Al2O3 layer on initial particles.
► Flux and retention can be continuously tuned by changing deposition parameters.
► MF membranes were tailored to UF or dense membranes with increasing ALD cycles.