Rapid thermal processing of inorganic membranes

▶ Rapid thermal processing (RTP) greatly reduces thermal treatment time of thin inorganic membranes. ▶ RTP results in finer microstructures and more densification. ▶ RTP does not adversely affect membrane integrity. ▶ RTP of supported γ-alumina membranes resulted in similar or better nanofiltration properties. Rapid thermal processing (RTP) methods can be used to majorly reduce the processing time of thin supported inorganic membrane layers. The methods result in a finer, more homogeneous membrane microstructure and can be used to form membrane layers requiring high-temperature processing on supports with limited thermal stability. The short processing time of RTP reduces fabrication cost price, helps improve process optimization, and also encourages exploration of other multi-layer structures. The work in this paper demonstrates the use of RTP for thin defect-free supported mesoporous γ-alumina membranes that have a thickness of ∼400 nm. Conventionally thermal processed (CTP) and RTP γ-alumina membranes were characterized by ellipsometry, microscopy, aqueous ion rejection and permporometry. CTP and RTP membranes showed an aqueous ion rejection of >95% and >97%, respectively for a solution of 1 mol/m 3 calcium chloride dihydrate with 0.01 mol/m 3 aluminum chloride. According to ellipsometry analysis, the porosity of the RTP and CTP membranes are approximately 43 and 50%, respectively. Permporometry provides RTP and CTP membrane pore size, Ø p of 3.4 + 2 t and 4.3 + 2 t nm, respectively where t ≈ 0.35 nm.