Rapid thermal treatment of interlayer-free ethyl silicate 40 derived membranes for desalination

Wang, Shengnan, Wang, David K., Motuzas, Julius, Smart, Simon and da Costa, Joao C. Diniz (2016) Rapid thermal treatment of interlayer-free ethyl silicate 40 derived membranes for desalination. Journal of Membrane Science, 516 94-103. doi:10.1016/j.memsci.2016.06.005

Author Wang, Shengnan
Wang, David K.
Motuzas, Julius
Smart, Simon
da Costa, Joao C. Diniz
Title Rapid thermal treatment of interlayer-free ethyl silicate 40 derived membranes for desalination
Journal name Journal of Membrane Science   Check publisher's open access policy
ISSN 1873-3123
Publication date 2016-10-15
Year available 2016
Sub-type Article (original research)
DOI 10.1016/j.memsci.2016.06.005
Open Access Status Not yet assessed
Volume 516
Start page 94
End page 103
Total pages 10
Place of publication Amsterdam, Netherlands
Publisher Elsevier
Collection year 2017
Language eng
Formatted abstract
This work demonstrates for the first time the preparation of interlayer-free silica membranes by the Rapid Thermal Processing (RTP) method at 630 °C using ethyl silicate (ES40) as a silica precursor. RTP resulted in water being retained inside the xerogel pores at higher temperatures, thus favouring condensation reactions and the formation of siloxane bridges. As a result, RTP ES40 xerogels were stronger than their conventional thermal processing (CTP) counterparts and also had higher pore volumes and surface areas. Nevertheless, RTP ES40 xerogels were characterised by a tri-modal pore size distribution. The majority of pores were in the microporous domain with a minor fraction of mesopores. Successful preparation of membranes without a conventional interlayer was dependent on the pH of the sol-gel, as sols with a pH 4 or 6 were able to penetrate into the α-alumina substrate allowing strong adhesion to the support and formed a defect free top layer. The best interlayer-free RTP silica membrane was prepared with a pH 4 sol reaching high water fluxes of 17.8 kg m−2 h−1 at 60 °C and high salt rejection (>99%) for desalination of 3.5 wt% NaCl synthetic seawater. The dilution of the sol with ethanol also played an important role in the membrane stability. Membranes prepared from a sol of pH 4 with EtOH:Si ratio 255:4 were stable for 120 h, but a reduction in this ratio to 200:4 increased the stability to 300 h. This improvement was attributed to thicker films derived from more viscous sols.
Keyword Desalination
Ethyl silicate
Rapid thermal processing
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Chemical Engineering Publications
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