Preparation of hollow fiber membranes from mullite particles with aid of sintering additives
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ISSN 2226-4108 CN 10-1154/TQ
Research Article
Preparation of hollow fiber membranes from mullite particles with aid of sintering additives Hua LIUa, Jinyun LIUa, Zhou HONGb, Shengxian WANGa, Xuechao GAOa,*, Xuehong GUa,* a
State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, No. 30 Puzhu Road (S), Nanjing 211816, China b Nanjing Membrane Materials Industrial Technology Research Institute Co., Ltd., No. 1 Yuansi Road, Pukou Economic Development Zone, Nanjing 211808, China Received: May 16, 2020; Revised: August 25, 2020; Accepted: September 4, 2020 © The Author(s) 2020.
Abstract: Porous mullite hollow fiber membranes were prepared with a combined phase-inversion and sintering method, using three sintering additives including yttrium stabilized zirconia (YSZ), small mullite particles (SMP), and titanium oxide (TiO2) to promote the particle sintering. The results indicated that all the three additives could improve the sintering performance of mullite hollow fiber membranes due to the decrease in activation energy of mullite grains. Both YSZ and TiO2 could react with mullite grains to generate composite oxides (e.g., ZrSiO4 and Al2TiO5) during sintering, following a reaction-sintering mechanism. Interestingly, the newly generated ZrSiO4 was instable and further decomposed into monoclinic ZrO2 and SiO2 in the sintering process. The decomposition could avoid excessive embedment of composite oxides among mullite grains which have negative impact on mechanical strength of mullite hollow fibers. Overall, the doping of YSZ provided a better promotion effect on the sintering of mullite hollow fiber membranes, where the microstructural and mechanical properties are insensitive to the doping content and sintering temperatures, so it could be used as the candidate for the large-scale preparation of mullite hollow fibers. Keywords: mullite; sintering additives; hollow fiber; membranes; sintering behavior
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Introduction
Ceramic membranes behave high thermo-chemical resistance and were suitable for the separation in harsh environments, such as high temperature and strong solvents. Ceramic membranes are mainly made from the inorganic materials such as alumina [1], zirconia * Corresponding authors. E-mail: X. Gao, [email protected]; X. Gu, [email protected]
[2], and titania [3], and the commercial products are fabricated as flat sheet and tube. Compared with the large tube used in the membrane fabrication, hollow fiber structured ceramic membranes have attracted great attentions due to their ultra-high area/volume ratios and low transfer resistance, where the membrane system could be significantly reduced for the practical application of separation processes [4,5]. Phase-inversion method is often used to prepare the ceramic hollow fiber membranes [1,6,7], and a higher permeability could be derived due to its asymmetric structure [1].
www.springer.com/journal/40145
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J Adv Ceram 2020, 9(6): 0–0
Mullite (3Al2O3·2SiO2) is one of the aluminosilica
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