Abstract
A pore-sealing method for preparation of high-permeance alumina microfiltration (MF) membranes free of any intermediate layers is presented. It involves sequential coating of a polyvinyl butyral (PVB) layer and an alumina membrane precursor on the surface of the macroporous alumina support. An alumina MF membrane with no intermediate layers can be obtained on the support after pyrolysis of the PVB interlayer. The interlayer-free membrane prepared by this method has an average pore diameter of 0.26 μm and a water permeance of 1468 ± 81 L m−2 h−1 bar−1 which is prominently higher than that of the ceramic membranes prepared with other techniques. The conspicuous increase of water permeance is speculated mainly due to the filtration resistance decrease of the interlayer-free ceramic membrane.
Highlights
IntroductionBayat et al.[8] reported that a g-Al2O3 multilayer ultra ltration (UF) membrane on an a-alumina (aAl2O3) substrate was successfully fabricated via the sol–gel processing method
Ceramic membranes with all sorts of insoluble metal oxides such as Al2O3, ZrO2, SiO2 and TiO2 have shown interesting separation and processing properties
A porous ceramic membrane is characterized by a multi-layered asymmetric structure which is composed of a thicker (1–5 mm) support layer with relatively large pores (1–15 mm) to provide mechanical integrity for the membrane systems, an intermediate layer to reduce pore size to mesoporous dimensions and a much thinner (10–50 mm) top layer with small (2–500 nm) and selective pores for selective separation.[2,3]
Summary
Bayat et al.[8] reported that a g-Al2O3 multilayer ultra ltration (UF) membrane on an a-alumina (aAl2O3) substrate was successfully fabricated via the sol–gel processing method. Zou et al.[9] designed one-step preparation of high-performance bi-layer aalumina ultra ltration membranes supported on coarse tubular substrates by co-sintering process In this approach, boehmite sol and alumina nanoparticles were mixed in different ratios for the fabrication of MF layer and the UF layer. A method called “precursor lm ring method” is proposed to improve the permeance of ceramic MF membranes by avoiding intermediate layers and dip-coating process, and efficiently control the thickness of the separation layer.[10] a sacri cial interlayer-based technique has been used to produce membranes without any intermediate layers.[7] Some different polymers such as polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP) and polyvinyl butyral (PVB) can be used as sacri cial phases.[11,12,13] The use of these polymer binders can improve the drying of the wet lm and avoid cracks in the membrane precursor. A high-permeance alumina MF membrane with no intermediate layers can be prepared a er pyrolysis of the PVB interlayer
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